ESPRESSIF ESP8684-WROOM-02C 2.4 GHz WiFi and Bluetooth 5 Module User Manual

October 30, 2023
ESPRESSIF

ESPRESSIF ESP8684-WROOM-02C 2.4 GHz WiFi and Bluetooth 5 Module

ESPRESSIF-ESP8684-WROOM-02C-2-4-GHz-WiFi-and-Bluetooth-5-Module-PRODUCT-
IMG

User Manual

2.4 GHz Wi-Fi (802.11 b/g/n) and Bluetooth® 5 module Built around the ESP8684 series of SoC, RISC-V single-core microprocessor 2 MB/4 MB flash in a chip package 14 GPIOs On-board PCB antenna.

Module Overview

Features

CPU and On-Chip Memory

  • ESP8684H2 or ESP8684H4 embedded, 32-bit RISC-V single-core processor, up to 120 MHz
  • 576 KB ROM
  • 272 KB SRAM (16 KB for cache)
  • SiP flash (see details in Table 1 ESP8684-WROOM-02C Ordering Information)
  • Access to Flash accelerated by a cache
  • Supports flash In-Circuit Programming (ICP)

Wi-Fi

  • IEEE 802.11 b/g/n-compliant
  • The center frequency range of operating channel:2412 ~ 2462 MHz
  • Supports 20 MHz bandwidth in a 2.4 GHz band
  • 1T1R mode with data rate up to 72.2 Mbps
  • Wi-Fi Multimedia (WMM)
  • TX/RX A-MPDU, TX/RX A-MSDU
  • Immediate Block ACK
  • Fragmentation and defragmentation
  • Transmit opportunity (TXOP)
  • Automatic Beacon monitoring (hardware TSF)
  • 3 × Virtual Wi-Fi interfaces
  • Simultaneous support for Infrastructure BSS in Station mode, SoftAP mode, Station + SoftAP

mode, and promiscuous mode
Note that when the ESP8684 series scans in Station mode, the SoftAP channel will change along with the Station channel.

Bluetooth®

  • Bluetooth LE: Bluetooth 5
  • Speed: 125 kbps, 500 kbps, 1 Mbps, 2 Mbps
  • Advertising extensions
  • Multiple advertisement sets
  • Channel selection algorithm #2
  • Internal co-existence mechanism between Wi-Fiand Bluetooth to share the same antenna

Peripherals

  • GPIO, SPI, UART, I2C, LED PWM controller, general DMA controller, temperature sensor, SAR ADC, timers, and watchdogs.

Integrated Components on Module

  • 26 MHz crystal oscillator

Antenna Options

  • On-board PCB antenna

Operating Conditions

  • Operating voltage/Power supply: 3.0 ~ 3.6 V
  • Operating ambient temperature: –40 ~ 85 °C

Description

  • ESP8684-WROOM-02C is a general-purpose Wi-Fi and Bluetooth LE module. The rich set of peripherals and high performance make this module an ideal choice for smart homes, industrial automation, health care, consumer electronics, etc.
  • ESP8684-WROOM-02C comes with an onboard PCB antenna. It can be mounted onto the surface of a PCB board.

Module Overview

The ordering information for ESP8684-WROOM-02C is as follows:

Table 1: ESP8684-WROOM-02C Ordering Information

Module| Ordering Code| Chip Embedded| SiP Flash| Module Dimensions

(mm)

---|---|---|---|---
ESP8684-WROOM-02C| ESP8684-WROOM-02C-N2| ESP8684H2| 2 MB| 20.0 × 18.0 × 3.2
ESP8684-WROOM-02C-N4| ESP8684H4| 4 MB

  • The ESP8684H2 chip and the ESP8684H4 chip fall into the same category, namely the ESP8684 chip series.
  • ESP8684 integrates a rich set of peripherals including UART, I2C, LED PWM controller, general DMA controller, temperature sensor, and SAR ADC.

