Adafruit Feather ESP32

Board Overview

Adafruit Feather ESP32

Name:

adafruit_feather_esp32

Vendor:

Adafruit Industries, LLC

Architecture:

xtensa

SoC:

esp32

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Overview

The Adafruit ESP32 Feather is an ESP32-based development board using the Feather standard layout.

Hardware

It features the following integrated components:

• ESP32-PICO-V3-02 chip (240MHz dual core, Wi-Fi + BLE)

• 520KB SRAM

• USB-C port connected to USB to Serial converter

• LiPo battery connector and charger

• Charging indicator LED and user LED

• NeoPixel RGB LED

• Reset and user buttons

• STEMMA QT I2C connector

ESP32 Features

• 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

  • 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

  • Temperature sensor

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

• 5uA deep sleep current

Asymmetric Multiprocessing (AMP)

ESP32 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 Inter-Processor Communication (IPC) folder as code reference.

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

Supported Features

The adafruit_feather_esp32 board supports the hardware features listed below.

on-chip / on-board

Feature integrated in the SoC / present on the board.

2 / 2

Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.

vnd,foo

Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

adafruit_feather_esp32@2/esp32/appcpu target

Type	Location	Description	Compatible
CPU	on-chip	Espressif Xtensa LX6 CPU2	espressif,xtensa-lx6
ADC	on-chip	ESP32 ADC2	espressif,esp32-adc
Bluetooth	on-chip	Bluetooth HCI for Espressif ESP321	espressif,esp32-bt-hci
CAN	on-chip	ESP32 Two-Wire Automotive Interface (TWAI)1	espressif,esp32-twai
Clock control	on-chip	ESP32 Clock (Power & Clock Controller Module) Module1	espressif,esp32-clock
Counter	on-chip	ESP32 Counter Driver based on RTC Main Timer1	espressif,esp32-rtc-timer
	on-chip	ESP32 general-purpose timers4	espressif,esp32-timer
	on-chip	ESP32 counters4	espressif,esp32-counter
DAC	on-chip	ESP32 Digital to Analog converter (DAC)1	espressif,esp32-dac
Ethernet	on-chip	ESP32 Ethernet1	espressif,esp32-eth
Flash controller	on-chip	ESP32 flash controller1	espressif,esp32-flash-controller
GPIO & Headers	on-chip	ESP32 GPIO controller2	espressif,esp32-gpio
I2C	on-chip	ESP32 I2C2	espressif,esp32-i2c
I2S	on-chip	ESP32 I2S2	espressif,esp32-i2s
Input	on-chip	ESP32 touch sensor input1	espressif,esp32-touch
Interrupt controller	on-chip	ESP32 Interrupt controller1	espressif,esp32-intc
IPM	on-chip	ESP32 soft inter processor message1	espressif,esp32-ipm
Mailbox	on-chip	ESP32 soft mailbox1	espressif,mbox-esp32
MDIO	on-chip	ESP32 MDIO controller1	espressif,esp32-mdio
Memory controller	on-chip	ESP32 pseudo-static RAM controller1	espressif,esp32-psram
MTD	on-chip	Flash node1	soc-nv-flash
	on-chip	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
Pin control	on-chip	ESP32 pin controller1	espressif,esp32-pinctrl
PWM	on-chip	ESP32 LED Control (LEDC)1	espressif,esp32-ledc
	on-chip	ESP32 Motor Control Pulse Width Modulator (MCPWM)2	espressif,esp32-mcpwm
RNG	on-chip	ESP32 TRNG (True Random Number Generator)1	espressif,esp32-trng
SDHC	on-chip	ESP32 SDHC controller1	espressif,esp32-sdhc
	on-chip	ESP32 SDHC controller slot2	espressif,esp32-sdhc-slot
Sensors	on-chip	ESP32 Pulse Counter (PCNT)1	espressif,esp32-pcnt
Serial controller	on-chip	ESP32 UART3	espressif,esp32-uart
SPI	on-chip	ESP32 SPI2	espressif,esp32-spi
SRAM	on-chip	Generic on-chip SRAM2	mmio-sram
Watchdog	on-chip	ESP32 watchdog1 1	espressif,esp32-watchdog
Wi-Fi	on-chip	ESP32 SoC Wi-Fi1	espressif,esp32-wifi

