Date / Year-Month-Day Approved Revision Document No

BLUETOOTH® DOC 2015-12-15 Adopted v1.0.3 3DSP_Spec

Prepared By E-mail Address N.B.
3DG WG barb-main@bluetooth.org

BLUETOOTH 3D SYNCHRONIZATION PROFILE

Abstract:

This specification provides a means for a 3D display to support one

or more 3D glasses using Bluetooth technology, including
mechanisms for 3D glasses to discover and associate with a 3D
display, synchronization with a timing signal from the 3D display, and
the format of messages between the 3D display and the 3D glasses.

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1 Introduction
1.1 Scope
The 3D Synchronization Profile specifies the synchronization behavior of a Bluetooth 3D
system consisting of a single 3D display and one or more pairs of 3D glasses that
associate and synchronize with the 3D display. The user’s stereoscopic 3D experience
is delivered by showing different images to the left and right eyes. The 3D glasses use
shutter synchronization information transmitted from the 3D display to control the
shutters such that the left image is shown only to the left eye and the right image is
shown only to the right eye, when 3D content is being displayed.

1.2 Conformance
If conformance to this Profile is claimed, all capabilities indicated as mandatory for this
Profile shall be supported in the specified manner (process-mandatory). This also
applies for all optional and conditional capabilities for which support is indicated. All
mandatory capabilities, and optional and conditional capabilities for which support is
indicated, are subject to verification as part of the Bluetooth Qualification Program.

1.3 Symbols, Conventions, and Definitions

The following nomenclature and abbreviations are used in this document:
• 3DD – Bluetooth 3D Display
• 3DG – Bluetooth 3D Glasses
• Bluetooth 3D Display – a display device implementing the Bluetooth 3D
Synchronization Profile that is capable of signaling to Bluetooth 3D Glasses a
sequence of two temporally-separated image streams that can be directed to left
and right eyes to simulate a 3D stereoscopic viewing experience or optionally
directed to both eyes for two different groups of viewers allowing each group to see
a different 2D image stream on the same display.
• Bluetooth 3D Glasses – a pair of lens shutter glasses implementing the Bluetooth 3D
Synchronization Profile that is capable of optically de-multiplexing the temporally-
interleaved image streams of a Bluetooth 3D Display and either directing the image
streams to left and right eyes to simulate a 3D stereoscopic viewing experience or, if
optionally implemented, allowing one 2D image stream to be viewed by both eyes
while the other 2D image stream is blocked.
• Frame Sync – signal used in 3D displays for video frame display timing
synchronization alignment, where a frame is defined as a complete set of
corresponding right and left images1.

1In Dual View mode (see section 2.5) a frame is a full set of corresponding images from two distinct 2D
image streams being viewed simultaneously.

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• Legacy 3DD – a 3D display implementing the Reference Protocol defined in section

12.
• Legacy 3DG – a pair of 3D glasses implementing the Reference Protocol defined in
section 12.
• Synchronization – the act by a 3DG of receiving timing information from the 3DD to
adjust the shuttering of the left and right lens shutters in time with the display of a
sequence of two temporally separated image streams on the 3DD.

1.4 Profile Dependencies

This profile has three sub-functions. The mandatory Association function uses the
General Inquiry Procedure of GAP. The mandatory 3D Broadcast function uses the
Core Connectionless Slave Broadcast Feature in the Controller. The optional 3D
Communications Channel uses L2CAP. Additional details on Bluetooth Core
Specification [1] dependencies are described in section 10.

3D Sync Profile
Association
3D Communications
GAP SDP 3D Broadcast
L2CAP
HCI
BB
RF

Figure 1.1: 3D Synchronization Profile – Layers

1.5 Bluetooth Specification Release Compatibility

This profile is compatible with:
- Core Specification addendum 4 combined with Bluetooth Core Specification Version 3.0 + HS, OR
- Core Specification addendum 4 combined with Bluetooth Core Specification 4.0, OR
- Bluetooth Core Specifications Version 4.1 and later.

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2 Profile Overview
2.1 Profile Operation
The 3D Synchronization Profile supports the operation of a Bluetooth 3D System
consisting of a single 3D display (3DD) and one or more 3D glasses (3DG) as shown in
Figure 2.1.

Figure 2.1: Bluetooth 3D System

The Bluetooth 3D Synchronization Profile operates as follows.

• The 3DG selects a 3DD on which to view 3D content through Proximity Association.
• The 3DG optionally uses the 3D Communications Channel to send Association
Notification and/or its Battery Level information to the 3DD via a 3DG Connection
Announcement message.
• The 3DD time stamps occurrences of its image display Frame Sync using its native
Bluetooth clock. The 3DD also measures average Frame Sync period in units of
1/256 of a microsecond
• Consistent with the Bluetooth piconet definition, the 3DG’s Bluetooth clock is
synchronized with the 3DD’s native Bluetooth clock.
• The 3DD broadcasts to the 3DG via a 3D Broadcast Message the relationship of
Frame Sync timing to the 3DD’s native Bluetooth clock, the frame periods, and the
lens shutter control offsets relative to the Frame Sync. All timing uses the 3DD’s
native Bluetooth clock as the timing reference.
• The 3DD also provides periodic broadcast instants to the 3DG allowing the 3DG to
limit reception to these periods.
• The 3DG receives timing information from the 3D Broadcast Message and uses this
information to control the left and right lens shutters in synchronization with the 3DD
left and right eye display images. If the 3DG loses reception of the 3D Broadcast, the
3DG continues synchronized lens shutter operation while its lens shutter control
timing error is within an acceptable range. Once lens shutter control timing error
exceeds this threshold, the 3DG opens both lens shutters.

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2.2 Profile Roles

This profile defines two roles:
• The 3DD displays the images in a 3D system. In addition to displaying the images, it
performs the following additional functions:
− represents the Frame Sync timing in terms of its native Bluetooth clock (the 3DD
native Bluetooth clock serves as the reference time for all 3DGs that are
synchronized to its 3D Broadcast);
− broadcasts the Frame Sync timing, frame periods, and lens shutter control timing
information in the 3D Broadcast Message;
− is discoverable and identifiable by and synchronizable with the 3DG as a display
source of 3D content; and
− may be connectable to receive 3D Communications Channel information from
the 3DG.
• The 3DG synchronizes with the sequential left eye/right eye image streams,
displaying the left image to the left eye and right image to the right eye. In this
profile, the 3DG performs the following additional functions:
− discovers and synchronizes with a 3DD to associate with (Proximity Association);
− optionally informs the associated 3DD of such association over the 3D
Communications Channel (Association Notification) or via Legacy Association
Notification;
− optionally informs the associated 3DD of the 3DG battery level over the 3D
Communications Channel (Battery Level Reporting);
− receives and decodes timing information contained in the 3D Broadcast Message
from the 3DD; and
− uses timing information from the 3D Broadcast Message to control the left and
right eye lens shutters.

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2.3 System Block Diagram

Figure 2.2: Bluetooth 3D Synchronization Profile System Diagram

2.4 System Timing

The 3DD sequentially presents two distinct images, one for the left eye and one for the
right eye, separated in time. The 3DD broadcasts timing information related to its native
Bluetooth clock as follows:
• the Frame Sync Instant, transmitted in units of the 3DD native Bluetooth clock (this
may correspond to the rising edge of a Frame Sync signal);
• the frame period, transmitted in units of 1/256 microseconds; and
• the left and right image display timings, transmitted as time offsets to the Frame
Sync Instant.
Each 3DG, worn by the viewer, synchronizes with the 3DD and only allows light to pass
through the viewer’s left or right eye when the corresponding image is being displayed.
Figure 2.3 provides a sample timeline of the above operations. Note: This is a simplified
figure; actual implementations will vary in timing, may have black screen periods when
no image is displayed, etc. Such details are outside the scope of this document.

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Display Left Image Display Ready Right Image Display

for Viewing Ready for Viewing

Frame Sync

Left
Shutter Shutter Open Shutter Closed

Right
Shutter Shutter Closed Shutter Open

tLO
tLC
tRO
tRC

tLS

Figure 2.3: 3D System Timing

• tLS – 3DD starts displaying the left image

• tLO – the left lens shutter opens
• tLC – the left lens shutter closes
• tRO – the right lens shutter opens
• tRC – the right lens shutter closes

2.5 Dual View Mode

Instead of displaying two image streams intended for the left and right eyes, the 3DD
can display two distinct 2D image streams to two different 3DGs or two different sets of
3DGs. Possible uses of such a method include the following examples.
• Two people (or groups) watching two different shows on the same 3DD.
• Two people playing a video game with each player having a different 2D view of the
game world.
The lens shutter offset parameters transmitted by the 3DD are interpreted by the 3DG in
Dual View mode as shown in Figure 2.4.

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Video Stream 1 Video Stream 2

3DD Ready for Viewing Ready for Viewing

Frame Sync

3DG Viewing Both Shutters Open Using Left

Both Shutters Closed
Video Stream 1 Shutter Timing

3DG Viewing Both Shutters Closed

Both Shutters Open Using Right
Video Stream 2 Shutter Timing

Figure 2.4: Dual Video Stream (2D) System Timing

2.6 Profile Operations

This profile defines a number of operations that are summarized below. These
operations are described in more detail in latter sections of this document.

2.6.1 Frame Sync Capture

The 3DD captures specific occurrences of the Frame Sync Instant in units of its native
Bluetooth clock.

2.6.2 Proximity Association

Proximity Association is used by the 3DG to discover nearby 3DDs and select a 3DD for
synchronized operation.

2.6.3 3DG Connection Announcement

The 3DG Connection Announcement is a message sent by the 3DG to a 3DD
containing information concerning Association Notification and Battery Level Reporting.

2.6.4 Association Notification Transmission and Reception

Association Notification is used by the 3DG to notify the 3DD (selected via Proximity
Association) that the 3DG will synchronize to the 3DD’s 3D Broadcast. The 3DG
delivers this information as part of the 3DG Connection Announcement message sent
over the 3D Communications Channel.

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2.6.5 Legacy Association Notification Transmission

Legacy Association Notification Transmission is used by the 3DG to send the Legacy
Association Notification message to notify a Legacy 3DD (selected via Proximity
Association) that the 3DG will synchronize to a Legacy 3DD’s 3D Broadcast. The 3DG
delivers this information using the Legacy Association Notification feature.

2.6.6 Reference Protocol Association Notification Reception

Reference Protocol Association Notification Reception is used by the 3DD to receive the
Reference Protocol Association Notification message that is sent by a Legacy 3DG to
notify a Legacy 3DD (or in this case a 3DD) that it has successfully completed Proximity
Association with it and will synchronize to its 3D Broadcast.

2.6.7 Battery Level Reporting

Battery Level Reporting may be used by the 3DG to deliver its current battery level
information to the 3DD to which it is associated. The 3DG delivers this information as
part of the 3DG Connection Announcement message sent over the 3D Communications
Channel.

2.6.8 3D Broadcast Message

The 3DD transmits a set of parameters that define the Frame Sync timing, frame rate,
and lens shutter control offsets to the 3DGs via a 3D Broadcast Message. The 3D
Broadcast Message also conveys reference time (i.e., 3DD native Bluetooth clock)
synchronization in the system.