Note
For more information on ESP8684, please refer to ESP8684 Series Datasheet.

Pin Definitions

Pin Layout

The pin diagram below shows the approximate location of pins on the module.

ESPRESSIF-ESP8684-WROOM-02C-2-4-GHz-WiFi-and-Bluetooth-5-Module-
FIG-1

Pin Description

  • The module has 19 pins. See pin definitions in Table 2.
  • For peripheral pin configurations, please refer to ESP8684 Series Datasheet.

Table 2: Pin Definitions

Name No. Type1 Function
3V3 1 P Power supply

EN

|

2

|

I

| High: on, enables the chip. Low: off, the chip powers off.

Note: Do not leave the CHIP_EN pin floating.

Name No. Type1 Function
IO4 3 I/O/T GPIO4, ADC1_CH4, FSPIHD, MTMS
IO5 4 I/O/T GPIO5, FSPIWP, MTDI
IO6 5 I/O/T GPIO6, FSPICLK, MTCK
IO7 6 I/O/T GPIO7, FSPID, MTDO
IO8 7 I/O/T GPIO8

This pin is internally pulled high.

IO9| 8| I/O/T| GPIO9
GND| 9| P| Ground
IO10| 10| I/O/T| GPIO10, FSPICS0
RDX| 11| I/O/T| GPIO19, U0RXD
TXD| 12| I/O/T| GPIO20, U0TXD
NC| 13| —| NC
IO18| 14| I/O/T| GPIO18
IO3| 15| I/O/T| GPIO3, ADC1_CH3
IO2| 16| I/O/T| GPIO2, ADC1_CH2, FSPIQ
IO1| 17| I/O/T| GPIO1, ADC1_CH1
IO0| 18| I/O/T| GPIO0, ADC1_CH0
GND| 19| P| Ground

  1. P: power supply; I: input; O: output; T: high impedance.

Get Started

What You Need

To develop applications for a module you need:

  • 1 x ESP8684-WROOM-02C
  • 1 x Espressif RF testing board
  • 1 x USB-to-Serial board
  • 1 x Micro-USB cable
  • 1 x PC running Linux

In this user guide, we take the Linux operating system as an example. For more information about the configuration of Windows and macOS, please refer to ESP- IDF Programming Guide.

Hardware Connection

  1. Solder the ESP8684-WROOM-02C module to the RF testing board as shown in Figure 2.ESPRESSIF-ESP8684-WROOM-02C-2-4-GHz-WiFi-and-Bluetooth-5-Module-FIG-2
  2. Connect the RF testing board to the USB-to-Serial board via TXD, RXD, and GND.
  3. Connect the USB-to-Serial board to the PC.
  4. Connect the RF testing board to the PC or a power adapter to enable a 5 V power supply, via the Micro-USB cable.
  5. During download, connect IO0 to GND via a jumper. Then, turn ”ON” the testing board.
  6. Download firmware into Flash. For details, see the sections below.
  7. After downloading, remove the jumper on IO0 and GND.
  8. Power up the RF testing board again. The module will switch to working mode. The chip will read programs from Flash upon initialization.

Note
IO0 is internal logic high. If IO0 is set to pull-up, the Boot mode is selected. If this pin is pull-down or left floating, the Download mode is selected. For more information on ESP8684-WROOM-02C, please refer to ESP8684 Series Datasheet.

Set up Development Environment
The Espressif IoT Development Framework (ESP-IDF for short) is a framework for developing applications based on the Espressif ESP32. Users can develop applications with ESP8684 in Windows/Linux/macOS based on ESP-IDF. Here we take the Linux operating system as an example.

