ESP Series of Products
FCC Certification Guide
Related products
ESP32 series
ESP32-S2 series
ESP32-S3 series
ESP32-C3 series
ESP32-C6 series
ESP32-H2 series
ESP8266 series
ESP8285 series
Version 1.0
Espressif Systems
Copyright © 2021
www.espressif.com
About This Document
This guide focuses on FCC certification tests for ESP series of products.
Release Notes
Date Version Release Notes
2021.08 v1.0 Initial release.
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Certification
Download certificates for Espressif products from
https://www.espressif.com/en/certificates.
Table of Contents
1. Test Preparation ........................................................................................................................... 1
1.1. Hardware Preparation ......................................................................................................... 1
1.2. Software Preparation........................................................................................................... 1
1.3. Download the Test Bin ........................................................................................................ 1
1.3.1. Setup Download Environment ................................................................................ 2
1.3.2. Download Test Bin ................................................................................................. 2
2. Fixed Frequency Test................................................................................................................... 6
2.1. Environment Setup .............................................................................................................. 6
2.2. Run the Test Bin .................................................................................................................. 8
2.2.1. Wi-Fi Fixed Frequency Test .................................................................................... 8
2.2.2. Bluetooth Fixed Frequency Test ............................................................................. 9
3. FAQ............................................................................................................................................. 10
1. Test Preparation
1. Test Preparation
1.1. Hardware Preparation
Three hardware devices are needed for FCC certification tests: the DUT (device under
test), serial port board, and USB cable as shown in Table 1-1.
Table 1-1. Hardware Description
Item Picture Quantity Description
Products designed based on ESP
DUT N/A 6
chips or modules
Connect the PC with the Dupont
Serial port cables from the DUT. It serves as the
1
board USB-UART converter that allows the
PC to communicate with the DUT.
Connect PC with the serial port
USB cable 1
board.
Note:
It is recommended to buy Espressif’s serial port board via this link to reduce testing interference and
to your convenience.
1.2. Software Preparation
Download the software required for FCC certification. Table 1-2 is the software
description.
Table 1-2. Software Description
Item Description
ft232r-usb-uart.zip The driver application for Espressif’s serial port board.
It contains the test bin files and tools for downloading
ESP_RF_test_tool.zip
and running the bin.
1.3. Download the Test Bin
Before you conduct any test, please set up the download environment and then
download the test bin according to this section.
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1. Test Preparation
1.3.1. Setup Download Environment
Table 1-3. Setup Download Environment
Chip Description
• Connect 3V3/CH_EN pins to the 3.3 V power supply
• Connect RXD/TXD/GND pins to corresponding pins of a serial
ESP8266 converter so that PC can communicate with DUT
ESP8285 • Pull MTDO (GPIO15) low
• Pull GPIO0 (Boot) low to make DUT enter the downloading
mode
• Connect 3V3/CH_EN pins to the 3.3 V power supply
ESP32 • Connect RXD/TXD/GND pins to corresponding pins of a serial
ESP32-S2 converter so that PC can communicate with DUT
ESP32-S3 • Pull GPIO0 (Boot) low to make DUT enter the downloading
mode
• Connect 3V3/CH_EN pins to the 3.3 V power supply
ESP32-C3 • Connect RXD/TXD/GND pins to corresponding pins of a serial
ESP32-C6 converter so that PC can communicate with DUT
ESP32-H2 • Pull GPIO9 (Boot) low and GPIO8 high to make DUT enter the
downloading mode
1.3.2. Download Test Bin
After building the hardware environment, please download the test bin as follows:
1. Switch on the serial port board, and the indicator LED will light up as shown in
Figure 1-1.
USB
Power Switch TX and RX
3V3 and GND
Figure 1-1. Connection with Serial Port Board
2. Unzip and open EspRFTestTool.
• Select the ChipType, COM, BaudRate, and click on Open to open the serial port.
• Select Flash as the download address.
• Select the test bin for your chip (see Table 1-4)
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1. Test Preparation
Table 1-4. Non-signaling RF Test Bin and the Download Address
Non-signaling RF Test Bin Chip Feature
Chip
Download Wi-Fi Bluetooth
Bin Address
Bluetooth
11b, 11g, 11n-HT20, 11n- &
ESP32 ESP32_RFTest_Bin 0x1000
HT40 Bluetooth
LE 4.2
11b, 11g, 11n-HT20, 11n-
ESP32-S2 ESP32-S2_RFTest_Bin 0x1000 —
HT40
11b, 11g, 11n-HT20, 11n-
ESP32-S3 ESP32-S3_RFTest_Bin 0x0 BLE 5.0
HT40
11b, 11g, 11n-HT20, 11n-
ESP32-C3 ESP32-C3_RFTest_Bin 0x0 BLE 5.0
HT40
11b, 11g, 11n-HT20, 11n-
ESP32-C6 ESP32-C6_RFTest_Bin 0x0 BLE 5.0
HT40
BLE 5.2 &
ESP32-H2 ESP32-H2_RFTest_Bin 0x0 — Zigbee &
Thread
ESP8266
ESP8266_RFTest_Bin 0x0 11b, 11g, 11n-HT20 —
ESP8285
• Click on the Load bin button and SUCC will show once the download succeeds.
