Espressif ESP32-S3

The ESP32-S3 is a series of single and dual-core SoCs from Espressif based on Harvard architecture Xtensa LX7 CPUs and with on-chip support for Bluetooth and Wi-Fi.

All embedded memory, external memory and peripherals are located on the data bus and/or the instruction bus of these CPUs. With some minor exceptions, the address mapping of two CPUs is symmetric, meaning they use the same addresses to access the same memory. Multiple peripherals in the system can access embedded memory via DMA.

On dual-core SoCs, the two CPUs are typically named “PRO_CPU” and “APP_CPU” (for “protocol” and “application”), however for most purposes the two CPUs are interchangeable.

ESP32-S3 Toolchain

The toolchain used to build ESP32-S3 firmware can be either downloaded or built from the sources. It is highly recommended to use (download or build) the same toolchain version that is being used by the NuttX CI.

Please refer to the Docker container and check for the current compiler version being used. For instance:

###############################################################################
# Build image for tool required by ESP32 builds
###############################################################################
FROM nuttx-toolchain-base AS nuttx-toolchain-esp32
# Download the latest ESP32 GCC toolchain prebuilt by Espressif
RUN mkdir -p xtensa-esp32-elf-gcc && \
  curl -s -L "https://github.com/espressif/crosstool-NG/releases/download/esp-12.2.0_20230208/xtensa-esp32-elf-12.2.0_20230208-x86_64-linux-gnu.tar.xz" \
  | tar -C xtensa-esp32-elf-gcc --strip-components 1 -xJ

RUN mkdir -p xtensa-esp32s2-elf-gcc && \
  curl -s -L "https://github.com/espressif/crosstool-NG/releases/download/esp-12.2.0_20230208/xtensa-esp32s2-elf-12.2.0_20230208-x86_64-linux-gnu.tar.xz" \
  | tar -C xtensa-esp32s2-elf-gcc --strip-components 1 -xJ

RUN mkdir -p xtensa-esp32s3-elf-gcc && \
  curl -s -L "https://github.com/espressif/crosstool-NG/releases/download/esp-12.2.0_20230208/xtensa-esp32s3-elf-12.2.0_20230208-x86_64-linux-gnu.tar.xz" \
  | tar -C xtensa-esp32s3-elf-gcc --strip-components 1 -xJ

For ESP32-S3, the toolchain version is based on GGC 12.2.0 (xtensa-esp32s3-elf-12.2.0_20230208)

Building from source

You can also build the toolchain yourself. The steps to build the toolchain with crosstool-NG on Linux are as follows

$ git clone https://github.com/espressif/crosstool-NG.git
$ cd crosstool-NG
$ git submodule update --init

$ ./bootstrap && ./configure --enable-local && make

$ ./ct-ng xtensa-esp32s3-elf
$ ./ct-ng build

$ chmod -R u+w builds/xtensa-esp32s3-elf

$ export PATH="crosstool-NG/builds/xtensa-esp32-elf/bin:$PATH"

These steps are given in the setup guide in ESP-IDF documentation.

Building and flashing NuttX

Bootloader and partitions

Nuttx can boot the ESP32-S3 directly using the so-called “Simple Boot”. An externally-built 2nd stage bootloader is not required in this case as all functions required to boot the device are built within Nuttx. Simple boot does not require any specific configuration (it is selectable by default if no other 2nd stage bootloader is used).

If other features are required, an externally-built 2nd stage bootloader is needed. The bootloader is built using the make bootloader command. This command generates the firmware in the nuttx folder. The ESPTOOL_BINDIR is used in the make flash command to specify the path to the bootloader. For compatibility among other SoCs and future options of 2nd stage bootloaders, the commands make bootloader and the ESPTOOL_BINDIR option (for the make flash) can be used even if no externally-built 2nd stage bootloader is being built (they will be ignored if Simple Boot is used, for instance):

$ make bootloader

Note

It is recommended that if this is the first time you are using the board with NuttX to perform a complete SPI FLASH erase.

$ esptool.py erase_flash

Building and Flashing

First, make sure that esptool.py is installed. This tool is used to convert the ELF to a compatible ESP32-S3 image and to flash the image into the board. It can be installed with: pip install esptool==4.8.dev4.

It’s a two-step process where the first converts the ELF file into an ESP32-S3 compatible binary and the second flashes it to the board. These steps are included in the build system and it is possible to build and flash the NuttX firmware simply by running:

$ make flash ESPTOOL_PORT=<port> ESPTOOL_BINDIR=./

where <port> is typically /dev/ttyUSB0 or similar. ESPTOOL_BINDIR=./ is the path of the externally-built 2nd stage bootloader and the partition table (if applicable): when built using the make bootloader, these files are placed into nuttx folder. ESPTOOL_BAUD is able to change the flash baudrate if desired.

Peripheral Support

The following list indicates the state of peripherals’ support in NuttX:

Peripheral

Support

NOTES

ADC

YES

AES

YES

Bluetooth

No

CAMERA

No

CAN/TWAI

Yes

DMA

Yes

eFuse

No

GPIO

Yes

I2C

No

I2S

Yes

LCD

No

LED_PWM

No

MCPWM

No

Pulse_CNT

No

RMT

No

RNG

No

RSA

No

RTC

Yes

SD/MMC

No

SDIO

No

SHA

No

SPI

Yes

SPIFLASH

Yes

SPIRAM

Yes

Timers

Yes

Touch

Yes

UART

Yes

USB OTG

No

USB SERIAL

Yes

Watchdog

Yes

Wi-Fi

Yes

WPA3-SAE supported

Wi-Fi

Tip

Boards usually expose a wifi defconfig which enables Wi-Fi. On ESP32-S3, SMP is enabled to enhance Wi-Fi performance.

A standard network interface will be configured and can be initialized such as:

nsh> ifup wlan0
nsh> wapi psk wlan0 mypasswd 3
nsh> wapi essid wlan0 myssid 1
nsh> renew wlan0

In this case a connection to AP with SSID myssid is done, using mypasswd as password. IP address is obtained via DHCP using renew command. You can check the result by running ifconfig afterwards.

Tip

Please refer to ESP32 Wi-Fi Station Mode for more information.

Wi-Fi SoftAP

It is possible to use ESP32-S3 as an Access Point (SoftAP).

Tip

Boards usually expose a sta_softap defconfig which enables Wi-Fi (STA + SoftAP). On ESP32-S3, SMP is enabled to enhance Wi-Fi performance.

If you are using this board config profile you can run these commands to be able to connect your smartphone or laptop to your board:

nsh> ifup wlan1
nsh> dhcpd_start wlan1
nsh> wapi psk wlan1 mypasswd 3
nsh> wapi essid wlan1 nuttxap 1

In this case, you are creating the access point nuttxapp in your board and to connect to it on your smartphone you will be required to type the password mypasswd using WPA2.

Tip

Please refer to ESP32 Wi-Fi SoftAP Mode for more information.

The dhcpd_start is necessary to let your board to associate an IP to your smartphone.

Supported Boards