Install Prerequisites

To compile with ESP-IDF you need to get the following packages:

  • CentOS 7 & 8:

    • sudo yum -y update && sudo yum install git wget flex bison gperf python3 python3- pip
      python3-setup tools cmake ninja-build cache dfu-util libusbx
  • Ubuntu and Debian:

    • sudo apt-get install git wget flex bison gperf python3 python3-pip python3- setup tools
    • cmake ninja-build cache libffi-dev libssl-dev dfu-util libusb-1.0-0
  • Arch:

    • sudo pacman -S –needed gcc git make flex bison gperf python-pip cmake ninja ccache
    • dfu-util libusb

Note

  • This guide uses the directory ~/esp on Linux as an installation folder for ESP-IDF.
  • Keep in mind that ESP-IDF does not support spaces in paths.

Get ESP-IDF
To build applications for the ESP8684-WROOM-02C module, you need the software libraries provided by Espressif inESP-IDF repository.
To get ESP-IDF, create an installation directory (~/esp) to download ESP-IDF to and clone the repository with ‘git clone’:

  1. mkdir -p ~/esp
  2. cd ~/esp
  3. git clone –recursive https://github.com/espressif/esp-idf.git.

ESP-IDF will be downloaded into ~/esp/esp-idf. Consult ESP-IDF Versions for information about which ESP-IDF version to use in a given situation.

Set up Tools
Aside from the ESP-IDF, you also need to install the tools used by ESP-IDF, such as the compiler, debugger, Python packages, etc. ESP-IDF provides a script named ’install. sh’ to help set up the tools in one go.

  1. cd ~/esp/esp-idf
  2. ./install.sh

Set up Environment Variables
The installed tools are not yet added to the PATH environment variable. To make the tools usable from the command line, some environment variables must be set. ESP-IDF provides another script ’export. sh’ which does that. In the terminal where you are going to use ESP-IDF, run:

  1. $HOME/esp/esp-idf/export.sh

Create Your First Project

Start a Project
Now you are ready to prepare your application for the ESP8684-WROOM-02C module. You can start with the get-started/hello_world project from the examples directory in ESP-IDF. Copy get-started/hello_world to ~/esp directory:

  1. cd ~/esp
  2. cp -r $IDF_PATH/examples/get-started/hello_world .

There is a range of example projects in the examples directory in ESP-IDF. You can copy any project in the same way as presented above and run it. It is also possible to build examples in place, without copying them first.

Connect Your Device
Now connect your module to the computer and check under what serial port the module is visible. Serial ports in Linux start with ‘/dev/tty’ in their names. Run the command below two times, first with the board unplugged, then with plugged in. The port which appears the second time is the one you need:

  1. ls /dev/tty*

Note
Keep the port name handy as you will need it in the next steps.

Configure
Navigate to your ‘hello_world’ directory from Step 3.4.1. Start a Project, set the ESP8684 chip as the target, and run the project configuration utility ‘menu config’.

  1. cd ~/esp/hello_world
  2. idf.py set-target esp8684
  3. idf.py menuconfig

Setting the target with ‘idf.py set-target ESP8684’ should be done once, after opening a new project. If the project contains some existing builds and configurations, they will be cleared and initialized. The target may be saved in the environment variable to skip this step at all. See Selecting the Target for additional information. If the previous steps have been done correctly, the following menu appears:

ESPRESSIF-ESP8684-WROOM-02C-2-4-GHz-WiFi-and-Bluetooth-5-Module-
FIG-3

You are using this menu to set up project-specific variables, e.g. Wi-Fi network name and password, the processor speed, etc. Setting up the project with menu config may be skipped for “hello_word”. This example will run with the default configuration. The colors of the menu could be different in your terminal. You can change the appearance with the option ‘–style’. Please run ‘idf.py menu config –help for further information.

Build the Project
Build the project by running:

  1. idf.py build

This command will compile the application and all ESP-IDF components, then it will generate the bootloader, partition table, and application binaries.

