General information about the ESP32 port

The ESP32 is a popular WiFi and Bluetooth enabled System-on-Chip (SoC) by Espressif Systems.

Multitude of boards

There is a multitude of modules and boards from different sources which carry the ESP32 chip. MicroPython tries to provide a generic port which would run on as many boards/modules as possible, but there may be limitations. Espressif development boards are taken as reference for the port (for example, testing is performed on them). For any board you are using please make sure you have a datasheet, schematics and other reference materials so you can look up any board-specific functions.

To make a generic ESP32 port and support as many boards as possible the following design and implementation decision were made:

  • GPIO pin numbering is based on ESP32 chip numbering. Please have the manual/pin diagram of your board at hand to find correspondence between your board pins and actual ESP32 pins.

  • All pins are supported by MicroPython but not all are usable on any given board. For example pins that are connected to external SPI flash should not be used, and a board may only expose a certain selection of pins.

Technical specifications and SoC datasheets

The datasheets and other reference material for ESP32 chip are available from the vendor site: https://www.espressif.com/en/support/download/documents?keys=esp32 . They are the primary reference for the chip technical specifications, capabilities, operating modes, internal functioning, etc.

For your convenience, some of technical specifications are provided below:

  • Architecture: Xtensa Dual-Core 32-bit LX6

  • CPU frequency: up to 240MHz

  • Total RAM available: 528KB (part of it reserved for system)

  • BootROM: 448KB

  • Internal FlashROM: none

  • External FlashROM: code and data, via SPI Flash; usual size 4MB

  • GPIO: 34 (GPIOs are multiplexed with other functions, including external FlashROM, UART, etc.)

  • UART: 3 RX/TX UART (no hardware handshaking), one TX-only UART

  • SPI: 4 SPI interfaces (one used for FlashROM)

  • I2C: 2 I2C (bitbang implementation available on any pins)

  • I2S: 2

  • ADC: 12-bit SAR ADC up to 18 channels

  • DAC: 2 8-bit DACs

  • RMT: 8 channels allowing accurate pulse transmit/receive

  • Programming: using BootROM bootloader from UART - due to external FlashROM and always-available BootROM bootloader, the ESP32 is not brickable

For more information see the ESP32 datasheet: https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf

MicroPython is implemented on top of the ESP-IDF, Espressif’s development framework for the ESP32. This is a FreeRTOS based system. See the ESP-IDF Programming Guide for details.