2.6.9 Shutter Control

The 3DG uses information from the 3D Broadcast Message to control the opening and
closing of the left and right lens shutters.

2.6.10 Profile Operations Summary

Table 2.1 summarizes the profile operations, their applicability to the 3DD or 3DG roles,
and whether they are optional, mandatory, or not applicable for each role.
Operation 3DD 3DG
Frame Sync Capture M X
Proximity Association Initiation X M
Proximity Association Response M X
Legacy Association Notification Transmission X O
Reference Protocol Association Notification Reception O X
3DG Connection Announcement Transmission X C.1
3DG Connection Announcement Reception C.2 X
Battery Level Reporting Transmission X C.3
Battery Level Reporting Reception C.4 X

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Operation 3DD 3DG

Association Notification Transmission X C.5
Association Notification Reception C.6 X
3D Broadcast Message Transmission M X
3D Broadcast Message Reception X M
Shutter Control X M
Table 2.1: 3D System Roles And Operations
• M – Mandatory
• O – Optional
• X – Excluded
• C.1: Mandatory if Legacy Association Notification Transmission is supported,
otherwise optional
• C.2: Mandatory if Reference Protocol Association Notification Reception is
supported, otherwise optional
• C.3: Optional if 3DG Connection Announcement Transmission is supported,
otherwise excluded
• C.4: Optional if 3DG Connection Announcement Reception is supported, otherwise
excluded
• C.5: Mandatory if Legacy Association Notification Transmission or Battery Level
Reporting Transmission is supported, otherwise optional if 3DG Connection
Announcement Transmission is supported, otherwise excluded
• C.6 Mandatory if Reference Protocol Association Notification Reception or Battery
Level Reporting Reception is supported, otherwise optional if 3DG Connection
Announcement Reception is supported, otherwise excluded

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3 Use Case Scenarios

This section describes some typical use case scenarios for 3D products implementing
the Bluetooth 3D Synchronization Profile, including products that optionally support
backward compatibility with Legacy 3DD and 3DG products. The Bluetooth 3D products
illustrated in this section, along with the description of their optional features and user
interfaces, may differ from actual Bluetooth 3D products.

3.1 Use Case 1: Using new Bluetooth 3D display with new Bluetooth
3D glasses
In this use case, the user buys a new Bluetooth 3DD and a new pair of Bluetooth 3DG
as shown in Figure 3.1.

Figure 3.1: New Bluetooth 3D Display used with New Bluetooth 3D Glasses
The user unboxes, sets up, and powers on the new Bluetooth 3DD and unboxes and
powers on the new Bluetooth 3DG. The user then holds the 3DG near the 3DD and
presses the power button on the 3DG for 3 seconds. This causes the 3DG to begin
searching for nearby 3DDs. The 3DG finds the 3DD and successfully completes
Proximity Association with this 3DD. The 3DG then sends a 3DG Connection
Announcement Message that includes the Association Notification and its Battery Level
Report indicating 85% battery level remaining. Once the 3DD receives and decodes this
3DG Connection Announcement Message, it generates a user advisory on its 3D
display screen stating, “3D glasses are now associated and have 85% battery capacity
remaining”.
The user then begins playing a 3D program on the 3DD and the 3DD begins
transmitting its 3D Broadcast Message that contains the lens shutter synchronization
timing information for the displayed 3D video images. The 3DG begins receiving these
3D Broadcast Messages and uses the timing information in the message to control the
opening and closing of the left eye and right eye lens shutters, which allows the user to
watch the 3D stereoscopic program.
The lens shutters on the 3DG stay synchronized with the 3DD as long as 3D content is
being displayed and the 3DG are in range of the 3DD’s 3D Broadcasts. If the user walks
out of range of the 3DD’s 3D Broadcast or the user switches to watching a 2D program

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on the 3DD, the 3DG lens shutters for both eyes will open (2D Mode). After some period
of time in the 2D Mode, the 3DG will automatically power off.

3.2 Use Case 2: Using new Bluetooth 3D display with Legacy 3D

glasses
In this use case, the user buys a new Bluetooth 3DD that supports backward
compatibility with Legacy 3DGs. The user wants to use his new 3DD with his Legacy
3DG as shown in Figure 3.2.

Figure 3.2: New Bluetooth 3D Display used with Legacy 3D Glasses

The user goes through the same steps to associate his Legacy 3DG with his new
Bluetooth 3DD as described in Use Case 1 above. Upon successful Proximity
Association, the Legacy 3DG sends Reference Protocol Association Notification, which
the new Bluetooth 3DD receives and then generates a user advisory on its 3D display
screen stating ”3D glasses are now associated”. Upon playing a 3D program on the
3DD, the Legacy 3DG receive the 3D Broadcast Message and use the information
contained in it to synchronize to the 3DD as described in Use Case 1 above.

3.3 Use Case 3: Using a Legacy 3D display with new Bluetooth 3D

glasses
In this use case, the user buys a new pair of Bluetooth 3DG that supports backward
compatibility with Legacy 3DDs. The user wants to use these new 3DG with his Legacy
3DD as shown in Figure 3.3.

Figure 3.3: Legacy 3D Display used with New Bluetooth 3D Glasses

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The user goes through the same steps to associate his new Bluetooth 3DG with his
Legacy 3DD as described in Use Case 1 above. Upon successful Proximity Association,
the new 3DG sends Legacy Association Notification, which the Legacy 3DD receives,
recognizes as Reference Protocol Association Notification, and then generates a user
advisory on its 3D display screen stating ”3D glasses are now associated”. Upon
playing a 3D program on the Legacy 3DD, the new 3DG receive the 3D Broadcast
Message and use the information contained in it to synchronize to the 3DD as described
in Use Case 1 above.

3.4 Use Case 4: Using new Bluetooth 3D display and new Bluetooth
3D glasses from different manufacturers
In this use case, the user buys a new Bluetooth 3DD and a pair of Bluetooth 3DG from
Manufacturer A and an additional pair of Bluetooth 3DG from Manufacturer B, as shown
in Figure 3.4.

Figure 3.4: New Bluetooth 3D Display used with New Bluetooth 3D Glasses from different Manufacturers
The user goes through the same steps to associate each pair of new Bluetooth 3DG
with his new Bluetooth 3DD as described in Use Case 1 above. After each pair of 3DG
successfully complete Proximity Association with the 3DD, each 3DG sends its
Association Notification, which the 3DD receives and then generates a user advisory on
its 3D display screen stating ”3D glasses are now associated”. Upon playing a 3D
program on the 3DD, both 3DGs receive the 3D Broadcast Message and use the
information contained in it to synchronize to the 3DD as described in Use Case 1 above.

3.5 Use Case 5: Using Bluetooth 3D display with unlimited number of

Bluetooth 3D glasses
In this use case, a multiplex theater operates a Bluetooth 3D digital cinema projection
system with 500 pairs of Bluetooth 3DGs. Since the system uses the Bluetooth 3D
Synchronization Profile, the theater allows movie audiences to bring their own Bluetooth
3DG from home to use in the 3D digital cinema as shown in Figure 3.5.

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Figure 3.5: New Bluetooth 3D Digital Cinema System used with large number of Bluetooth 3D Glasses
The multiplex theater owner purchases and has installed a new Bluetooth 3D digital
cinema projection system in Theater 1, which was ordered with 500 pairs of Bluetooth
3DG that were associated with this Bluetooth 3D projection system at the factory. These
Bluetooth 3DGs are powered on and provided to moviegoers entering Theater 1.
Moviegoers who want to use and have brought their own Bluetooth 3DG from home are
directed to a special area in Theater 1 where they are instructed to power on and
associate their Bluetooth 3DG with Theater 1’s Bluetooth 3D projection system.
When the 3D movie begins playing in Theater 1, the Bluetooth 3DGs worn by
moviegoers in Theater 1 begin receiving and synchronizing to the 3D Broadcast
Message from the Bluetooth 3D projection system in Theater 1. These 3DGs disregard
3D Broadcast Message transmissions from other Bluetooth 3D projection systems in the
multiplex.
When moviegoers who brought their own Bluetooth 3DG to the cinema return home,
they can associate their 3DG again with their home 3DD in the same manner as
described in Use Case 1 above.

3.6 Use Case 6: Multi-profile Bluetooth-enabled Living Room

In this use case, the user buys a new Bluetooth 3DD, a new pair of Bluetooth 3DG, a
new Bluetooth universal remote control, and some new Bluetooth stereo headphones
for use in his Living Room as shown in Figure 3.6.

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Figure 3.6: Multi-profile Bluetooth-enabled Living Room

The user successfully associates his Bluetooth 3DG with his Bluetooth 3DD as
described in Use Case 1. The user then follows the instructions to pair his Bluetooth
3DD with both his Bluetooth Remote Control, which in this example implements the A/V
Remote Control Profile (AVRCP), and his Bluetooth Stereo Headphones, which in this
example implements the Advanced Audio Distribution Profile (A2DP).
The user then uses his Bluetooth Remote Control that has connected with the 3DD to
select and play a 3D concert video program. The Bluetooth 3DG synchronize with the
3D Broadcast being transmitted from the Bluetooth 3DD. The user then powers up and
puts on his Bluetooth Stereo Headphones, which discover and connect to the
previously-paired Bluetooth 3DD thus allowing the user to watch and listen to the 3D
concert video program.

3.7 Use Case 7: Using Bluetooth 3D glasses with a Bluetooth 3D

display in a Multi-dwelling unit environment
In this use case, the tenant in Apartment 4 buys a new Bluetooth 3DD and 3DG for use
in his apartment located in a multi-dwelling housing unit where neighbors in surrounding
apartments also use Bluetooth 3DDs and 3DGs as shown in Figure 3.7.

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Figure 3.7: Using Bluetooth 3D Glasses and 3D Display in a Multi-Dwelling Unit

The user in Apartment 4 unboxes, sets up, and powers on his new Bluetooth 3DD and
Bluetooth 3DG. The user then holds his 3DG near his 3DD and presses the power
button on the 3DG for 3 seconds. This causes the 3DG to begin searching for nearby
3DDs. The 3DG discovers the user’s 3DD along with other operating 3DDs in his
neighbors’ apartments. However, the 3DG successfully completes Proximity Association
with the user’s 3DD, and ignores his neighbors’ 3DDs, since the user’s 3DD has the
strongest Bluetooth transmission.
Upon playing a 3D program, the user’s 3DD begins transmitting its 3D Broadcast
Message, which the user’s 3DG receives and synchronizes to. Because the user’s 3DG
are only associated to his 3DD, his 3DG ignore 3D Broadcast Messages being
transmitted by his neighbors’ 3DDs.

3.8 Use Case 8: Using Bluetooth 3D display and 3D glasses to view

two different 2D images on the same display (Dual View Mode)
In this use case, a user buys a new Bluetooth 3DD and two pairs of Bluetooth 3DG to
use with a 3D game console to play a 3D interactive game with a friend where the 3DD
is used to provide two different 2D views of the game play instead of a single 3D view
as shown in Figure 3.8.

