ESP32-DEVKITC-WROOM

Overview

ESP32-DEVKITC-WROOM is a series of low cost, low power system on a chip microcontrollers with integrated Wi-Fi & dual-mode Bluetooth. The ESP32 series employs a Tensilica Xtensa LX6 microprocessor in both dual-core and single-core variations. ESP32-WROOM is created and developed by Espressif Systems, a Shanghai-based Chinese company, and is manufactured by TSMC using their 40nm process. [1]

The features include the following:

Dual core Xtensa microprocessor (LX6), running at 160 or 240MHz
520KB of SRAM
802.11b/g/n/e/i
Bluetooth v4.2 BR/EDR and BLE
Various peripherals:
- 12-bit ADC with up to 18 channels
- 2x 8-bit DACs
- 10x touch sensors
- Temperature sensor
- 4x SPI
- 2x I2S
- 2x I2C
- 3x UART
- SD/SDIO/MMC host
- Slave (SDIO/SPI)
- Ethernet MAC
- CAN bus 2.0
- IR (RX/TX)
- Motor PWM
- LED PWM with up to 16 channels
- Hall effect sensor
Cryptographic hardware acceleration (RNG, ECC, RSA, SHA-2, AES)
5uA deep sleep current

Asymmetric Multiprocessing (AMP)

ESP32-DEVKITC-WROOM allows 2 different applications to be executed in ESP32 SoC. Due to its dual-core architecture, each core can be enabled to execute customized tasks in stand-alone mode and/or exchanging data over OpenAMP framework. See IPC Samples folder as code reference.

Supported Features

Current Zephyr’s ESP32-WROOM board supports the following features:

Interface	Controller	Driver/Component

UART	on-chip	serial port
GPIO	on-chip	gpio
PINMUX	on-chip	pinmux
USB-JTAG	on-chip	hardware interface
SPI Master	on-chip	spi
Timers	on-chip	counter
Watchdog	on-chip	watchdog
TRNG	on-chip	entropy
LEDC	on-chip	pwm
MCPWM	on-chip	pwm
PCNT	on-chip	qdec
SPI DMA	on-chip	spi
TWAI	on-chip	can
ADC	on-chip	adc
DAC	on-chip	dac
Wi-Fi	on-chip
Bluetooth	on-chip

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

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 esp32_devkitc_wroom samples/hello_world

The usual flash target will work with the esp32_devkitc_wroom board configuration. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b esp32_devkitc_wroom 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! esp32_devkitc_wroom

Debugging

ESP32-DEVKITC-WROOM support on OpenOCD is available upstream as of version 0.12.0. Download and install OpenOCD from OpenOCD.

On the ESP-WROOM-32 DevKitC board, the JTAG pins are not run to a standard connector (e.g. ARM 20-pin) and need to be manually connected to the external programmer (e.g. a Flyswatter2):

ESP32 pin	JTAG pin
3V3	VTRef
EN	nTRST
IO14	TMS
IO12	TDI
GND	GND
IO13	TCK
IO15	TDO

Further documentation can be obtained from the SoC vendor in JTAG debugging for ESP32.

Here is an example for building the Hello World application.

# From the root of the zephyr repository
west build -b esp32_devkitc_wroom samples/hello_world
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 esp32_devkitc_wroom samples/hello_world
west debug

Note on Debugging with GDB Stub

GDB stub is enabled on ESP32.

When adding breakpoints, please use hardware breakpoints with command hbreak. Command break uses software breakpoints which requires modifying memory content to insert break/trap instructions. This does not work as the code is on flash which cannot be randomly accessed for modification.