ESP8684-DevKitM
Overview
The ESP8684-DevKitM is an entry-level development board based on ESP8684-MINI-1, a general-purpose module with 1 MB/2 MB/4 MB SPI flash. This board integrates complete Wi-Fi and Bluetooth LE functions. For more information, check ESP8684-DevKitM User Guide [1]
Hardware
ESP32-C2 (ESP8684 core) is a low-cost, Wi-Fi 4 & Bluetooth 5 (LE) chip. Its unique design makes the chip smaller and yet more powerful than ESP8266. ESP32-C2 is built around a RISC-V 32-bit, single-core processor, with 272 KB of SRAM (16 KB dedicated to cache) and 576 KB of ROM. ESP32-C2 has been designed to target simple, high-volume, and low-data-rate IoT applications, such as smart plugs and smart light bulbs. ESP32-C2 offers easy and robust wireless connectivity, which makes it the go-to solution for developing simple, user-friendly and reliable smart-home devices. For more information, check ESP8684 Datasheet [2].
Features include the following:
32-bit core RISC-V microcontroller with a maximum clock speed of 120 MHz
2 MB or 4 MB in chip (ESP8684) or in package (ESP32-C2) flash
272 KB of internal RAM
802.11b/g/n
A Bluetooth LE subsystem that supports features of Bluetooth 5 and Bluetooth Mesh
Various peripherals:
14 programmable GPIOs
3 SPI
2 UART
1 I2C Master
LED PWM controller, with up to 6 channels
General DMA controller (GDMA)
1 12-bit SAR ADC, up to 5 channels
1 temperature sensor
1 54-bit general-purpose timer
2 watchdog timers
1 52-bit system timer
Cryptographic hardware acceleration (RNG, ECC, RSA, SHA-2, AES)
For detailed information check ESP8684 Technical Reference Manual [3].
Supported Features
Current Zephyr’s ESP8684-DevKitM board supports the following features:
Interface |
Controller |
Driver/Component |
|---|---|---|
UART |
on-chip |
serial port |
GPIO |
on-chip |
gpio |
PINMUX |
on-chip |
pinmux |
Watchdog |
on-chip |
watchdog |
TRNG |
on-chip |
entropy |
Timers |
on-chip |
counter |
Wi-Fi |
on-chip |
|
LEDC |
on-chip |
pwm |
SPI Master |
on-chip |
spi |
SPI DMA |
on-chip |
spi |
For a getting started user guide, please check ESP8684-DevKitM User Guide [1].
System requirements
Prerequisites
Espressif HAL requires WiFi and Bluetooth binary blobs in order work. Run the command below to retrieve those files.
west blobs fetch hal_espressif
Note
It is recommended running the command above after west update.
Building & Flashing
Simple boot
The board could be loaded using the single binary image, without 2nd stage bootloader. It is the default option when building the application without additional configuration.
Note
Simple boot does not provide any security features nor OTA updates.
MCUboot bootloader
User may choose to use MCUboot bootloader instead. In that case the bootloader must be built (and flashed) at least once.
There are two options to be used when building an application:
Sysbuild
Manual build
Note
User can select the MCUboot bootloader by adding the following line to the board default configuration file.
CONFIG_BOOTLOADER_MCUBOOT=y
Sysbuild
The sysbuild makes possible to build and flash all necessary images needed to bootstrap the board with the ESP32 SoC.
To build the sample application using sysbuild use the command:
west build -b esp8684_devkitm --sysbuild samples/hello_world
By default, the ESP32 sysbuild creates bootloader (MCUboot) and application images. But it can be configured to create other kind of images.
Build directory structure created by sysbuild is different from traditional Zephyr build. Output is structured by the domain subdirectories:
build/
├── hello_world
│ └── zephyr
│ ├── zephyr.elf
│ └── zephyr.bin
├── mcuboot
│ └── zephyr
│ ├── zephyr.elf
│ └── zephyr.bin
└── domains.yaml
Note
With --sysbuild option the bootloader will be re-build and re-flash
every time the pristine build is used.
For more information about the system build please read the Sysbuild (System build) documentation.
Manual build
During the development cycle, it is intended to build & flash as quickly possible. For that reason, images can be built one at a time using traditional build.
The instructions following are relevant for both manual build and sysbuild. The only difference is the structure of the build directory.
Note
Remember that bootloader (MCUboot) needs to be flash at least once.
Build and flash applications as usual (see Building an Application and Run an Application for more details).
# From the root of the zephyr repository
west build -b esp8684_devkitm samples/hello_world
The usual flash target will work with the esp8684_devkitm board
configuration. Here is an example for the Hello World
application.
# From the root of the zephyr repository
west build -b esp8684_devkitm samples/hello_world
west flash
Open the serial monitor using the following command:
west espressif monitor
After the board has automatically reset and booted, you should see the following message in the monitor:
***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx *****
Hello World! esp8684_devkitm
Debugging
As with much custom hardware, the ESP8684 modules require patches to OpenOCD that are not upstreamed yet. Espressif maintains their own fork of the project. The custom OpenOCD can be obtained at OpenOCD ESP32 [4].
The Zephyr SDK uses a bundled version of OpenOCD by default. You can overwrite that behavior by adding the
-DOPENOCD=<path/to/bin/openocd> -DOPENOCD_DEFAULT_PATH=<path/to/openocd/share/openocd/scripts>
parameter when building.
Here is an example for building the Hello World application.
# From the root of the zephyr repository
west build -b esp8684_devkitm samples/hello_world -- -DOPENOCD=<path/to/bin/openocd> -DOPENOCD_DEFAULT_PATH=<path/to/openocd/share/openocd/scripts>
west flash
You can debug an application in the usual way. Here is an example for the Hello World application.
# From the root of the zephyr repository
west build -b esp8684_devkitm samples/hello_world
west debug