  1. $ idf.py build
  2. Running CMake in directory /path/to/hello_world/build
  3. Executing ”cmake -G Ninja –warn-uninitialized /path/to/hello_world”…
  4. Warn about uninitialized values.
  5. — Found Git: /usr/bin/git (found version ”2.17.0”)
  6. — Building empty aws_iot component due to configuration
  7. — Component names: …
  8. — Component paths: …
  9. … (more lines of build system output)
  10. [527/527] Generating hello_world.bin
  11. esptool.py v2.3.1
  12. Project build complete. To flash, run this command:
  13. ../../../components/esptool_py/esptool/esptool.py -p (PORT) -b 921600
  14. write_flash –flash_mode dio –flash_size detect –flash_freq 40m
  15. 0x10000 build/hello_world.bin build 0x1000 build/bootloader/bootloader.bin 0x8000
  16. build/partition_table/partition-table.bin
  17. or run ’idf.py -p PORT flash’

If there are no errors, the build will finish by generating the firmware binary .bin file.

Flash onto the Device
Flash the binaries that you just built onto your module by running:

  1. idf.py -p PORT [-b BAUD] flash
  • Replace PORT with your ESP8684 board’s serial port name from Step: Connect Your Device.
  • You can also change the flash baud rate by replacing BAUD with the baud rate you need. The default baud rateis 460800.
  • For more information on idf.py arguments, see idf.py.

Note
The option ‘flash‘ automatically builds and flashes the project, so running ‘idf.py build‘ is not necessary

When flashing, you will see the output log similar to the following:

  1. esptool.py esp8684 -p /dev/ttyUSB0 -b 460800 –before=default_reset –after=hard_reset
  2. write_flash –flash_mode dio –flash_freq 80m –flash_size 2MB 0x0 bootloader/bootloader.bin
  3. 0x10000 hello_world.bin 0x8000 partition_table/partition-table.bin
  4. esptool.py v3.2-dev
  5. Serial port /dev/ttyUSB0
  6. Connecting…
  7. Chip is ESP8684
  8. Features: WiFi, BLE
  9. Crystal is 40MHz
  10. MAC: 7c:df:a1:e0:00:64
  11. Uploading stub…
  12. Running stub…
  13. Stub running…
  14. Changing the baud rate to 460800
  15. Changed.
  16. Configuring flash size…
  17. Flash will be erased from 0x00000000 to 0x00004fff…
  18. Flash will be erased from 0x00010000 to 0x00039fff…
  19. Flash will be erased from 0x00008000 to 0x00008fff…
  20. Compressed 18896 bytes to 11758…
  21. Writing at 0x00000000… (100 %)
  22. Wrote 18896 bytes (11758 compressed) at 0x00000000 in 0.5 seconds (effective 279.9 kbit/s)…
  23. The hash of the data was verified.
  24. Compressed 168208 bytes to 88178…
  25. Writing at 0x00010000… (16 %)
  26. Writing at 0x0001a80f… (33 %)
  27. Writing at 0x000201f1… (50 %)
  28. Writing at 0x00025dcf… (66 %)
  29. Writing at 0x0002d0be… (83 %)
  30. Writing at 0x00036c07… (100 %)
  31. Wrote 168208 bytes (88178 compressed) at 0x00010000 in 2.4 seconds (effective 569.2 kbit/s)…
  32. The hash of the data was verified.
  33. Compressed 3072 bytes to 103…
  34. Writing at 0x00008000… (100 %)
  35. Wrote 3072 bytes (103 compressed) at 0x00008000 in 0.1 seconds (effective 478.9 kbit/s)…
  36. The hash of the data was verified.
  37. Leaving…
  38. Hard resetting via RTS pin…
  39. Done

If there are no issues by the end of the flash process, the board will reboot and start up the “hello_world” application.