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Figure 3.8: Using Bluetooth 3D Display and 3D Glasses for Dual View Mode Interactive Gaming
The user unboxes, sets up, powers on, and associates his new Bluetooth 3DD with two
pairs of Bluetooth 3DG. He then launches a 3D interactive game on his 3D game
console. In the game setup menu, he places the 3D game in the Dual View Mode where
the game renders two different 2D video streams (“Player 1 View” & “Player 2 View”)
instead of the normal 3D stereoscopic video streams (”Left Eye View” & ”Right Eye
View”).
The user moves the 3D/2D Dual View Mode switch on his 3DG from the ”3D” position to
the ”2D-View 1” position. On his friend’s 3DG, he moves the 3D/2D Dual View Mode
switch from the ”3D” position to the ”2D-View 2” position.
Once the Dual View interactive game starts playing, the 3DD sends 3D Broadcast
Messages causing the both left and right lens shutters on Player 1’s 3DG to open during
the normal ”Left Eye” view and to close on the normal ”Right Eye” view. This allows
Player 1 to only see the 2D ”Player 1 View” being displayed on the 3DD during the
normal ”Left Eye” display time. On Player 2’s 3DG, both the left and right lens shutters
open during the normal ”Right Eye” view and to close on the normal ”Left Eye” view.
This allows Player 2 to only see the 2D ”Player 2 View” being displayed on the 3DD
during the normal ”Right Eye” display time.
When the Dual View interactive gaming session ends, the user moves the 3D/2D Dual
View Mode switch back to the ”3D” Mode on both pairs of 3DGs so they are ready again
to be used for viewing normal 3D stereoscopic content.

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4 Frame Sync Capture

4.1 Frame Sync Capture Overview
The 3DD Frame Sync signal provides timing information about the displayed image.
This section will discuss the capture and conversion of the Frame Sync timing to the
system reference time, i.e., the 3DD native Bluetooth Clock.

4.1.1 Frame Sync Timing – An Example

A possible implementation of the Frame Sync signal is shown in Figure 4.1. In this
implementation, the rising edge of Frame Sync occurs at the start of the left image
display and the falling edge of Frame Sync occurs at the start of the right image display.
The images are displayed for the same amount of time, i.e., the Frame Sync signal is a
square wave. Other implementations of Frame Sync are possible, e.g., a pulse when
the left image is drawn, separate sync signals for left and right images, etc. but it is
assumed that the 3DD is able to effectively access or emulate a periodic Frame Sync
signal which indicates when a specific phase occurs within each frame.

Display Left Image Display Right Image Display

Frame Sync

Frame Period

Figure 4.1: Frame Sync Timing

4.1.2 Frame Sync Timing Conversion to Native Bluetooth Clock

The 3DD shall measure Frame Sync timing with respect to its native Bluetooth clock.
Timing conversion may be performed using the rising or falling edge of Frame Sync or
any convenient signal that provides the same timing conversion result. Depending on
the measured signal, some offset may need to be added to determine the start of
Left/Right Image Displays; such an adjustment is left to the implementation.

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Left Image Display Right Image Display

Frame Sync Period

Frame Sync
Signal

3DD Bluetooth Clock 3DD Bluetooth Clock

Figure 4.2: Frame Sync Conversion to Native Bluetooth Clock

Figure 4.2 is an example of how the conversion works. This figure assumes that the
rising edge of the Frame Sync signal indicates the start of the Left Image Display frame
and the falling edge indicates the start of the Right Image Display frame. When the
rising edge of Frame Sync occurs, the 3DD captures and stores the current value of its
native Bluetooth clock (CLK[27:0]) and also the microsecond phase.
The action of capturing the native Bluetooth clock value may be performed by hardware
(HW), interrupt-driven firmware (FW), or some combination of HW and FW, and is up to
the implementation. A Bluetooth device with support for the Triggered Clock Capture
Core feature may also be used; see section 4.1.2.2 for more information.

4.1.2.1 Frame Sync Instant – Resolution and Accuracy

The measurement of the Frame Sync Instant in relation to the 3DD native Bluetooth
clock shall be performed with a minimum resolution of 1 µs. The accuracy, which is
defined to be the maximum error between the native Bluetooth clock value at the time of
the rising edge of Frame Sync and the reported Bluetooth clock value, shall be ±5 µs.

4.1.2.2 Use of Triggered Clock Capture Core Feature

The Triggered Clock Capture Core feature [2] may be used to measure the Frame Sync
timing in relation to the native Bluetooth clock. In such an implementation a Bluetooth
Controller supporting the Triggered Clock Capture feature with the required accuracy
shall be used. The Bluetooth Controller will convert the external Frame Sync to its
native Bluetooth clock and provide this information to the Bluetooth Host.

4.1.3 Frame Sync Period Calculation

The 3DD shall also calculate the period of the Frame Sync in terms of the native
Bluetooth clock. Single period measurement may be used for this purpose, in which
case the period is simply the difference in the observed native Bluetooth clock values
between two consecutive Frame Sync instants. Another approach is to average over a
number of Frame Sync periods, as follows:
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Favg = (Bn - Bm)/(n-m)

Where:
• Favg is the average Frame Period
• m, n are the mth and nth Frame Sync instants, n > m
• Bn, Bm are the 3DD native Bluetooth clock values (plus phase) at times n and m
respectively
A running average may also be used.
When the Frame Sync Period is greater than 40,000 µs, the reported values for the
Frame Sync Period and the Frame Sync Period Fraction in the 3D Broadcast Message
shall be set to 0.

4.1.3.1 Frame Sync Period – Resolution and Accuracy

Frame Sync Period shall be calculated with a minimum resolution of 1/256 µs and an
accuracy of ±1 µs. The accuracy shall be defined as the maximum Frame Sync Period
timing error. Note: The Bluetooth clock reference in the 3DD must have an accuracy of
±20 parts per million (ppm) or better, as specified in the Bluetooth Core Specification [1]
in order to achieve end-to-end 3D system synchronization timing accuracy.
The Frame Sync Period is used by the 3DG to continue lens shutter operation in
between receptions of the 3D Broadcasts and to estimate the Frame Sync timing when
the 3DG misses one or more 3D Broadcasts. The resolution and accuracy of the
calculated Frame Sync Period allows the 3DG to continue lens shutter control
operations for a longer period of time reducing the need to synchronize to every 3D
Broadcast.

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5 Proximity Association
Proximity Association is the procedure by which the 3DG discovers a nearby 3DD,
selects a 3DD to operate with, and possibly stores this selection for future operation.
The following is an overview of the Proximity Association procedure.
1. 3DD is configured for Proximity Association as specified in section 5.2.
2. User action triggers Proximity Association on 3DG.
3. 3DG discovers nearby 3DDs using the rules specified in section 5.3.
4. 3DG selects one of the nearby 3DD to synchronize with using the rules described
in section 5.3.

5.1 Data Format

This section describes the format and contents of the fields/data used in the Proximity
Association procedure.

5.1.1 Class of Device

Class of Device is provided by the 3DD in an Inquiry Response. A 3DG shall not filter on
Class of Device as part of Proximity Association. A 3DD shall send the Class of Device
as specified in Table 5.1 and in the Bluetooth Assigned Numbers – Baseband [3] when
initiating Proximity Association with Legacy 3DG.
Field Value Description
00000000000b or Unspecified or
Major Service Class
00001000000b Capturing 2
Major Device Class 00100b Audio/Video
Minor Device Class 001111b Video Display and Loud Speaker
Table 5.1: Class of Device field

5.1.2 EIR Data Types

The 3DD shall include the three EIR data types specified in sections 5.1.2.1, 5.1.2.2,
and 5.1.2.3 in its EIR data. These data types may be included in any order and may be
interspersed with other EIR data types, except as noted in section 5.1.2.2.

5.1.2.1 3D Information

The 3DD shall include a section in its EIR data providing 3D Synchronization Profile
specific information. The data structure of this EIR data is specified in the Bluetooth

2Setting the Capturing service class flag is required by the A2DP specification for devices supporting the
Advanced Audio Distribution Profile (A2DP) source role. See the A2DP specification.

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Core Specification [1] and is described along with the Profile-specific 3D Information
data in Table 5.2.
Field Position Type Value Notes
Length of 3D Information EIR Data Type
ID and Profile-specific data section.
Length Byte 0 UINT8 >= 3 Current version of this Profile has a
length of 3 but may be extended in a
future revision.
3D Information EIR
Byte 1 UINT8 0x3D Bluetooth assigned number
Data Type ID
Association 0 – Not supported
Byte 2, bit 0 Bit
Notification 1 – Supported
0 – Not Supported
1 – Supported
Battery Level
Byte 2, bit 1 Bit
Reporting
The value shall be set to 0 if the
Association Notification is set to 0.
Send Battery Level Byte 2, bit 2 Bit 0 – 3DD requests 3DG to not send a
Report on Start-up 3DG Connection Announcement
Synchronization Message with Battery Level Report
on Start-up Synchronization.
1 – 3DD requests 3DG to send a 3DG
Connection Announcement
Message with Battery Level Report
on Start-up Synchronization.

The value shall be set to 0 if the Battery

Level Reporting is set to 0.
Reserved Byte 2, bit 3 Bit 0
Reserved Byte 2, bit 4 Bit 0
Reserved Byte 2, bit 5 Bit 0
Reserved Byte 2, bit 6 Bit 0
0 – normal operating mode
Factory Test Mode Byte 2, bit 7 Bit 0
1 – vendor-defined factory test mode
In dB. Maximum allowable path
attenuation from 3DD to 3DG. Greater
60-100
Path Loss Threshold Byte 3 UINT8 attenuation than this number will inform
(typical)
the 3DG that it is too far away and to
look for another 3DD.
Table 5.2: 3D Information EIR Data
Future versions of this EIR data may be extended to carry additional bytes in the Profile-
specific 3D Information data section. Therefore, 3DG compliant with this version of the
Profile specification shall ignore any additional data beyond what is specified in Table
5.2, if present.

5.1.2.2 Legacy 3D Information

The 3DD shall include a section in its EIR data for Legacy 3D Information that is
formatted as Manufacturer Specific Data type as specified in Table 5.3. It shall be the
first Manufacturer Specific Data in the EIR packet, preceding any other Manufacturer
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Specific Data. This is necessary for backward compatibility with the Reference Protocol
as some Legacy 3DG only look at the first Manufacturer Specific Data in the EIR data. It
should be noted that the requirement of the 3DD to include the Legacy 3D Information
in its EIR data may become optional in a future version of the Profile specification.
The data structure of this EIR data is specified in the Bluetooth Core Specification [1]
and is described along with the specific Legacy 3D Information in Table 5.3.
Field Position Type Value Notes
Length-Manufacturer Length of manufacturer specific
Byte 0 UINT8 6
Specific Data section
Manufacturer
Byte 1 UINT8 0xFF Bluetooth assigned number
Specific
Fixed ID Byte 2-3 UNIT16 0x000F Fixed value (Broadcom)
Shall be set to 0. If this field is not 0,
Fixed Byte 4 UINT8 0
Legacy 3DG will skip this section
1 – 3D supported
3D Capable TV Byte 5, bit 0 Bit 1
0 – 3D not supported
Ignored Byte 5, bit 1 Bit 0
Ignored Byte 5, bit 2 Bit 0
Ignored Byte 5, bit 3 Bit 0
Fixed Byte 5, bit 4 Bit 0 Shall be set to 0.
Ignored Byte 5, bit 5 Bit 0
Fixed Byte 5, bit 6 Bit 0 Shall be set to 0.
0 – 3DD in normal operating mode
Test Mode Byte 5, bit 7 Bit 0 1 – 3DD is in factory Legacy 3DG test
mode(Note 1)
In dB. Maximum allowable path
attenuation from 3DD to Legacy 3DG.
60-100 Greater attenuation than this number
Path Loss Threshold Byte 6 UINT8
(typical) will inform the Legacy 3DG that it is
too far away and to look for another
3DD
Table 5.3: Legacy 3D Information
Note 1: Factory test mode is for manufacturing convenience. Support of this mode and device behavior in
this mode is up to the manufacturer and outside the scope of this document.