Figure 1-2 shows the interface of downloading test bin for ESP32
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1. Test Preparation
Figure 1-2. Download Test Bin for ESP32
EspRFTestTool's default download address is 0x1000, so it is only applicable to ESP32
and ESP32-S2. For chips with a download address of 0x0, please use DownloadTool.
Figure 1-3 shows the interface of downloading ESP32-C3 test bin with this tool. For
more details on how to use DownloadTool, please refer to DownloadTool Instructions
under the help folder.
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1. Test Preparation
Figure 1-3. Download Test Bin for ESP32-C3
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2. Fixed Frequency Test
2. Fixed Frequency Test
This chapter describes how to run the fixed frequency test bin on the products that are
based on ESP chips or modules.
2.1. Environment Setup
In hardware, the EN pin of ESP chips is usually designed to be connected to the 3V3
power line via an RC delay circuit. Solder Dupont wires to the TXD0, RXD0, Boot, 3V3,
and GND of the chip and connect them to the corresponding pins of the serial port
board. Connect the serial port board to the PC with a USB cable so that the PC can
communicate with the DUT and power up the serial port board. Figure 2-1 shows a
block diagram that illustrates the test environment setup for the DUT.
Figure 2-1. Environment Setup Block Diagram
When testing conduction, RF cable is attached to the back of the ESP RF matching,
and if an antenna is also attached to the back of the Π match, it should be
disconnected. When RF matching is included within a module shield, the RF cable
should be soldered to the outside the shield, as shown in Figure 2-2.
When testing radiation, connect the antenna directly to the back of the RF matching
and ensure that it has no obstruction around.
Figure 2-2. RF Cable Connection for Module Conduction Test
Table 2-1 lists the hardware environment for each chip to run the test bin, which is
slightly different from the environment to download the bin (differences marked in
boldface).
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2. Fixed Frequency Test
Table 2-1. Hardware Setup for Running the Test Bin
Chip Description
• Connect 3V3/CH_EN pins to the 3.3 V power supply
• Connect RXD/TXD/GND pins to corresponding pins of a serial
ESP8266
converter so that PC can communicate with DUT
ESP8285
• Pull MTDO (GPIO15) low
• Pull GPIO0 high
• Connect 3V3/CH_EN pins to the 3.3 V power supply
ESP32
• Connect RXD/TXD/GND pins to corresponding pins of a serial
ESP32-S2
converter so that PC can communicate with DUT
ESP32-S3
• Pull GPIO0 high
• Connect 3V3/CH_EN pins to the 3.3 V power supply
ESP32-C3
• Connect RXD/TXD/GND pins to corresponding pins of a serial
ESP32-C6
converter so that PC can communicate with DUT
ESP32-H2
• Pull both GPIO9 and GPIO8 high
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2. Fixed Frequency Test
2.2. Run the Test Bin
2.2.1. Wi-Fi Fixed Frequency Test
• Disconnect IO0 of the DUT, and then toggle the power switch of the serial port
board to power it up.
• In EspRFTestTool, click on WiFi Test, and select TX continues as the Test Mode.
• You can decrease power by setting values in the field of Attenuation(0.25dB).
The unit is 0.25 dB, which means the value 20 represents a decrease of the
maximum power by 20x0.25=5dB. The field defaults to 0, meaning no
attenuation.
• Select other options according to the laboratory test needs. Then click on start to
start the fixed frequency test. The log is displayed in the tool. Figure 2-3 shows
the test interface of ESP32.
Figure 2-3. ESP32 Wi-Fi Fixed Frequency Test
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2. Fixed Frequency Test
2.2.2. Bluetooth Fixed Frequency Test
The bin for Bluetooth Fixed Frequency tests is the same as that for Wi-Fi.
• Open EspRFTestTool, and select the ChipType of the DUT. The ESP8266,
ESP32-S2 series of chips do not have Bluetooth functionality, so there is no
Bluetooth test for them. ESP32-C3 series of chips only support Bluetooth LE.
• Switch to the BT Test tab and configure the parameters: In general, set Power
Level to 4 and other parameters according to the actual needs. Figure 2-4 shows
the ESP32 Bluetooth Fixed Frequency Test interface.
Figure 2-4. Bluetooth Test Interface
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3. FAQ
3. FAQ
Q: How do I update the power parameters of a certification test to the application
firmware?
A: Please refer to the ESP32-Series_PowerLimitTool_Instructions_EN documentation.
Q: The second, third, and fourth harmonics of fixed frequency test radiation exceed the
standard.
A: 1. For ESP chip-based products, please check the RF layout, matching, and PA
power supply. You can suppress harmonics by adjusting the RF matching and PA
power line filtering network.
2. For ESP module-based products, place the backplane under the module, which is
usually the PCB board of the product.
3. Enter a value in the attenuation field of the fixed frequency test tool to reduce the
power.
Q: Band Edge and RE in Restricted Band exceed the standard.
A: 1. Make sure the RF matching is tuned correctly.
2. Enter a value in the attenuation field of the fixed frequency test tool to reduce the
power.
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