Monitor

To check if “hello_world” is indeed running, type ‘idf.py -p PORT monitor‘ (Do not forget to replace PORT withyour serial port name). This command launches the IDF Monitor application:

  1. $ idf.py -p /dev/ttyUSB0 monitor
  2. Running idf_monitor in directory […]/esp/hello_world/build
  3. Executing ”python […]/esp-idf/tools/idf_monitor.py -b 115200
  4. […]/esp/hello_world/build/hello-world.elf”…
  5. — idf_monitor on /dev/ttyUSB0 115200 —
  6. — Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H —
  7. ETS Jun 8, 2016, 00:22:57
  8. rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
  9. ETS Jun 8, 2016, 00:22:57

After startup and diagnostic logs scroll up, you should see “Hello world!” printed out by the application.

  1. Hello, world!
  2. Restarting in 10 seconds…
  3. This is esp8684 chip with 1 CPU core(s), This is esp8684 chip with 1 CPU core(s), WiFi/BLE,
  4. silicon revision 0, 2MB external flash
  5. Minimum free heap size: 390684 bytes
  6. Restarting in 9 seconds…
  7. Restarting in 8 seconds…
  8. Restarting in 7 seconds…

To exit the IDF monitor use the shortcut Ctrl+]. That’s all that you need to get started with the ESP8684-WROOM-02C module! Now you are ready to try some other examples in ESP-IDF or go right to develop your own applications.

U.S. FCC Statement

The device complies with KDB 996369 D03 OEM Manual v01. Below are integration instructions for host product manufacturers according to the KDB 996369 D03 OEM Manual v01.

List of Applicable FCC Rules

  • FCC Part 15 Subpart C 15.247

Specific Operational Use Conditions
The module has WiFi and BLE functions.

  • Operation Frequency:
    • WiFi: 2412 ~ 2462 MHz
    • Bluetooth: 2402 ~ 2480 MHz
  • Number of Channels:
    • WiFi: 11
    • Bluetooth: 40
  • Modulation:
    • WiFi: DSSS; OFDM
    • Bluetooth: GFSK
  • Type: On-board PCB Antenna
  • Gain: 3.26 dBi Max

The module can be used for IoT applications with a maximum 3.26 dBi antenna. The host manufacturer installing this module into their product must ensure that the final composite product complies with the FCC requirements by a technical assessment or evaluation to the FCC rules, including the transmitter operation. The host manufacturer has to be aware not to provide information to the end user regarding how to install or remove this RF module in the user’s manual of the end product which integrates this module. The end user manual shall include all required regulatory information/warnings as shown in this manual.

Limited Module Procedures
Not applicable. The module is a single module and complies with the requirement of FCC Part 15.212.

Trace Antenna Designs
Not applicable. The module has its own antenna and does not need a host’s printed board microstrip trace antenna, etc.

RF Exposure Considerations
The module must be installed in the host equipment such that at least 20 cm is maintained between the antenna and the user’s body; and if the RF exposure statement or module layout is changed, then the host product manufacturer is required to take responsibility for the module through a change in FCC ID or new application. The FCC ID of the module cannot be used on the final product. In these circumstances, the host manufacturer will be responsible for re- evaluating the end product (including the transmitter) and obtaining a separate FCC authorization.

Antennas
Antenna specifications are as follows:

  • Type: PCB Antenna
  • Gain: 3.26 dBi

This device is intended only for host manufacturers under the following conditions:

  • The transmitter module may not be co-located with any other transmitter or antenna.
  • The module shall be only used with the external antenna(s) that has been originally tested and certified with this module.
  • The antenna must be either permanently attached or employ a ‘unique’ antenna coupler.

As long as the conditions above are met, further transmitter tests will not be required. However, the host manufacturer is still responsible for testing their end product for any additional compliance requirements required with this module installed (for example, digital device emissions, PC peripheral requirements, etc.).

Label and Compliance Information
Host product manufacturers need to provide a physical or e-label stating “Contains FCC ID:2AC7Z-ESP868402C” with their finished product.