5.1.2.3 TX Power Level

The 3DD shall include a TX Power Level data type in its EIR data (see [4]). Note: For
compatibility with Legacy 3DGs, the use of negative TX power values (i.e., below 0
dBm) should be avoided.

5.2 3DD Configuration for Proximity Association

The 3DD support of Proximity Association requires the following configuration steps:
1. inclusion of EIR data types as specified in section 5.1.2, and
2. the 3DD is in the general discoverable mode.

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For an improved user experience, it is recommended that the 3DD be configured for
Proximity Association as the factory default setting.

5.3 Proximity Association Procedure

The Proximity Association procedure is executed by the 3DG. This procedure is
described below.
1. User interaction triggers Proximity Association on the 3DG.
a. User interaction may be accomplished using a push button, a motion or
touch sensor, or some other human interaction with the 3DG.
2. The 3DG performs a general inquiry with a duration of 5.12 seconds but no
longer than 10 minutes.
3. While the general inquiry is ongoing, the 3DG shall create a list of nearby
Bluetooth devices, ignoring their Class of Device, that satisfy the following criteria
and obtain the EIR receive power for each device in the list.
a. A correctly formatted EIR packet is received from the responder that
includes the 3D Information data type and the TX Power Level data type
as described in section 5.1.2, or in the case of a Legacy 3DD, the EIR
packet includes the Reference Protocol 3D Information data type as
specified in section 12.1.2 and the TX Power Level data type. When the
EIR packet contains both the Manufacturer Specific Data data type
containing Legacy 3D Information and the 3D Information EIR data type,
the Manufacturer Specific Data data type containing Legacy 3D
Information shall be ignored by the 3DG. If the Reference Protocol 3D
Information data type is received from a Legacy 3DD, the 3DG shall verify
that the “Multicast Capable” bit in this field is 1 and if not, the 3DG shall
ignore the response.
b. The calculated path loss for the EIR packet of the responder (Path Loss =
TX Power – RX EIR Power) is less than or equal to the Path Loss
Threshold specified in the responder’s EIR data.
4. At the end of the general inquiry, the 3DG shall select and commence Proximity
Association with the responder from the list of devices determined in Step 3 with
the lowest path loss. If no response is received that satisfies the criteria specified
in step 3, the 3DG may enter a low power state, repeat the general inquiry, or
take other action. If there are multiple responders with identical path loss that
satisfy the criteria specified in step 3, then it is implementation specific as to
which responder to select to complete Proximity Association.
5. After successfully completing Proximity Association, the 3DG shall store the 3D
Information data type or the Reference Protocol 3D Information data type may
attempt to synchronize to the 3D Broadcast defined in section 8, communicate
with the 3DD via the 3D Communications Channel or communicate with the
Legacy 3DD via Legacy Association Notification, or enter a low power state.

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The above procedure for Proximity Association between a 3DD and a 3DG is depicted
in Figure 5.1:

3DD 0 3DD N 3DG

3DD configured for 3DD configured for User action triggers

Proximity Association Proximity Association Proximity Association
(possibly at startup) (possibly at startup) on 3DG

Inquiry
FHS
EIR Response
(With 3D Data)

Inquiry
FHS
EIR Response
(With 3D Data)

Inquiry
FHS
EIR Response
(With 3D Data)

3DG selects 3DD with the

smallest path loss

Figure 5.1: Proximity Association

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6 3D Communications Channel
The 3D Communications Channel is used to send messages between the 3DD and
3DG. In this version of the profile, only a single message is defined, the 3DG
Connection Announcement, which is sent from the 3DG to the 3DD and contains the
Association Notification and Battery Level fields

3DD 3DG

3DG Establishes ACL Link to 3DD

3DG Connection Announcement

(unencrypted unicast connectionless L2CAP data)

Either Side Disconnects ACL Link

Figure 6.1: 3DG Connection Announcement on 3D Communications Channel

The following sequence of steps is used to send the 3DG Connection Announcement
message on the 3D Communications Channel.
• The 3DG shall establish an ACL link with the 3DD.
• The 3DG shall send the 3DG Connection Announcement as unicast traffic over
the connectionless L2CAP data channel. This Profile does not require encryption
of the 3DG Connection Announcement message.
• After the 3DG has transmitted the 3DG Connection Announcement message, the
3DD may initiate additional transactions, e.g., service discovery or utilizing other
services, which the 3DG may offer.
• Either side may disconnect the ACL link at this time.

6.1 3D Communications Channel Messages

Messages sent on the 3D Communications Channel shall use the G-frame format as
described in Volume 3, Part A, Section 3.2 of [1] and shall consist of a 3-byte length
message with first byte containing an opcode field followed by two bytes of information.
The PSM field in the packet shall be set to the fixed PSM value for the 3D
Synchronization Profile Communications Channel as defined in [3].
The following sections define the messages, which may be used over the 3D
Communications Channel. The G-frame header is not included in the definition of each

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message. The 3D Communications Channel Message Opcode field shall be the first
byte in the Information payload portion of the G-frame PDU.

6.2 3DG Connection Announcement Message Format

Table 6.1 shows the format of the 3DG Connection Announcement message from the
3DG to the 3DD.
Table 6.1: 3DG Connection Announcement Message Format
Field Position Type Value Notes
3D Byte 0 UINT8 0 = 3DG Connection
Communications Announcement message
Channel 1-255 = Reserved
Message Opcode
Association Byte 1, bit 0 Bit 0 = Connection not due to Whenever the User
Notification association Request for Battery
1 = Connection occurred due Level Display bit is set
to association to a value of 1, this
field shall be set to 0.
User Request for Byte 1, bit 1 Bit 0 = User has not made a Whenever the
Battery Level specific request to display Association
Display Battery Level Notification bit is set to
1 = User has made a specific a value of 1, this field
request to display Battery shall be set to 0.
Level
Reserved Byte 1, bits 2-7 000000b
Battery Level Byte 2 UINT8 0-100 = % of current charge Expresses the battery
level of battery charge level in linear
101-254 = reserved units of percentage
255 = Battery Level Reporting points.
not supported

6.3 Use Case – Association Notification

6.3.1 3DG Behavior
If Association Notification is supported by the 3DG and the 3DD has indicated support in
the Association Notification field in its 3D Information data type received over EIR, the
3DG shall send a 3DG Connection Announcement message to the 3DD with the
Association Notification bit set to the value 1 after completing Proximity Association with
the 3DD. Such 3DG Connection Announcement message may also include the Battery
Level report if supported by the 3DG.
If Association Notification is supported by the 3DG but the 3DD has indicated no
support for Association Notification in its 3D Information data type received over EIR,
the 3DG shall not send a 3DG Connection Announcement to the 3DD.

6.3.2 3DD Behavior

If Association Notification is supported by the 3DD,

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1) the 3DD shall parse the 3D Communications Channel Message Opcode to

confirm it is a valid 3DG Connection Announcement message and
2) upon receiving a 3DG Connection Announcement message with the Association
Notification bit set to a value of 1, the 3DD should display the association status
of the 3DG to the user if appropriate for the 3DD user interface.

6.4 Use Case – Battery Level Reporting

6.4.1 3DG Behavior
When the 3DG sends its Battery Level report, the 3DG’s current percentage of battery
level remaining shall be reported in the Battery Level field of the 3DG Connection
Announcement message.
If Battery Level Reporting is supported by the 3DG and the 3DD has indicated support
in the Battery Level Reporting field in its 3D Information data type received over EIR,
the 3DG may send its Battery Level report at any time to a 3DD.
If Battery Level Reporting is supported by the 3DG and the 3DD has indicated support
in the Battery Level Reporting field in its 3D Information data type received over EIR,
the 3DG shall send its Battery Level report in the following scenarios:
1) At the time of Association Notification, the 3DG shall send the Battery Level
information in the 3DG Connection Announcement message with the Association
Notification bit set to 1 and the User Request for Battery Level Display bit set to
0.
2) If the Send Battery Level Report on Start-up Synchronization bit specified in
section 5.1.2.1 is enabled by the 3DD, at the time the 3DG transitions from a
powered-off or stand-by mode to powered on and synchronized with the 3DD
(”Start-up Synchronization”), the 3DG shall send the Battery Level information in
the 3DG Connection Announcement with the Association Notification bit set to 0
and the User Request for Battery Level Display bit set to 0.
3) If the 3DG optionally implements the ability of a user action on the 3DG to
specifically request the 3DG to send its battery level, then when such user action
is initiated, the 3DG shall send the Battery Level information in the 3DG
Connection Announcement with the Association Notification bit sent to 0 and the
User Request for Battery Level Display bit set to 1.
If Battery Level Reporting is supported by the 3DG but the 3DD has indicated no
support for Battery Level Reporting in its 3D Information data type received over EIR,
the 3DG shall not send a 3DG Connection Announcement except when signaling
Association Notification.
If Battery Level Reporting is not supported by the 3DG, then the Battery Level field shall
be set to indicate ”Battery Level Reporting not supported” whenever the 3DG
Connection Announcement message is sent.

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In the case where the 3DG is a multi-profile implementation with both GATT Battery
Service support and Battery Level Reporting, the 3DG shall calculate the Battery Level
value reported in the 3DG Connection Announcement in the same way as used to
calculate the Battery Level value reported using the GATT Battery Service.

6.4.2 3DD Behavior

Upon receiving the 3DG Connection Announcement message containing a Battery
Level field with a value between 0 and 100, the 3DD may display the Battery Level
value to the user if appropriate for the 3DD user interface. If such 3DG Connection
Announcement message has the User Request for Battery Level Display bit set to 1, the
3DD should display the Battery Level value to the user.

6.5 3DDs without support for the 3D Communications Channel

A 3DD that does not support the 3D Communications Channel shall indicate in its 3D
Information data type that it does not support Association Notification and Battery Level
Reporting.
3DGs shall not send 3D Communications Channel messages to 3DDs that do not
support Association Notification.

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7 Association Notification with Legacy 3D Devices

For backward compatibility with Legacy 3DGs and Legacy 3DDs, a 3DG may optionally
support the Legacy Association Notification transmission as described in this section
and a 3DD may optionally support Reference Protocol Association Notification reception
as described in sections 12.1.3 and 12.1.4. The Legacy Association Notification
transmission shall only be used by a 3DG when Proximity Association occurs with a
Legacy 3DD.

