This is still a prototype, the circuit design was built and tested on a perfboard, the kicad board design was never tested. use at your risk and plz don't come whining if you damage stuff or set your house on fire.
This project entails working with a 220V powered device, with a metal chassis and no grounding. these devices are 40+ years old and saw lots of abuse, wires insulations may fail, motor windings may short circuit. before wiring anything up, check impedance between the chassis, the engine hull and all contacts carrying 220V power, anything below 2 megaohms means insulations need to be re-checked. Consider wiring the blind chassis to the ground line for additional safety
Arduino based driver board to control Acotral MA100 electric locootives front and side stops blinds.
Acotral MA100s were first issued to Rome's "A" metro line were they were in service between 1980 and 2005, before being overhauled/modified and reassigned to Roma Lido line until their decommissioning in 2018.
Stops signaling blinds coming from wagons dismantling started circuilating among flip clocks collectors and have become a somewhat commong find on online markets
Blinds are controlled through 7 bits string identifying stops and are powered at 110V AC (motor)/ 48V DC (control), this project emulates original locomotive control signals to drive them and display stops.
The board design in this project runs 5V DC control signals and 220V power, it requires minimal modifications to the original blinds wiring, it is fairly easy anyhow to adapt it to run 48V/110V to 100% preserve the integrity of original wiring.
- Runs through stops using the blidn's internal motor
- Allows manual stop selection or programmed stops sequence mode
- Allows to save configurations to the Arduino EEprom
- Implements several controls prevent damage/overheating in case of malfunctions
In manual mode (default) stops are selected thorugh serial port commands, or single button presses. The board led is lit during Manual mode.
Program mode automatically loops a sequence of stops, one step every hour by default. the program will be resumed from the last reached stop in case of power OFF/ON, hourly step timer will be reset. The board led is off during Program mode.
To switch between modes, either use serial commands or press the board button for 3 seconds.
- EEPROM (comes with Arduino IDE)
- Rocket Scream Low Power
check the schematic in this repo, I've built and tested it on perfboard, board design might not be 100% correct, and definitely the layout could use some improvement.
How to read led signals
Either for good or bad news, Arduino board led will flash.
A punched roller is used to encode 40 unique blind position, when a string of bits is applied to the pinstripe the motor spins until the holes combination under the pinstripe matches powered pins, i.e.:
- 0b00111000 bit string corresponding to Termini station is appled to the pinstripe, powering pins 4,5,6 from the left (1st left pin is common)
- 0b0011110 bit string on the control roller is under the pinstripe, current flows through pins 4,5,6, the motor spins
- Next roller bit string is 0b0100110 string on the control roller is under the pinstripe, current flows through pins 6, the motor keeps spinning
- The roller bit string is now 0b11000111, all 1s on the pinstripe match a 0 on the roller, no currnt flows, the motor stops and wil remain stil until a different bit string is selected.
The original control board has 7 control pins, 2 relais coil pins and 2 motor power pins, exposed through a DIN 41622 male connector on the side or back or back panel
The original wiring:
- Pin 1-6 and 12: stop selection bit string
- Pin 11: unwired
- Pin 10: 110V AC to relais terrupted line
- Pin 9: Relais coil ( +48V signal from selection roller return line)
- Pin 8: Relais coil N
- Pin 7: 110V returning from motor
the blind board schematic is available in "metroBlindDriver blind board" Kicad design:
In the original blind design, 48V DC bits would be fed in pins 1-6 and 12, they would reach the control roller throudh diodes and would power the 48V relays coil through the roller common pin, until the desired stop was reached.
The original blind wiring can be easily modificed to accept standard household 220V AC power and 5V DC signals,
IMPORTANT: don't use this board design with 48V signals to avoid damage and fire hazard!
IMPORTANT: don't run 220V AC through the motor before its coils are wired in series to avoid damage and fire hazard!
220V AC motor wiring
Wire the motor as shown in the picture below to drive it with 220V AC power, plastic motor caps on most (all?) blinds have diagrams explaining how to wire coils in series/parallel
5V DC external relais wiring
To bypass the 48V coil and use an external relais, clip the motor N wire from the connector board trace (board end, not motor end!) and solder it to the top left pin on the DIN connector, if in doubt, use the only pin trace with no wires attached.
Replacing the original 48V relais with a 5V or 12V one isn't sufficient, as the coil has a 4kohm resistor wired in series, plus, compatible relais are out of production, hard to source and quite expensive.