Information on test modes and additional testing requirements

  • Operation Frequency:
    • WiFi: 2412 ~ 2462 MHz
    • Bluetooth: 2402 ~ 2480 MHz
  • Number of Channel:
    • WiFi: 11
    • Bluetooth: 40
  • Modulation:
    • WiFi: DSSS; OFDM
    • Bluetooth: GFSK

Host manufacturers must perform tests of radiated and conducted emission and spurious emission, etc., according to the actual test modes for a stand-alone modular transmitter in a host, as well as for multiple simultaneously transmitting modules or other transmitters in a host product. Only when all the test results of test modes comply with FCC requirements, then the end product can be sold legally.

Additional testing, Part 15 Subpart B compliant
The modular transmitter is only FCC authorized for FCC Part 15 Subpart C 15.247 and the host product the manufacturer is responsible for compliance to any other FCC rules that apply to the host not covered by the modular transmitter grant of certification. If the grantee markets their product as being Part 15 Subpart B compliant (when it also contains unintentional- radiator digital circuity), then the grantee shall provide a notice stating that the final host product still requires Part 15 Subpart B compliance testing with the modular transmitter installed. This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one of the following measures:

  • Reorient or relocate the receiving antenna.
  • Increase the separation between the equipment and the receiver.
  • Connect the equipment to an outlet on a circuit different from that to which the receiver is connected.
  • Consult the dealer or an experienced radio/TV technician for help.

This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:

  • This device may not cause harmful interference.
  • This device must accept any interference received, including interference that may cause undesired operation.

Caution
Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.

This equipment complies with FCC RF radiation exposure limits set forth for an uncontrolled environment. This device and its antenna must not be co-located or operating in conjunction with any other antenna or transmitter. The antennas used for this transmitter must be installed to provide a separation distance of at least 20 cm from all persons and must not be co-located or operating in conjunction with any other antenna or transmitter.

OEM Integration Instructions
This device is intended only for OEM integrators under the following conditions:

  • The transmitter module may not be co-located with any other transmitter or antenna.
  • The module shall be only used with the external antenna(s) that has been originally tested and certified with this module.

As long as the conditions above are met, further transmitter tests will not be required. However, the OEM integrator is still responsible for testing their end-product for any additional compliance requirements required with this module installed (for example, digital device emissions, PC peripheral requirements, etc.).

Validity of Using the Module Certification
In the event that these conditions cannot be met (for example certain laptop configurations or co-location with another transmitter), then the FCC authorization for this module in combination with the host equipment is no longer considered valid and the FCC ID of the module cannot be used on the final product. In these circumstances, the OEM integrator will be responsible for re-evaluating the end product (including the transmitter) and obtaining a separate FCC authorization.

End Product Labeling
The final end product must be labeled in a visible area with the following: “Contains Transmitter Module FCC ID:2AC7Z-ESP868402C”.

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Revision History

Date Version Release notes
2022-08-29 v0.5 For certification only

Disclaimer and Copyright Notice

Information in this document, including URL references, is subject to change without notice.
ALL THIRD-PARTY’S INFORMATION IN THIS DOCUMENT IS PROVIDED AS IS WITH NO WARRANTIES TO ITS AUTHENTICITY AND ACCURACY. NO WARRANTY IS PROVIDED TO THIS DOCUMENT FOR ITS MERCHANTABILITY, NONINFRINGEMENT, OR FITNESS FOR ANY PARTICULAR PURPOSE, NOR DOES ANY WARRANTY OTHERWISE ARISE OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE.
All liability, including liability for infringement of any proprietary rights, relating to the use of information in this document is disclaimed. No licenses express or implied, by estoppel or otherwise, to any intellectual property rights are granted herein. The Wi-Fi Alliance Member logo is a trademark of the Wi-Fi Alliance. The Bluetooth logo is a registered trademark of Bluetooth SIG. All trade names, trademarks, and registered trademarks mentioned in this document are the property of their respective owners and are hereby acknowledged.
Copyright © 2022 Espressif Systems (Shanghai) Co., Ltd. All rights reserved. www.espressif.com.

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