7.1 Identification of Legacy 3D Devices

A 3DG can identify a Legacy 3DD by inspection of the EIR data field. If the EIR data
does not contain the 3D Information data type but does contain the Reference Protocol
EIR Data field, the 3DD is a Legacy 3DD.
A 3DD can only identify a Legacy 3DG by reception of the 3DG’s Reference Protocol
Association Notification message.

7.2 Reference Protocol Association Notification Reception

Reference Protocol Association Notification reception (as described in sections 12.1.3
and 12.1.4) may optionally be supported by a 3DD when a Legacy 3DG sends this
message to notify the 3DD that it has successfully completed Proximity Association with
the 3DD. This procedure consists of the following steps.
1. Legacy 3DG completes Proximity Association with a 3DD.
2. Legacy 3DG transmits the Reference Protocol Association Notification to notify
the selected 3DD that the Legacy 3DG has associated with the 3DD.
3. The 3DD receives the Reference Protocol Association Notification sent by the
Legacy 3DG but does not send any acknowledgement back to the Legacy 3DG
of successful reception of the Reference Protocol Association Notification.

7.3 Legacy Association Notification Transmission

Legacy Association Notification transmission (as described in section 7) may optionally
be supported by a 3DG to notify a Legacy 3DD that it has successfully completed
Proximity Association with the Legacy 3DD. This procedure consists of the following
steps.
1. 3DG completes Proximity Association with a Legacy 3DD.
2. 3DG executes the Legacy Association Notification procedure to notify the
selected Legacy 3DD that the 3DG has associated with the Legacy 3DD.
3. 3DG receives the Reference Protocol Association Notification Ack sent by the
Legacy 3DD after successfully receiving the 3DG’s Legacy Association
Notification.

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a. If the 3DG does not receive the Ack from the Legacy 3DD, the 3DG
continues the Legacy Association Notification procedure until the Ack is
received or at least 10.24 seconds elapse.
b. If the 3DG is not able to complete Step 3, then the Legacy Association
Notification transmission procedure is terminated.
The above procedure is depicted in Figure 7.1.

Legacy 3DD X 3DG

3DG has Associated with

Legacy 3DD X

Legacy Association Notification

Figure 7.1: Legacy Association Notification Transmission

7.4 Data Format

This section describes the format and contents of the data fields used in the Legacy
Association Notification procedure.

7.4.1 Legacy Association Notification Message

The format of the Legacy Association Notification message is shown in Table 7.1.
Field Position Type Value Notes
A pseudo-random value The value shall be
from 0 through ((2^48)–1) refreshed after
inclusive. each successful
3DG ID Bytes 0-5 UINT48
completion of
Proximity
Association.
Device 0: 3DG
Byte 6 UINT8
Type 1-255: Reserved
Reserved Bytes 7-16 0x00
Table 7.1: Legacy Association Notification Message Format
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7.5 3DD Requirements

A 3DD shall satisfy the following requirements when implementing the optional
Reference Protocol Association Notification reception feature:
1. 3DD shall support the reception of the Reference Protocol Association
Notification message transmitted by a Legacy 3DG as described in sections 7,
12.1.3, and 12.1.4.
2. 3DD shall support parsing of the Reference Protocol Association Notification
message as described in section 12.1.3.
3. Upon receiving the Reference Protocol Association Notification message, the
3DD should display the association status of the Legacy 3DG to the user if
appropriate for the 3DD user interface.

7.6 3DG Requirements

A 3DG shall satisfy the following requirements, when implementing the optional Legacy
Association Notification transmission feature:
1. 3DG shall support the transmission of the Legacy Association Notification
message to a Legacy 3DD as described in sections 7 and 12.1.4.
2. 3DG shall support the Legacy Association Notification message format described
in section 7.4.
3. Upon successful completion of Proximity Association with a Legacy 3DD, the
3DG shall transmit the Legacy Association Notification message to the selected
Legacy 3DD.

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8 3D Broadcast
The 3DD broadcasts 3D timing information, including Frame Sync Instant, Frame Sync
Period, and lens shutter open and close offsets, using the Connectionless Slave
Broadcast Core feature [2]. The 3DG uses the Connectionless Slave Broadcast core
feature to synchronize to the 3DD and receive this information for lens shutter control.

8.1 Connectionless Slave Broadcast Parameters

The Broadcast Period for Connectionless Slave Broadcast should be set to a value
between 50-100 ms. The Broadcast LT_ADDR value 1 shall be acquired after reset and
before any ACL connections are established.

8.2 Synchronization Train Parameters

Synchronization Train shall use GAP parameters unless noted below:
− Sync_Train_Duration should be 120 seconds or longer.

8.3 3D Broadcast Message Format

The format of the 3D Broadcast Message is shown in Table 8.1.
Field Position Type Value Notes
3DD Native
Byte 0 bit 0 to Bluetooth
Frame Sync Instant LSB = 625 µs
Byte 3 bit 2 Clock
Bits[27:1].
Byte 3 bits 3, 4,
Reserved 0
and 5
In the Dual View
Mode, the left
lens shutter
UINT32 offsets are
interpreted as
0 – 3D Mode
offsets for video
Video Mode Byte 3 bit 6 1 – Dual
stream 1 and the
View Mode
right lens shutter
offsets are
interpreted as
offsets for video
stream 2.
Reserved Byte 3 bit 7 0
Bluetooth clock
phase at Frame Sync Bytes 4,5 UINT16 0-624
Instant (µs)
Special value of
0xFFFF signals
Left lens shutter
Bytes 6,7 UINT16 0-65535 glasses are in 2D
open offset (µs)
mode and both
shutters shall be
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Field Position Type Value Notes

opened. When
the value of the
Frame Sync
Period is equal to
0, then this field
shall be set to
0xFFFF.
Left lens shutter
Bytes 8,9 UINT16 0-65535
close offset (µs)
Right lens shutter
Bytes 10,11 UINT16 0-65535
open offset (µs)
Right lens shutter
Bytes 12,13 UINT16 0-65535
close offset (µs)
Frame Sync Period The value shall
Bytes 14,15 UINT16 0-40000
(µs) not be > 40000.
The fractional part
Frame Sync Period
Byte 16 UINT8 0-255 of the Frame
Fraction (1/256 µs)
Sync Period
Table 8.1: 3D Broadcast Message Format

8.4 3DD Requirements

1. 3DD shall start the collection of Frame Sync Instant and Frame Sync Period as
described in section 4.
2. 3DD shall set up a Connectionless Slave Broadcast channel using the parameters
described in section 8.1.
3. 3DD shall format the 3D Broadcast Message as described in section 8.3.
a. The lens shutter open and close offsets shall be defined relative to the Frame
Sync Instant. The lens shutter open offsets shall represent the time when the
image displayed by the 3DD is ready for viewing by the 3DG. The lens shutter
close offsets shall represent the time when the image displayed by the 3DD
begins to transition from suitable for viewing to not suitable for viewing.
4. 3DD shall either continuously be in Synchronizable mode for the duration of the 3D
Broadcast, or enter Synchronizable mode for a period equal to or greater than that
specified in section 8.2 upon detecting a Slave Page Response Timeout event. 3DD
should ignore Slave Page Response Timeout events if it is already in
Synchronizable mode or if the 3D Broadcast is inactive.

8.5 3DG Requirements

1. 3DG shall perform Synchronization establishment with the 3DD with which it has
completed Proximity Association.
2. If Synchronization is unsuccessful, 3DG shall perform a Truncated Page
procedure with the 3DD with which it has completed Proximity Association and
then retry Synchronization establishment
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3. Within 500 ms after successfully completing Synchronization establishment, 3DG

shall set up to receive the Connectionless Slave Broadcast transmission for the
associated 3DD using the parameters for LT_ADDR 1 obtained from
Synchronization establishment.
4. 3DG shall receive 3D Broadcasts and decode the 3D Broadcast Message in
them using the format from section 8.3.
5. 3DG may skip receiving 3D Broadcasts to conserve power.
6. If the 3DG has skipped receiving 3D Broadcasts, but has not received them
during several recent attempts, it should stop skipping intervals and attempt to
receive every 3D Broadcast until a 3D Broadcast is received.
7. If the 3DG detects a significant loss of reception of the 3D Broadcast packets, it
should repeat Synchronization establishment with the 3DD with which it has
completed Proximity Association. The suggested threshold is 50% or greater
failure of attempts to receive a 3D Broadcast. This behavior is recommended to
facilitate dynamic AFH that might provide a solution to the loss of reception of the
3D Broadcast caused by RF interference.
8. 3DG shall use timing information from the 3D Broadcast Message to control the
left and right lens shutters.
9. If 3DG loses, and cannot re-establish, reception of the 3D Broadcasts, it shall
open both lens shutters when it has determined that the maximum shutter control
timing error has increased beyond 500 µs as specified in section 9.3.

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9 Shutter Timing Generation

The 3DG uses timing information from the 3D Broadcast Message to control the left and
right lens shutters.

9.1 Lens Shutter Delays

The left and right lens shutter control timing information in the 3D Broadcast Message
assumes idealized lens shutters opening and closing instantaneously. The
manufacturers of 3DG need to understand the transmissivity response characteristic of
their lens shutters and should compensate accordingly.

9.2 Supported Lens Shutter Frame Rates

3DG shall support the mandatory lens shutter frames rates per eye of 50 Hz and 59.94
Hz within a tolerance range of ±1%. 3DG should support a continuous, wide range of
lens shutter frame rates to allow for greater interoperability.
3DG shall open both lens shutters if any of the following conditions are met:
1. The 3D Broadcast Message informs a lens shutter frame rate that is outside the
supported lens shutter frame rate range of the 3DG.
2. The 3D Broadcast Message informs a lens shutter frame rate below 25
frames/second.

9.3 Lens Shutter Control Timing Accuracy

Actual testing of 3D systems has shown that when the synchronization timing error
between the 3DD displayed images and the 3DG lens shutters increases beyond 500
µs, this out-of-sync condition becomes visually noticeable to the typical viewer.
Therefore, if the maximum shutter control timing error has increased beyond 500 µs,
both the left and right lens shutters of the 3DG shall be opened and shall be kept open
until the 3DG has determined that the maximum timing error has decreased to ≤ 500 µs.

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10 Core Specification Dependencies

This section describes additional requirements beyond those defined in the Bluetooth
Core Specification [1] and the Bluetooth Core Specification Addendum 4 [2].

10.1 Link Manager Protocol (LMP) Requirements

This section describes LMP requirements for 3DD and 3DG beyond those defined in [2].
Feature Support in 3DD Support in 3DG
Connectionless Slave Broadcast
M X
– Master Operation
Connectionless Slave Broadcast
X M
– Slave Operation
Synchronization train M X
Synchronization Scan X M
Table 10.1: Link Manager Protocol Requirements

10.2 Logical Link Control and Adaptation Protocol (L2CAP)

Requirements
This section describes L2CAP requirements for 3DD and 3DG beyond those defined in
[2].

