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ESP32-C3 is a single-core Wi-Fi and Bluetooth 5 (LE) microcontroller SoC, based on the open-source RISC-V architecture. It strikes the right balance of power, I/O capabilities and security, thus offering the optimal cost-effective solution for connected devices. The availability of Wi-Fi and Bluetooth 5 (LE) connectivity not only makes the device configuration easy, but it also facilitates a variety of use-cases based on dual connectivity. 1

The features include the following:

  • 32-bit core RISC-V microcontroller with a maximum clock speed of 160 MHz

  • 400 KB of internal RAM

  • 802.11b/g/n/e/i

  • A Bluetooth LE subsystem that supports features of Bluetooth 5 and Bluetooth mesh

  • Various peripherals:

    • 12-bit ADC with up to 18 channels

    • TWAI compatible with CAN bus 2.0

    • Temperature sensor

    • 4x SPI

    • 2x I2S

    • 2x I2C

    • 3x UART

    • LED PWM with up to 16 channels

  • Cryptographic hardware acceleration (RNG, ECC, RSA, SHA-2, AES)

System requirements

Build Environment Setup

Some variables must be exported into the environment prior to building this port. Find more information at Setting Variables on how to keep this settings saved in you environment.


In case of manual toolchain installation, set ESPRESSIF_TOOLCHAIN_PATH accordingly. Otherwise, set toolchain path as below. If necessary.

On Linux and macOS:

export ESPRESSIF_TOOLCHAIN_PATH="${HOME}/.espressif/tools/riscv32-esp-elf/"

On Windows:

# on CMD:
set ESPRESSIF_TOOLCHAIN_PATH=%USERPROFILE%\.espressif\tools\riscv32-esp-elf\\riscv32-esp-elf

# on PowerShell
$env:Path += "$env:ESPRESSIF_TOOLCHAIN_PATH\bin"

Finally, retrieve required submodules to build this port. This might take a while for the first time:

west espressif update


It is recommended running the command above after west update so that submodules also get updated.


The usual flash target will work with the esp32c3_devkitm board configuration. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b esp32c3_devkitm samples/hello_world
west flash

Refer to Building an Application and Run an Application for more details.

It’s impossible to determine which serial port the ESP32 board is connected to, as it uses a generic RS232-USB converter. The default of /dev/ttyUSB0 is provided as that’s often the assigned name on a Linux machine without any other such converters.

The baud rate of 921600bps is recommended. If experiencing issues when flashing, try halving the value a few times (460800, 230400, 115200, etc).

All flashing options are now handled by the West (Zephyr’s meta-tool) tool, including flashing with custom options such as a different serial port. The west tool supports specific options for the ESP32C3 board, as listed here:

--esp-idf-path ESP_IDF_PATH

path to ESP-IDF

--esp-device ESP_DEVICE

serial port to flash, default $ESPTOOL_PORT if defined. If not, esptool will loop over available serial ports until it finds ESP32 device to flash.

--esp-baud-rate ESP_BAUD_RATE

serial baud rate, default 921600

--esp-flash-size ESP_FLASH_SIZE

flash size, default “detect”

--esp-flash-freq ESP_FLASH_FREQ

flash frequency, default “40m”

--esp-flash-mode ESP_FLASH_MODE

flash mode, default “dio”

--esp-tool ESP_TOOL

if given, complete path to espidf. default is to search for it in [ESP_IDF_PATH]/components/esptool_py/ esptool/

--esp-flash-bootloader ESP_FLASH_BOOTLOADER

Bootloader image to flash

--esp-flash-partition_table ESP_FLASH_PARTITION_TABLE

Partition table to flash

For example, to flash to /dev/ttyUSB2, use the following command after having build the application in the build directory:

west flash -d build/ --skip-rebuild --esp-device /dev/ttyUSB2