Adafruit Feather ESP32S2

Overview

The Adafruit Feather ESP32-S2 boards are ESP32-S2 development boards in the Feather standard layout, sharing peripheral placement with other devices labeled as Feathers or FeatherWings. The board is equipped with an ESP32-S2 mini module, a LiPo battery charger, a fuel gauge, a USB-C and SparkFun Qwiic [7]-compatible STEMMA QT [8] connector for the I2C bus.

Hardware

  • ESP32-S2 mini module, featuring the 240MHz Tensilica processor

  • 320KB SRAM, 4MB flash + 2MB PSRAM

  • USB-C directly connected to the ESP32-S2 for USB

  • LiPo connector and built-in battery charging when powered via USB-C

  • LC709203 or MAX17048 fuel gauge for battery voltage and state-of-charge reporting

  • Built-in NeoPixel indicator RGB LED

  • STEMMA QT connector for I2C devices, with switchable power for low-power mode

Note

  • The Adafruit ESP32-S2 Feather with BME280 Sensor [2] is the same board as the Adafruit ESP32-S2 Feather [1] but with an already equipped BME280 Sensor, but is not stated as a separate board, instead the BME280 needs to be added via a devicetree overlay. All boards, except the Adafruit ESP32-S2 Feather with BME280 Sensor [2] have a space for it, but will not be shipped with.

  • As of May 31, 2023 - Adafruit has changed the battery monitor chip from the now-discontinued LC709203 to the MAX17048. Check the back silkscreen of your Feather to see which chip you have.

  • For the MAX17048 a driver in zephyr exists and is supported, but needs to be added via a devicetree overlay.

  • For the LC709203 a driver does’nt exists yet and the fuel gauge for boards with this IC is not available.

  • For the Adafruit ESP32-S2 Feather [1] there are two different Revisions rev B and rev C. The rev C board has revised the power circuitry for the NeoPixel and I2C QT port. Instead of a transistor the rev C has a LDO regulator. To enable the NeoPixel and I2C QT port on rev B boards GPIO7 (i2c_reg) needs to be set to LOW and on rev C boards it needs to be set HIGH.

Supported Features

The adafruit_feather_esp32s2 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_esp32s2
@
/
esp32s2

Type

Location

Description

Compatible

CPU

on-chip

Espressif Xtensa LX7 CPU1

espressif,xtensa-lx7

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 RTC (Power & Clock Controller Module) Module1

espressif,esp32-rtc

Counter

on-chip

ESP32 Counter Driver based on RTC Main Timer1

espressif,esp32-rtc-timer

on-chip

ESP32 general-purpose timers4

espressif,esp32-timer

DAC

on-chip

ESP32 Digital to Analog converter (DAC)1

espressif,esp32-dac

Flash controller

on-chip

ESP32 flash controller1

espressif,esp32-flash-controller

GPIO & Headers

on-chip

ESP32 GPIO controller2

espressif,esp32-gpio

on-board

GPIO pins exposed on Adafruit Feather headers1

adafruit-feather-header

I2C

on-chip

ESP32 I2C1 1

espressif,esp32-i2c

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

LED

on-board

Group of GPIO-controlled LEDs1

gpio-leds

LED strip

on-board

Worldsemi WS2812 LED strip, SPI binding1

worldsemi,ws2812-spi

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

Power domain

on-board

Simple GPIO controlled power domain1

power-domain-gpio

PWM

on-chip

ESP32 LED Control (LEDC)1

espressif,esp32-ledc

RNG

on-chip

ESP32 TRNG (True Random Number Generator)1

espressif,esp32-trng

Sensors

on-chip

ESP32 Pulse Counter (PCNT)1

espressif,esp32-pcnt

on-chip

ESP32 temperature sensor1

espressif,esp32-temp

Serial controller

on-chip

ESP32 UART2

espressif,esp32-uart

SPI

on-chip

ESP32 SPI2

espressif,esp32-spi

Watchdog

on-chip

ESP32 XT Watchdog Timer1

espressif,esp32-xt-wdt

on-chip

ESP32 watchdog1 1

espressif,esp32-watchdog

Wi-Fi

on-chip

ESP32 SoC Wi-Fi1

espressif,esp32-wifi

Note

USB-OTG is until now not supported see ESP32 development overview [4]. To see a serial output a FTDI-USB-RS232 or similar needs to be connected to the RX/TX pins on the feather connector.

Connections and IOs

The Adafruit ESP32-S2 Feather [1] User Guide has detailed information about the board including pinouts and the schematic.

Programming and Debugging

Prerequisites

Espressif HAL requires WiFi binary blobs in order work. Run the command below to retrieve those files.

west update
west blobs fetch hal_espressif

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:

Rev B

west build -b adafruit_feather_esp32s2@B --sysbuild samples/hello_world

Rev C

west build -b adafruit_feather_esp32s2@C --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:

Rev B

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@B samples/hello_world

Rev C

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/hello_world

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

To enter ROM bootloader mode, hold down boot-button while clicking reset button. When in the ROM bootloader, you can upload code and query the chip using west flash.

Rev B

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@B samples/hello_world
west flash

Rev C

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/hello_world
west flash

After the flashing you will receive most likely this Error:

WARNING: ESP32-S2FNR2 (revision v0.0) chip was placed into download mode using GPIO0.
esptool.py can not exit the download mode over USB. To run the app, reset the chip manually.
To suppress this note, set --after option to 'no_reset'.
FATAL ERROR: command exited with status 1: ...

As stated in the Warning-Message esptool can’t reset the board by itself and this message can be ignored and the board needs to be reseted via the Reset-Button manually.

Open the serial monitor using the following command:

west espressif monitor

After the board has been manually reseted and booted, you should see the following message in the monitor:

***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx *****
Hello World! adafruit_feather_esp32s2

Debugging

ESP32-S2 support on OpenOCD is available at OpenOCD [3].

ESP32-S2 has a built-in JTAG circuitry and can be debugged without any additional chip. Only an USB cable connected to the D+/D- pins is necessary.

Further documentation can be obtained from the SoC vendor in JTAG debugging for ESP32-S2 [9].

You can debug an application in the usual way. Here is an example for the Hello World application.

Rev B

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@B samples/hello_world
west debug

Rev C

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/hello_world
west debug

Testing the On-Board-LED

There is a sample available to verify that the LEDs on the board are functioning correctly with Zephyr:

Rev B

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@B samples/basic/blinky
west flash

Rev C

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/basic/blinky
west flash

Testing the NeoPixel

There is a sample available to verify that the NeoPixel on the board are functioning correctly with Zephyr:

Rev B

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@B samples/drivers/led/led_strip
west flash

Rev C

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/drivers/led/led_strip
west flash

Testing the Fuel Gauge (MAX17048)

There is a sample available to verify that the MAX17048 fuel gauge on the board are functioning correctly with Zephyr:

Note

As of May 31, 2023 Adafruit changed the battery monitor chip from the now-discontinued LC709203 to the MAX17048.

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/fuel_gauge/max17048/
west flash

Testing Wi-Fi

There is a sample available to verify that the Wi-Fi on the board are functioning correctly with Zephyr:

Note

The Prerequisites must be met before testing Wi-Fi.

Rev B

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@B samples/net/wifi/shell
west flash

Rev C

# From the root of the zephyr repository
west build -b adafruit_feather_esp32s2@C samples/net/wifi/shell
west flash

References