Feature Support in 3DD Support in 3DG

Unicast Connectionless Data

C.1 N/A
Reception
Unicast Connectionless Data
N/A C.2
Transmission
Table 10.2: Logical Link Control and Adaptation Protocol Requirements
C.1 Mandatory if Association Notification Reception or Battery Level Reporting Reception is supported,
otherwise optional.
C.2 Mandatory if Association Notification Transmission or Battery Level Reporting Transmission is
supported, otherwise optional.

10.3 Generic Access Profile (GAP) Requirements

This section describes GAP requirements for 3DD and 3DG beyond those defined in [2].
Feature Support in 3DD Support in 3DG
Synchronizable Mode M X
Non-Synchronizable Mode M M
Synchronization Establishment M M
Procedure
General Discoverable Mode M X
Connectable Mode C.1 X
Table 10.3: Generic Access Profile Requirements

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C.1 Mandatory IF (Association Notification Reception is supported OR Battery Level

Reporting Reception is supported OR 3DD is not continuously in Synchronizable mode);
otherwise optional.

10.4 Service Discovery Protocol (SDP) Requirements

The following service records are defined for the 3DD and 3DG roles of the 3D
Synchronization Profile. There shall be only one service record for each supported role.
The device shall support at least one service record on the device for the applicable
role(s) supported.

10.4.1 SDP record for the 3DD role

Item Definition Type Value Status Default
ServiceClassID List [Note 1] M
ServiceClass #0 UUID 3D Display [Note 1] M
ServiceName Displayable text String Service-provider defined O "3D Display"
name
Bluetooth Profile [Note 1] M
Descriptor List
Supported
Profile #0 UUID 3D Sync Profile [Note 1] M
Profiles
Param #0 Profile Version UINT16 0x0100 M
Table 10.4: SDP Record for 3DD Role
Note 1: For actual values for this field, please refer to the Bluetooth Assigned Numbers
section of the Bluetooth SIG website [3].

10.4.2 SDP record for the 3DG role

Item Definition Type Value Status Default

ServiceClassID List [Note 1] M

ServiceClass #0 UUID 3D Glasses [Note 1] M
ServiceName Displayable text String Service-provider defined O "3D
name Glasses"
Bluetooth Profile [Note 1] M
Descriptor List
Profile #0 Supported profiles UUID 3D Sync Profile [Note 1] M
Param #0 Profile version UINT16 0x0100 M
Table 10.5: SDP Record for 3DG Role
Note 1: For actual values for this field, please refer to the Bluetooth Assigned Numbers
section of the Bluetooth website [3].

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11 References
[1] Specification of the Bluetooth System, Core Package Version 3.0 + HS or 4.0 or later.
[2] Bluetooth Core Specification Addendum 4
[3] Bluetooth Assigned Numbers (http://www.bluetooth.org/assigned-numbers)
[4] Bluetooth Core Specification Supplement v2 or later

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12 Appendix: Reference Protocol

The Reference Protocol includes over-the-air interactions between one Legacy 3DD
and one or more pairs of Legacy 3DGs.
The Reference Protocol delivers the following four services.
• Association
• Synchronization establishment
• 3D synchronized operation
• External clock capture and generation

12.1 Association
During association, the Legacy 3DG (and the user) finds and selects the desired Legacy
3DD. This service requires two actions from the user:
1) Some action (such as a button press) to initiate the procedure at the Legacy
3DG.
2) Make sure the Legacy 3DG is physically close to the desired Legacy 3DD.
The Legacy 3DG responds to the above actions by associating with the Legacy 3DD
that exhibits the lowest path loss as calculated by the difference between the Legacy
3DD transmitted power (reported in the EIR) and the Legacy 3DG received power. Note
that the EIR transmitted from the Legacy 3DD also contains a path loss threshold that is
used by the Legacy 3DG to prevent it from associating with the Legacy 3DD unless the
path loss falls below this threshold.
The procedure requires three steps:
1. The Legacy 3DG sends a general inquiry and collects EIR data from all
responding devices that have a specific Class of Device as specified in section
12.1.1 and a correctly-formatted 3D EIR data type.
2. The Legacy 3DG calculates path loss for each Legacy 3DD. If one or more
Legacy 3DDs satisfy the path loss threshold, the Legacy 3DG selects the Legacy
3DD with the lowest path loss to associate with.
3. The Legacy 3DG sends a second general inquiry, waits for the EIR from the
selected Legacy 3DD, and responds with a Reference Protocol Association
Notification message.

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Top Level Sequence Diagram

Figure 12.1 illustrates how a Legacy 3DG associates with a Legacy 3DD.

Legacy 3DD Legacy 3DG

User action triggers

association on Legacy 3DG

Inquiry

FHS
EIR Response
(With Legacy 3D Data)

Legacy 3DG may look for

other Legacy 3DDs.
The following sequence
applies if the Legacy 3DG
selects this Legacy 3DD to
associate with.

Inquiry

FHS
EIR Response
(With Legacy 3D Data)

Association Notification

Ack
EIR Handshake Event
(Legacy 3DG Associated)
(Informative)

Figure 12.1: Association – Sequence Diagram

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12.1.1 FHS Packet Format

Table 12.1 specifies the detailed format of the FHS packet provided by the Legacy 3DD
to the Legacy 3DG in response to the inquiry. All fields in this packet are formatted,
transmitted, and processed according to the Bluetooth Core specification.
Field # of bits Value Notes Legacy 3DG Behavior
Parity Bits 34 derived from Legacy
3DD LAP
LAP 24 Legacy 3DD LAP
EIR 1 1
Un-defined 1 0
SR 2 01 R1 Legacy 3DG does not use this parameter
for association or Association Notification.
Reserved 2 00
UAP 8 Legacy 3DD UAP
NAP 16 Legacy 3DD NAP
Class of 24 0x00043C or Legacy 3DG only accepts these 2 values
device 0x08043C during association.
LT_ADDR 3 000
CLK27-2 26 Legacy 3DD CLK
Page scan 3 000
mode
Table 12.1: FHS packet format
Table 12.2 specifies the values to use for the Class of Device field.
Field Value Description
Major Service Class 00000000000b or Unspecified or
00001000000b Capturing
Major Device Class 00100b Audio/Video
Minor Device Class 001111b Video Display and Loud Speaker
Table 12.2: Class of Device field
12.1.2 Reference Protocol 3D Information EIR Data Format
Table 12.3 lists the Reference Protocol 3D Information data provided by the Legacy
3DD to the Legacy 3DG in an extended inquiry response (EIR). Note that Reference
Protocol 3D Information must appear somewhere in the EIR data, i.e., other EIR data
can and typically will also be provided.
Note also that the TX power parameter is a standard parameter in the table below and
is not part of the manufacturer specific data. This field must be present in EIR but does
not need to be immediately after the manufacturer specific section.

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EIR Data Field Type Value Notes Legacy 3DD Legacy 3DG
Type Behavior Notes Behavior
Compatibility
Manufacturer Length- UINT8 6 # of bytes in Required by
Specific Data Manufacturer this data Legacy 3DGs.
Manufacturer UINT8 0xFF Required by
Specific Legacy 3DGs.
Manufacturer UINT1 0x000F Broadcom Required by
6 (little endian) Legacy 3DGs.
Reserved UINT8 0 Must set to 0 Required by
Legacy 3DGs.
Multicast bit 0 1 1 – Multicast capable Required by
Capable TV 0 – Not multicast Legacy 3DGs
capable (set to 1).
Reserved bit 1 0 Ignored by
Legacy 3DGs.
Sending bit 2 0 1 - Legacy 3DD Ignored by
Sync Train sending sync trains Legacy 3DGs.
0 – Legacy 3DD not
sending sync trains
Remote bit 3 0 – no remote paired Ignored by
Paired 1 – remote paired Legacy 3DGs.
Showroom bit 4 0 – Showroom mode Required by
Mode disabled Legacy 3DGs.
1 – Showroom mode
enabled
Remote bit 5 0 – Not in remote Ignored by
Pairable pairable mode Legacy 3DGs.
Mode 1 – In remote pairable
mode
Reserved bit 6 0 Required by
Legacy 3DGs.
Test Mode bit 7 0 0 – Normal mode Used by Legacy
1 – Legacy 3DD is in 3DGs during
factory 3DG test factory testing.
mode. See Note 1
below
Path loss UINT8 60-100 In dB. See Required by
threshold Note 2 below Legacy 3DGs for
(typical) path loss
calculations.
Tx Power Length-TX UINT8 2 # of bytes in Required by
Level Power this data Legacy 3DGs.
TX Power ID UINT8 0x0A Assigned Required by
number Legacy 3DGs.
TX Power INT8 0-10 In dBm. See
Set to the default TX Required by
Value (typical) Note 3 below
power of the Legacy Legacy 3DGs.
3DD.
Table 12.3: Format of Reference Protocol 3D Information EIR Data from Legacy 3DD to Legacy 3DG
Note 1: Factory test mode is for manufacturing convenience. Support of this mode and device behavior in
this mode is up to the manufacturer.

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Note 2: Max allowable path loss from Legacy 3DD to Legacy 3DG. If the calculated path loss is greater
than this threshold, the Legacy 3DG will conclude that the Legacy 3DD in question is too distant and will
continue to search for a closer proximity Legacy 3DD.

Note 3: Legacy 3DGs incorrectly interpret the value of this field as an unsigned integer. In order to
maximize interoperability, a 3DD should set this field to a value between 0 and 127.

