ESP32-EVB

Overview

The Olimex ESP32-EVB is an OSHW certified, open-source IoT board based on the Espressif ESP32-WROOM-32E/UE module. It has a wired 100Mbit/s Ethernet Interface, Bluetooth LE, WiFi, infrared remote control, and CAN connectivity. Two relays allows switching power appliances on and off.

The board can operate from a single LiPo backup battery as it has an internal LiPo battery charger. There is no step-up converter, so relays, CAN, and USB power does not work when running off battery.

Hardware

  • ESP32-WROOM-32E/UE module with 4MB flash.

  • On-board programmer, CH340T USB-to-UART

  • WiFi, Bluetooth LE connectivity.

  • 100Mbit/s Ethernet interface, Microchip LAN8710A PHY.

  • MicroSD card slot.

  • 2 x 10A/250VAC (15A/120VAC 15A/24VDC) relays with connectors and status LEDs.

  • CAN interface, Microchip MCP2562-E high-speed CAN transceiver.

  • IR receiver and transmitter, up to 5 meters distance.

  • BL4054B LiPo battery charger with status LEDs for stand-alone operation during power outages.

  • Power jack for external 5VDC power supply.

  • Univeral EXTension (UEXT) connector for connecting UEXT modules.

  • User push button.

  • 40 pin GPIO connector with all ESP32 pins.

For more information about the ESP32-EVB and the ESP32-WROOM-32E/UE module, see these reference documents:

Supported Features

The olimex_esp32_evb board configuration supports the following hardware features:

Interface

Controller

Driver/Component

EFUSE

on-chip

hwinfo, device ID

FLASH

module

External flash

GPIO

on-chip

gpio

I2C

on-chip

I2C

INTERRUPT

on-chip

interrupt controller

IO_MUX

on-chip

pinctrl

SPI

on-chip

spi

TIMG

on-chip

counter

TRNG

on-chip

entropy

TWAI

on-chip

CAN controller

UART

on-chip

uart

WDT

on-chip

watchdog

WiFi

on-chip

WiFi

The default configuration can be found in boards/olimex/olimex_esp32_evb/olimex_esp32_evb_appcpu_defconfig and boards/olimex/olimex_esp32_evb/olimex_esp32_evb_procpu_defconfig

Other hardware features are not currently supported by the port.

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:

  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 olimex_esp32_evb --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 olimex_esp32_evb/esp32/procpu samples/hello_world

The usual flash target will work with the olimex_esp32_evb board configuration. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b olimex_esp32_evb/esp32/procpu 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! olimex_esp32_evb

Debugging

As with much custom hardware, the ESP32 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 [5].

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 olimex_esp32_evb/esp32/procpu 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 olimex_esp32_evb/esp32/procpu samples/hello_world
west debug

References