ESP32C3 0.42 OLED

Overview

ESP32-C3 0.42 OLED is a mini development board based on the Espressif ESP32-C3 [6] RISC-V WiFi/Bluetooth dual-mode chip.

For more details see the 01space ESP32C3 0.42 OLED [7] Github repo.

Hardware

This board is based on the ESP32-C3-FH4 with WiFi and BLE support. It features:

  • RISC-V SoC @ 160MHz with 4MB flash and 400kB RAM

  • WS2812B RGB serial LED

  • 0.42-inch OLED over I2C

  • Qwiic I2C connector

  • One pushbutton

  • Onboard ceramic chip antenna

  • On-chip USB-UART converter

Note

The RGB led is not supported on this Zephyr board yet.

Note

The ESP32-C3 does not have native USB, it has an on-chip USB-serial converter instead.

ESP32-C3 Features

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.

The features include the following:

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

  • 802.11b/g/n/

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

  • 384 KB ROM

  • 400 KB SRAM (16 KB for cache)

  • 8 KB SRAM in RTC

  • 22 x programmable GPIOs

  • Various peripherals:

    • Full-speed USB Serial/JTAG controller

    • TWAI® compatible with CAN bus 2.0

    • General DMA controller (GDMA)

    • 2x 12-bit SAR ADC with up to 6 channels

    • 3x SPI

    • 2x UART

    • 1x I2S

    • 1x I2C

    • 2 x 54-bit general-purpose timers

    • 3 x watchdog timers

    • 1 x 52-bit system timer

    • Remote Control Peripheral (RMT)

    • LED PWM controller (LEDC) with up to 6 channels

    • Temperature sensor

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

For more information, check the ESP32-C3 Datasheet [1] or the ESP32-C3 Technical Reference Manual [2].

Connections and IOs

See the following image:

01space ESP32C3 0.42 OLED Pinout

01space ESP32C3 0.42 OLED Pinout

It also features a 0.42 inch OLED display, driven by a SSD1306-compatible chip. It is connected over I2C: SDA on GPIO5, SCL on GPIO6.

System Requirements

Binary Blobs

Espressif HAL requires RF 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.

Programming and Debugging

The esp32c3_042_oled board supports the runners and associated west commands listed below.

flash debug rtt attach debugserver
esp32 ✅ (default)
openocd ✅ ✅ (default) ✅ ✅ ✅

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:

  1. Sysbuild

  2. 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 <board> --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 <board> samples/hello_world

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

# From the root of the zephyr repository
west build -b <board> 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! <board>

Board variants using Snippets

ESP32 boards can be assembled with different modules using multiple combinations of SPI flash sizes, PSRAM sizes and PSRAM modes. The snippets under snippets/espressif provide a modular way to apply these variations at build time without duplicating board definitions.

The following snippet-based variants are supported:

Snippet name

Description

Flash memory size

flash-4M

Board with 4MB of flash

flash-8M

Board with 8MB of flash

flash-16M

Board with 16MB of flash

flash-32M

Board with 32MB of flash

PSRAM memory size

psram-2M

Board with 2MB of PSRAM

psram-4M

Board with 4MB of PSRAM

psram-8M

Board with 8MB of PSRAM

PSRAM utilization

psram-reloc

Relocate flash to PSRAM

psram-wifi

Wi-Fi buffers in PSRAM

To apply a board variant, use the -S flag with west build:

west build -b <board> -S flash-32M -S psram-4M samples/hello_world

Note

These snippets are applicable to boards with compatible hardware support for the selected flash/PSRAM configuration.

  • If no FLASH snippet is used, the board default flash size will be used.

  • If no PSRAM snippet is used, the board default psram size will be used.

Debugging

OpenOCD Debugging

Espressif chips require a custom OpenOCD build with ESP32-specific patches. Download the latest release from OpenOCD for ESP32 [3].

For detailed JTAG setup instructions, see JTAG debugging for ESP32 [5].

Zephyr Thread Awareness

OpenOCD supports Zephyr RTOS thread awareness, allowing GDB to:

  • List all threads with info threads

  • Display thread names, priorities, and states

  • Switch between thread contexts

  • Show backtraces for any thread

Requirements:

Example:

# From the root of the zephyr repository
west build -b <board> samples/hello_world -- -DCONFIG_DEBUG_THREAD_INFO=y -DOPENOCD=<path/to/bin/openocd> -DOPENOCD_DEFAULT_PATH=<path/to/openocd/share/openocd/scripts>
west debug

Using a Custom OpenOCD

The Zephyr SDK includes a bundled OpenOCD, but it may not have ESP32 support. To use the Espressif OpenOCD, specify the path when building:

# From the root of the zephyr repository
west build -b <board> samples/hello_world -- -DOPENOCD=/path/to/openocd -DOPENOCD_DEFAULT_PATH=/path/to/openocd/scripts
west debug

References