12.1.3 Reference Protocol Association Notification

The Legacy 3DD listens for a Reference Protocol Association Notification immediately
after sending the EIR. After selecting the Legacy 3DD, the Legacy 3DG performs an
inquiry and waits for an EIR from the selected Legacy 3DD. The Legacy 3DG
recognizes the selected Legacy 3DD based only on the BD_ADDR of the Legacy 3DD.
The Legacy 3DG then sends the Reference Protocol Association Notification message.
The Legacy 3DD sends an Ack to acknowledge the Reference Protocol Association
Notification message with a NULL packet as specified by Table 12.3. Once the Ack is
received, the Reference Protocol Association Notification is complete. Typically, upon
successful Reference Protocol Association Notification, a visual confirmation on the
Legacy 3DD would be displayed to the user.
If the Legacy 3DG does not receive the Ack, it continues the inquiry procedure and
attempts to deliver the message if it receives another inquiry response from the targeted
Legacy 3DD. If the inquiry times out, the Legacy 3DG repeats the inquiry and
association notification procedure a configurable number of times before giving up.
Even if the Reference Protocol Association Notification fails, the Legacy 3DG unit
considers itself associated with the Legacy 3DD. The Legacy 3DD does not change
over-the-air behavior based on Legacy 3DG(s) associating or not.
The Reference Protocol Association Notification packet and Ack is transmitted using the
same channel as the EIR packet.
The Reference Protocol Association Notification packet should be transmitted with the
same output power as the associated ID packet.
The Reference Protocol Association Notification Ack packet should be transmitted with
the same output power as the EIR packet.
The Legacy 3DG sends the Reference Protocol Association Notification message in a
DM1 packet. The Reference Protocol Association Notification message is specified in
Table 12.4.
Packet Entity Field Value Notes Compatibility
Access Code Sync Word Derived from the Required by
Legacy 3DD LAP. Legacy 3DDs.
See Note 1
Packet Header LT_ADDR 1 Required by
(Whitening Disabled) Legacy 3DDs.
(Required by Legacy TYPE DM1 Required by
3DD) Legacy 3DDs.
FLOW 0 Ignored by
Legacy 3DDs.
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Packet Entity Field Value Notes Compatibility

ARQN 0 Ignored by
Legacy 3DDs.
SEQN 0 Ignored by
Legacy 3DDs.
HEC Derived from the Required by
Legacy 3DD UAP Legacy 3DDs.
Payload Payload LLID 2 Ignored by
(Whitening Header Legacy 3DDs.
Disabled) FLOW 0 Ignored by
Legacy 3DDs.
LENGTH 17 Required by
Legacy 3DDs.
Payload 6 bytes used by the Legacy BD_ADDR of Field is
Body 3DG for the 3DG BD Address Legacy 3DG required by
Legacy 3DDs
but the
contents can
be any value.
Device/Service Type 0 – 3DG UINT8 Required by
1-255 – Reserved Legacy 3DDs.
Reserved 0x00 10 Ignored by
Bytes Legacy 3DDs.
Table 12.4: Format of the Reference Protocol Association Notification Message from Legacy 3DG to
Legacy 3DD
Note 1: This can create potential timing issues with other slaves (primarily slaves in long sniff/park) on the
Legacy 3DD piconet as they might sync to this packet accidently. This requires a match of the hop
frequency (probability =1/79) and a timing alignment that depends on the sniff interval of the slave device.
Typically slaves would also look for a valid HEC which may match by accident as whitening is disabled on
this packet (probability=1/256). An LT_ADDR check may or may not be done (probability=1/8), which
would further reduce the possibility of this match.
The Reference Protocol Association Notification Ack is specified in Table 12.5.
Packet Entity Field Value Notes Compatibility
Access Code Sync Word Derived from the Required by
Legacy 3DD LAP Legacy 3DGs.
Packet Header LT_ADDR 1 Required by
(Whitening Disabled) Legacy 3DGs.
TYPE NULL Ignored by
Legacy 3DGs.
FLOW 0 Ignored by
Legacy 3DGs.
ARQN 1 Required by
Legacy 3DGs.
SEQN 0 Ignored by
Legacy 3DGs.
HEC Derived from the Required by
Legacy 3DD UAP Legacy 3DGs.

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Table 12.5: Format of the Reference Protocol Association Notification Ack from Legacy 3DD to Legacy
3DG
12.1.4 Reference Protocol Association Notification Packet Timing
In a standard Bluetooth inquiry procedure, the slave snaps its clock phase to match the
master’s clock when the slave receives an ID packet from the master. This allows the
slave to transmit an FHS packet and an EIR packet at fixed delays from when it
received the ID packet. However, the slave cannot determine if it received the ID packet
in the first or the second half slot of the inquiry. Therefore, the Legacy 3DD cannot
determine when to listen for the Reference Protocol Association Notification packet and
so it is up to the Legacy 3DG to transmit the Reference Protocol Association Notification
packet at a time that makes reception of the packet equally probable from the
perspective of the 3DD.
The Reference Protocol Association Notification packet is transmitted in the 2nd slot
after the reception of the EIR as specified in Figure 12.2 and Figure 12.3 below and
section 12.1.4.3.

12.1.4.1 First Half Slot

Association
Notification
Master ID ID DM1
(3DG)

Slave FHS EIR NULL

(3DD)

Ack

Tanr

Figure 12.2: First half slot timing (single slot EIR shown)

12.1.4.2 Second Half Slot

Association
Notification

Master
ID ID DM1
(3DG)

Slave
FHS EIR NULL
(3DD)

Ack

Tanr

Figure 12.3: Second half slot timing (single slot EIR shown)

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12.1.4.3 Timing Offset from EIR

The parameter Tanr (Association Notification Response Time) is defined as the timing
offset from the start of the EIR packet to the start of the Reference Protocol Association
Notification packet and depends on the EIR packet type. The Tanr depends on the EIR
packet type, the length of the packet, and the role of the device.
Table 12.6 and Table 12.7 provide the combinations of Tanr values for different packet
types/lengths used by Legacy 3DDs and Legacy 3DGs to receive/transmit Reference
Protocol Association Notification. These tables should be referenced and used to
maximize interoperability of Legacy Association Notification transmission and reception
between a 3DD and 3DG.
EIR Packet Length Packet 3DD Tanr (Receive) 3DG Tanr (Transmit) Association
(Bytes) Type (ms) (ms) Notification
Interoperability
0x09-0x11 DM1 1.5625 1.5625 High
0x11-0x1b DM3 1.5625 1.5625 High
0x1c DM3 1.5625 1.5625 Low
0x1d-0x4e DM3 1.5625 1.5625 High
0x4f-0x51 DM3 1.5625 1.5625 Low
0x52-0x56 DM3 1.5625 2.8125 Low
0x57-0x6d DM3 2.8125 2.8125 Low
0x6e-0x79 DM3 2.8125 2.8125 High
Table 12.6: Tanr Values for DMx Packets
Association
EIR Packet Length Packet 3DD Tanr (Receive) 3DG Tanr (Transmit)
Notification
(Bytes) Type (ms) (ms)
Interoperability
0x0b-0x1b DH1 1.5625 1.5625 High
0x1c DH3 1.5625 1.5625 Low
0x1d-0x36 DH3 1.5625 1.5625 High
0x37 DH3 1.5625 1.5625 Low
0x38-0x51 DH3 1.5625 1.5625 High
0x52 DH3 1.5625 1.5625 Low
0x53-0x59 DH3 1.5625 1.5625 High
0x5a-0x7d DH3 1.5625 1.5625 Low
0x7e-0x83 DH3 1.5625 2.8125 Low
0x84-0xb6 DH3 2.8125 2.8125 Low
Table 12.7: Tanr Values for DHx Packets
12.1.4.3.1 Recommendations for Timing Offsets from EIR for Bluetooth 3D Devices

The use of DM5 and DH5 packets on 3DD for EIR is not recommended.
Some of the packet type/length combinations listed in the tables above have different
Tanr values for 3DD reception and for 3DG transmission of Legacy Association
Notification. To maximize interoperability, it is recommended that 3DD implementations
use the Tanr value that is recommended for the 3DG for a given EIR packet type/length,
and 3DG implementations use the Tanr value that is recommended for the 3DG for a
given EIR packet length/type.

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To maximize interoperability, the 3DD should preferably use DMx packet types instead
of DHx packet types. This can be configured at the HCI level by setting the
FEC_Required parameter to “FEC required” in the
HCI_Write_Extended_Inquiry_Response command.
To further improve interoperability, it is recommended that 3DD limit their EIR length
and packet types to one of the combinations listed in Table 12.8.
EIR Packet Length (Bytes) Packet Type
0x0a-0x11 DM1
0x11-0x1b DM3
0x1d-0x4e DM3
0x6e-0x79 DM3
Table 12.8: Recommended 3DD EIR Packet Lengths and Types
The EIR length 0x1c should be avoided. Note: BR/EDR Controllers may truncate any
octets of 0x00 at the end of an EIR packet, which may cause a longer packet to contain
a length field shorter than what was provided by the Host.

12.2 Synchronization Establishment

This section describes how the Legacy 3DG obtains initial sync to the 3D beacon from
the Legacy 3DD.
12.2.1 Top Level Sequence Diagram
The top level sequence diagram Figure 12.4 shows the sequence of actions used by a
Legacy 3DG to synchronize to the Legacy 3D beacon.

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Legacy 3DD Legacy 3DG

Listen for sync train from

Legacy 3DD

If sync train not found, page

the Legacy 3DD

Page (aborted)

Start Sync Train

Sync Train Listen for sync train

Legacy 3DG Synchronized

Beacon

Figure 12.4: Synchronization Procedure

1. The Legacy 3DG starts by listening for the synchronization train from the Legacy
3DD. The synchronization train is a periodic sequence of packets generated in
the controller and sent by the Legacy 3DD.
2. If the synchronization train is not found, the Legacy 3DG will page the Legacy
3DD but abort the connection. This acts as a trigger to the 3DD to start the
synchronization train.
3. The Legacy 3DG listens again for the synchronization train. This train has all the
necessary information for the Legacy 3DG to synchronize to and receive the 3D
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beacon from the Legacy 3DD. The 3D beacon contains the synchronization
information packets periodically generated by the Legacy 3DD host and
broadcast by the Legacy 3DD controller.
4. Legacy 3DG are now synchronized to the Legacy 3DD’s 3D beacon.
The following sections specify how the page sequence is aborted to trigger the
synchronization train. In both cases, the synchronization train shall be triggered when
no FHS packet is received for the number of slots defined in the baseband timer,
pagerespTO.

12.2.1.1 First Half Slot Sync Train Trigger

Standard part of the Aborted part of the

paging sequence paging sequence

Master ID ID FHS
(3DG)
FHS never
sent
Slave ID
(3DD)

Figure 12.5: First half slot sync train trigger timing

12.2.1.2 Second Half Slot Sync Train Trigger

Standard part of the Aborted part of the

paging sequence paging sequence

Master ID ID FHS
(3DG)
FHS never
sent
Slave
ID
(3DD)

Figure 12.6: Second half slot sync train trigger timing

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12.2.2 Synchronization Train

The synchronization train is a periodic sequence of DM3 packets sent on specific
frequencies. Figure 12.7 below illustrates an example of the synchronization train
timing.

Sync Train Channel 2402 Channel 2426 Channel 2480

Linkless
Broadcast

Tsync_packet_period
Tsync_train_period

Figure 12.7: Synchronization train frequency and timing example.

Tsync_train_period, the period between sync train instants, is 80 ms. Three packets are
transmitted at every Sync Train instant, with the first on channel 2402, second on
channel 2426, and third on channel 2480. The use of three channels is for redundancy.
As long as reception on one of the channels is successful, the system will work.
Tsync_packet_period is defined as the time from the start of a sync train packet to the start of
the next sync train packet in the same sync train instant. In the Reference Protocol,
Tsync_packet_period = 1 slot pair. But Tsync_packet_period = 1 slot pair is not required to be
backward compatible. To be backward compatible, Tsync_packet_period is limited only by the
requirement that the Legacy 3DD shall send 3 sync train packets every Tsync_train_period. It
is recommended that on any single channel, the sync train packet is sent at a periodic
interval of Tsync_train_period.
Legacy 3DG products scan for the sync train by receiving continuously on each channel
for 103.75 ms. Each channel is scanned in turn until the sync train is detected or a
timeout defined by the host application is reached. The timeout for Legacy 3DG varies
and is in the range of 1-5 seconds depending on the Legacy 3DG model. Legacy 3DG
scan for the sync train as follows:
1. Start timeout timer
2. Scan 3 frequencies for 103.75 ms each
3. If sync message is received,
1. Stop timeout timer
2. proceed to synchronized operation (beacon reception)
4. Else, (no sync message is detected),
a) Trigger sync train by paging (continue until ID received or timeout)
b) If ID received,
i. Then Scan for sync train until resync or timeout
ii. If sync message received,
1. Stop timeout timer
2. proceed to synchronized operation
c) Else, (timeout expires),
i. Enter low power mode

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Table 12.9 and Table 12.10 provide the parameters of the reconnect train and its
format. All packet fields are transmitted least significant byte first. All bytes are
transmitted least significant bit first.