adafruit_feather_esp32@2/esp32/procpu target

Type	Location	Description	Compatible
CPU	on-chip	Espressif Xtensa LX6 CPU2	espressif,xtensa-lx6
ADC	on-chip	ESP32 ADC2	espressif,esp32-adc
Bluetooth	on-chip	Bluetooth HCI for Espressif ESP321	espressif,esp32-bt-hci
CAN	on-chip	ESP32 Two-Wire Automotive Interface (TWAI)1	espressif,esp32-twai
Clock control	on-chip	ESP32 Clock (Power & Clock Controller Module) Module1	espressif,esp32-clock
Counter	on-chip	ESP32 Counter Driver based on RTC Main Timer1	espressif,esp32-rtc-timer
	on-chip	ESP32 general-purpose timers4	espressif,esp32-timer
	on-chip	ESP32 counters4	espressif,esp32-counter
DAC	on-chip	ESP32 Digital to Analog converter (DAC)1	espressif,esp32-dac
Ethernet	on-chip	ESP32 Ethernet1	espressif,esp32-eth
Flash controller	on-chip	ESP32 flash controller1	espressif,esp32-flash-controller
GPIO & Headers	on-chip	ESP32 GPIO controller2	espressif,esp32-gpio
I2C	on-chip	ESP32 I2C1 1	espressif,esp32-i2c
I2S	on-chip	ESP32 I2S2	espressif,esp32-i2s
Input	on-chip	ESP32 touch sensor input1	espressif,esp32-touch
	on-board	Group of GPIO-bound input keys1	gpio-keys
Interrupt controller	on-chip	ESP32 Interrupt controller1	espressif,esp32-intc
IPM	on-chip	ESP32 soft inter processor message1	espressif,esp32-ipm
LED	on-board	Group of GPIO-controlled LEDs1	gpio-leds
LED strip	on-board	Worldsemi WS2812 LED strip, SPI binding1	worldsemi,ws2812-spi
Mailbox	on-chip	ESP32 soft mailbox1	espressif,mbox-esp32
MDIO	on-chip	ESP32 MDIO controller1	espressif,esp32-mdio
Memory controller	on-chip	ESP32 pseudo-static RAM controller1	espressif,esp32-psram
MTD	on-chip	Flash node1	soc-nv-flash
	on-chip	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
Pin control	on-chip	ESP32 pin controller1	espressif,esp32-pinctrl
PWM	on-chip	ESP32 LED Control (LEDC)1	espressif,esp32-ledc
	on-chip	ESP32 Motor Control Pulse Width Modulator (MCPWM)2	espressif,esp32-mcpwm
RNG	on-chip	ESP32 TRNG (True Random Number Generator)1	espressif,esp32-trng
SDHC	on-chip	ESP32 SDHC controller1	espressif,esp32-sdhc
	on-chip	ESP32 SDHC controller slot2	espressif,esp32-sdhc-slot
Sensors	on-chip	ESP32 Pulse Counter (PCNT)1	espressif,esp32-pcnt
Serial controller	on-chip	ESP32 UART2 1	espressif,esp32-uart
SPI	on-chip	ESP32 SPI1 1	espressif,esp32-spi
SRAM	on-chip	Generic on-chip SRAM2	mmio-sram
Watchdog	on-chip	ESP32 watchdog1 1	espressif,esp32-watchdog
Wi-Fi	on-chip	ESP32 SoC Wi-Fi1	espressif,esp32-wifi

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 adafruit_feather_esp32 board supports the runners and associated west commands listed below.

	flash	debug	debugserver	rtt	attach
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

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 for ESP32 [3].

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.

Further documentation can be obtained from the SoC vendor in JTAG debugging for ESP32 [4].

Here is an example for building the Hello World application.

# From the root of the zephyr repository
west build -b <board> 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 <board> samples/hello_world
west debug

Testing

On-board LED

Test the functionality of the user LED connected to pin 13 with the blinky sample program.

# From the root of the zephyr repository
west build -b adafruit_feather_esp32/esp32/procpu samples/basic/blinky
west flash

NeoPixel

Test the on-board NeoPixel using the led_strip sample program.

# From the root of the zephyr repository
west build -b adafruit_feather_esp32/esp32/procpu samples/drivers/led/led_strip
west flash

User button

Test the button labeled SW38 using the button input sample program.

# From the root of the zephyr repository
west build -b adafruit_feather_esp32/esp32/procpu samples/basic/button
west flash

Wi-Fi

Test ESP32 Wi-Fi functionality using the Wi-Fi shell module.

Note

The hal_espressif blobs must be fetched first.

# From the root of the zephyr repository
west build -b adafruit_feather_esp32/esp32/procpu samples/net/wifi/shell
west flash

References

[1]

https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf

[2]

https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf

[3]

https://github.com/espressif/openocd-esp32/releases

[4]

https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/jtag-debugging/index.html