General information about the SAMD port¶
The SAMD21/SAMD51 MCU family is a high performance family of devices made by MicroChip. The SAMD21 devices are based on an ARM M0+ core, the SAMD51 device on ARM Cortex M4 core. They provide many on-chip I/O units for building small to medium sized devices.
Multitude of boards¶
There is a multitude of modules and boards from different sources which carry an SAMD21/SAMD51 chip. MicroPython aims to provide a generic port which runs on as many boards/modules as possible, but there may be limitations. The Adafruit ItsyBitsy M0 Express, Adafruit Feather M4 Express and the Adafruit ItsyBitsy M4 Express 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 data sheet, schematics and other reference materials so you can look up any board-specific functions.
The following boards are at the moment supported by the port:
ADAFRUIT FEATHER M0 EXPRESS
ADAFRUIT FEATHER M4 EXPRESS
ADAFRUIT ITSYBITSY M0 EXPRESS
ADAFRUIT ITSYBITSY M4 EXPRESS
ADAFRUIT TRINKET M0
MINISAM M4
SAMD21 XPLAINED PRO
SEEED WIO TERMINAL
SEEED XIAO
To make a generic SAMD port and support as many boards as possible the following design and implementation decision were made:
GPIO pin numbering is based on the board numbering. Please have the manual/pin diagram of your board at hand to find correspondence between your board pins and actual SAMD21/SAMD51 pins. For the boards listed above, the relation between the board pin number and the GPIO number can be found at Pinout for the SAMD machine modules.
The pins that can be used by MicroPython are limited to those listed in the board definition files.
Technical specifications and SoC data sheets¶
The data sheets and other reference material for SAMD21/SAMD51 chip are available from the vendor site: https://www.microchip.com/en-us/products/microcontrollers-and-microprocessors/32-bit-mcus/sam-32-bit-mcus They are the primary reference for the chip technical specifications, capabilities, operating modes, internal functioning, etc.
For your convenience, a few technical specifications are provided below:
SAMD21:
Architecture: ARM Cortex M0+
CPU frequency: up to 48MHz
Total RAM available: up to 32 kB (see table)
Internal FlashROM: up to 256 kB Some boards provide additional external SPI flash.
GPIO: up to 52 (GPIOs are multiplexed with other functions, including external FlashROM, UART, etc.)
UART: up to 6 serial devices, which can used for UART, SPI or I2C.
I2S: 1 I2S interfaces
ADC: One 12-bit SAR ADC converter with 16 channels.
Programming: using BootROM bootloader from USB.
SAMD51:
Architecture: ARM Cortex M4
CPU frequency: up to 120MHz
Total RAM available: up to 256 kB
Internal FlashROM: up to 1 MB Some boards provide additional external SPI flash.
GPIO: up to 99 (GPIOs are multiplexed with other functions, including external FlashROM, UART, etc.)
UART: up to 8 serial devices, which can used for UART, SPI or I2C.
I2S: 1 I2S interfaces
ADC: Dual 12-bit SAR ADC converter with 16 channels.
Programming: using BootROM bootloader from USB.
For more information see the excellent SAMD21/SAMD51 data sheets or reference manuals.
At the moment, the SAM21 port of MicroPython requires 256kB flash, of which 64kB is used for a small file system. The SAM51 port requires 512 kB of flash, of which all flash beyond 384kB is used for a file system. Some boards have additional flash memory, which can be used as additional file space.