I wanted to preserve the original circuitry as much as possible, but definitely didn't want to faff with 48V signals. I figured since I had already wired the motor for 220V AC another small modification wouldn't matter much, and moving a wire to a diffeent pin seemed way less invasive than replacing a relais and a big *ss resitor. You might want to do things differently here, the circuit is easy enough to work with, these are just my2c :-)
Rewired schematic below:
The new wiring:
- Pin 1-6 and 12: 5V bit string
- Pin 11: to motor relais NO contact on Arduino board
- Pin 10: unwired, can be used to ground the blind chassis
- Pin 9: to Arduino "Any Running" pin
- Pin 8: unwired
- Pin 7: to motor relais NO contact on Arduino board
First things first, let's not fry stuff
- Check wirings and tensions
- Mandatory rewire the blind board to use and external 5V relais, don't use 48V signals with this Arduino board design!
- Optional rewire the motor to run on 220V AC, if you happen to have a 110V AC power source, that will work fine
- Wire the DIN connector pins, be sure not to short circuit anything
- Power the board and the motor L wire No smoke? good.
By Default the controller will wait for commands in manual mode with the board led ON
- Press the board button briefly, the blind should roll one stop forward
- (Optional) press the board button for 3 seconds to switch to Program mode
- Brief press: move one stop forward
- 3 seconds press: switch between Manual and Program mode
Commands format: (<<|>>)[A-Z,0-9]+
- << to read info, >> to set
- command name, in caps
- (where applicable) parameters
One command per line, the parser is pretty crude, pls stick to tested commands ;-)
Available commands:
- >>GO[0-9][0-9] select stop by zero padded two digits number, 1-40 (only works in manual mode)
- >>(stop name) (i.e. >>ANANGNINA, >>CINECITTA) select stop by name (only works in manual mode)
- >>STOP halt the motor
- >>RUN continuously run the motor
- >>PROGRAMSTEPSSECONDS[0-9]{4} write steps duration for program mode, zero padded four digits
- <<PROGRAMSTEPSSECONDS read steps duration for program mode
- >>DEFAULTPROGRAM load the default stops program to memory
- >>PROGRAMSTOPS[0-9]0-9{0,39} write program mode stops sequence, zero terminated, up to 40 zero padded two digits positive integers, the sequence is required to be ascending (i.e. 1-2-3 valid, 1-3-2 not valid)
- <<PROGRAMSTOPS print the program stops sequence currently in memory
- >>PROGRAMMODE switch to Program mode
- >>MANUALMODE switch to Manual mode (default)
- >>RESETDEFAULTS reset default configuration
- >>EEPROMDATA read current conf from eeprom
- <<EEPROMDATA write current conf to eeprom
- <<POSITION print the current blind roller position
- <<COMPILEDATETIME print the sketch build timestamp
-DEBUG_MODE enable serial port debug messages, disable sleep mode
The control roller pinstripe 8 signals encode 40 unique bit strings, each with three raised bits (i.e. 0b11001000, 0b00110010). This allows to move from any stop to any other applying the destination code bit string to stop selection pins.
At least, this is how the control roller would work hadn't its original designers decided to leave the rightmost pin unwired.
As a result, 5 out of 40 stops are encoded by only wired 2 pins and only work when selected starting from the 13 stops right behind them. the matrix below highlights misencoded stops and the stops that would be wrongly displayed when their code is used, i.e.
- The blind displays stop 2 (code 0b1000110)
- Stop 21 (code 0b1100000) is selected
- The blind spins until stop 6, (code 0b1100001)
- The bitwise "(input bit string) AND NOT (roller bit string)" of stops 21 and 6 codes is 0 -> the relais coil is not powered
- The blind stopped on stop 6 before reaching 21 and would halt on 26,27,30 and 37 due to the same reason
- (Note: code 0b1100000 correctly drives the blind to stop 21 starting form stops 7-20)
This behavior did not affect actual service on Roma Metro A as the 5 impacted stops were blank, I decided to leave it unchanged as an interesting quirk of the original design, you might want to fix it if you plan to display anything on stops 21-25 :-D
Q: I can't tell what's going on with eeprom data
A: <<EEPROMDATA command can extracts all the info saved on the eeprom
Q: I keep getting "unexistent stop" error
A: check wiring, any short circuit? any missing wire?
Q: Motor buzzeds and doesn't spin! what's wrong?
A: Have you rewired the motor correctly?
Q: I rebooted the board, and all my configurations are lost
A: Run >>EEPROMDATA to persist configuration on eeprom
Q: That PCB design is lame!
A: It is. any help much appreciated! ;-)
- Readme completion
- Circuit board layout improvement