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Train Parameter Values Comments Compatibility

Frequencies 2402, 2426, One DM3 per frequency Legacy 3DGs only scan these 3
2480 per period sent in master frequencies.
slot
Tsync_train_period 80ms Legacy 3DDs use 80 ms.
Legacy 3DGs scan for 103.75
ms. Legacy 3D product
implementations should work
with sync train transmit periods
between 10- 100 ms.
Duration 120 seconds Train is only sent for a 120 seconds is not a
short interval to allow requirement. The duration
Legacy 3DG to sync. This depends only on use case,
minimizes RF power consumption
interference for other requirements, and required
devices probability of detection.
Table 12.9: Synchronization Train Parameters

Packet Entity Field Value Notes Compatibility

Access Code Sync Word Derived from the Required by Legacy
Legacy 3DD LAP 3DGs.
Packet Header LT_ADDR 0 Legacy 3DGs can
(Whitening Disabled) accept any
LT_ADDR.
TYPE DM3 Required by Legacy
3DGs.

Other packet types

will be dropped. See
Note 1.
FLOW 0 Legacy 3DGs can
accept 0 or 1.
ARQN 0 Legacy 3DGs can
accept 0 or 1.
SEQN 0 Legacy 3DGs can
accept 0 or 1.
HEC Derived from the Required by Legacy
Legacy 3DD UAP 3DGs.
Payload Payload LLID 2 Legacy 3DGs can
(Whitening Header accept any LLID.
Disabled) Ignored by Legacy
3DGs.
FLOW 0 Legacy 3DGs can
accept 0 or 1.
LENGTH 28 Legacy 3DGs can
accept 28 to 121
byte packets.
Additional bytes
beyond 28 bytes are
ignored.

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Packet Entity Field Value Notes Compatibility

Payload Current clock Snapshot of bits 27:0 4 Bytes Required by Legacy
Body of the current Legacy 3DGs. Upper 4 bits
3DD Bluetooth clock of the 4-byte field
are not used
(masked out).
Next Beacon Bits 27:1 of the 4 Bytes Required by Legacy
clock Legacy 3DD 3DGs. Upper 5 bits
Bluetooth clock/2 at of the 4 bytes field
the next beacon shall be zero.
transmission (units of
slots)
AFH Channel AFH channel map 10 Bytes Required by Legacy
Map used for the beacon 3DGs. The format
transmissions used is as defined in
the LMP
specification. Bit 79
is set to zero by the
Legacy 3DD and
ignored by the
Legacy 3DG.
3DD BD Addr Legacy 3DD 6 Bytes Required by Legacy
BD_ADDR 3DGs.
Beacon In number of slots 2 Bytes, This field is required
Interval (current by Legacy 3DG but
products use values other than 80
128 slots = ms (e.g., 60-100 ms)
80 ms) should work.
Version 1 1 Byte Ignored by Legacy
3DGs.
Display ID 0: Home use UINT8 Some Legacy 3DGs
1: Cinema use use a value of 1 as a
2-255: Reserved for Cinema mode. LEDs
future use are typically
disabled in Cinema
mode. Some Legacy
3DGs also treat any
value greater than 0
as Cinema mode.
Table 12.10: Synchronization Train Message Format

12.3 3D Synchronized Operation

After the Legacy 3DG has established synchronization with the host controller 3D
beacon, it maintains sync by periodically listening to the beacon and adjusting its 3D
shutter timing based on the information in the beacons. Legacy 3DGs listen for the
beacon every 560 ms (7 times the Beacon Interval). If the Legacy 3DG fails to detect a
beacon at that time, then it listens every 80 ms (1 times the Beacon Interval). If the
Legacy 3DG fails again to detect the beacon, it will continue to listen for beacons with a
timeout of 5 seconds, after which it will return to a disconnect state. Subsequent
behavior of Legacy 3DG varies by model; some attempt to resynchronize immediately

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while others go into a low power state until the user initiates resynchronization (profile
behavior).

3DD 3DG

Beacon

Beacon

Beacon

Figure 12.8: 3D Synchronized Operation

12.3.1 Beacon Format

The beacon provides 3D timing information to the Legacy 3DG listening to it. It provides
the Frame Sync rising edge relative to the Legacy 3DD Bluetooth clock and shutter
control timing relative to Frame Sync (also relative to the Legacy 3DD Bluetooth clock).
All values in the following tables are in little-endian format.
Table 12.11 describes the contents of the Beacon Packet payload used by the
Reference Protocol. Any change to the contents of this profile should be specified at the
profile level.

Field Position Type Value Comments

Bluetooth clock at rising edge Byte 0 bit 0 to 0 to Bits[27:1] of the
of Frame Sync Byte 3 bit 2 2^27-1 Bluetooth Native
UINT32 clock. Byte 0 bit 0 =
Bit[1] of the Bluetooth
Native clock.

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Field Position Type Value Comments

Reserved Byte 3 bit 3 0 Set to 0 by
transmitter, expected
0 by receiver
Reserved Byte 3 bit 4 and 5 0 Set to 0 by
transmitter, ignored
by receiver.
Dual Video Stream Mode Byte 3 bit 6 0 or 1 0 – 3D mode

1 – Two image
stream mode. In this
mode left shutter
control signal should
be interpreted as
timing for video
stream 1 and Right
shutter control
information as timing
for video stream 2.
Reserved Byte 3 bit 7 0 Set to 0 by
transmitter, ignored
by receiver.
Bluetooth clock phase at rising Bytes 4,5 UINT16 0-624 Range 0-624
edge of Frame Sync (µs)
Left shutter open delay (µs) Bytes 6,7 UINT16 0-65535 Special value of
0xFFFF signals
(Video Stream 1 in dual Legacy 3DG to go
stream mode) into 2D mode.
Left shutter close delay (µs) Bytes 8,9 UINT16 0-65535

(Video Stream 1 in dual

stream mode)
Right shutter open delay (µs) Bytes 10,11 UINT16 0-65535

(Video Stream 2 in dual

stream mode)
Right shutter close delay (µs) Bytes 12,13 UINT16 0-65535

(Video Stream 2 in dual

stream mode)
Frame Sync Period (µs) Bytes 14,15 UINT16 0-40000
Frame Sync Fraction (1/256 Byte 16 UINT8 0-255
µs)
Table 12.11: Beacon Packet Payload Fields

Field Type/Size Comments Compatibility

Frequency Per the The transmit frequency for each packet Required by Legacy 3DGs.
adapted shall be chosen using master timing and
piconet clock. AFH may be used but AFH
connection information must be provided in the sync
state
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Field Type/Size Comments Compatibility

hopping train and cannot change after the
sequence. beacon has been started.
Table 12.12: Beacon Packet Parameters

Packet Entity Field Value Notes Compatibility

Access Code Sync Word Derived from the Required by
Legacy 3DD LAP Legacy 3DGs.
Packet Header LT_ADDR 1 An LT_ADDR of 1 Required by
(Whitening Enabled, must be reserved Legacy 3DGs.
based on Legacy 3DD by controllers that Legacy 3DGs will
clock bits [6:1]) support ignore any beacon
Connectionless packet with
Slave Broadcast LT_ADDR not
and used only for equal to 1.
Connectionless
Slave Broadcast.
TYPE DM1 Required by
Legacy 3DGs.

Any packet with a

type field not equal
to DM1 will be
ignored.
FLOW 0 Legacy 3DGs can
accept 0 or 1.
ARQN 0 Legacy 3DGs can
accept 0 or 1.
SEQN 0/1 Toggles per packet Toggled by Legacy
3DD, ignored by
Legacy 3DGs.
Legacy 3DGs can
accept 0 or 1.
HEC Derived from the Required for
Legacy 3DD UAP Legacy 3DGs.
Payload Payload LLID 2 Ignored by Legacy
(Whitening Header 3DGs. Legacy
Enabled, 3DGs can accept
based on any value.
Legacy FLOW 0 Legacy 3DGs can
3DD accept 0 or 1.
clock) LENGTH 17 Legacy 3DGs will
ignore packets that
are not 17 bytes.
Payload See Table 12.11: Beacon Packet Payload Fields
Body
Table 12.13: Beacon Packet Format

12.4 External Clock Capture and Generation

The objective of the 3D glasses is to open and close the left/right shutters to match
precisely the frame timing of the 3D display. To accomplish this objective, the
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Reference Protocol utilizes the ability inherent in all Bluetooth devices to align the slave
Bluetooth clock to the master Bluetooth clock. The slave only needs to know the state of
the master Bluetooth clock at the rising edge of the Frame Sync and the period of the
Frame Sync to accurately reproduce the Frame Sync signal at the slave.
The glasses don’t actually generate a Frame Sync signal directly. Instead, they use the
Frame Sync timing to generate Left/Right shutter signals as shown in Figure 12.9.

Figure 12.9: The Reference Protocol broadcasts synchronous clock signals over a wireless link.
The timing parameters include the following values:
1. Left Shutter Open Delay,
2. Left Shutter Close Delay,
3. Right Shutter Open Delay,
4. Left Shutter Close Delay.
These 4 timing parameters provide enough flexibility to implement several modes of
operation as illustrated in Figures 12.10, 12.11, and 12.12. Note that the timing
parameters sent by the display and the timing signal delays may be different. For
example,
Left Shutter Rising Edge Delay = Left Shutter Open Delay + open_offset.
The offset may be positive or negative and is determined by the glasses manufacturer
to optimize the viewing experience given the response behavior of the optics in those
particular glasses.
The Frame Rate is the inverse of the Frame Sync Period. The Legacy 3DG and Legacy
3DD support a range of Frame Rates from 48 Hz to 120 Hz.

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Frame Sync Frame Sync Frame Sync

Instant Instant Instant
Frame Sync Period (Tfs)

Frame Sync Signal:

Open Closed Open Closed

Shutter Signal Left:

Left Shutter
Rising Edge
Delay

Left Shutter Falling

Edge Delay

Closed Open Closed Open

Shutter Signal Right:

Right Shutter Rising

Edge Delay

Right Shutter Falling Edge Delay

Figure 12.10: In 3D mode, the left and right lenses alternate in open/close states.

Frame Sync Signal:

Open Closed Open Closed

Shutter Signal Left:

View 1
Open Closed Open Closed
Shutter Signal Right:

Closed Open Closed Open

Shutter Signal Left:

View 2
Closed Open Closed Open
Shutter Signal Right:

Figure 12.11: In dual view mode, the left and right open at the same time, but alternate with a 2nd pair of
glasses to create view 1 and view 2.

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Frame Sync Signal:

Shutter Signal Left: Open

Shutter Signal Right: Open

Figure 12.12: In 2D mode, the shutters stay open continuously.

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