Support for the Atmel SAM L21 Xplained Pro board. More...
Detailed Description
Support for the Atmel SAM L21 Xplained Pro board.
Overview
The SAML21 Xplained Pro is an ultra-low power evaluation board by Atmel featuring a ATSAML21J18A SoC. The SoC includes a SAML21 ARM Cortex-M0+ micro- controller. For programming the MCU comes with 32Kb of RAM and 256Kb of flash memory.
The saml21-xpro is available from various hardware vendors for ~50USD (as of oct. 2015).
Please note:* ATMEL's most recent SAML21s are the B variant, or ATSAML21J18B. Because the driver changes are mostly small, throughout this reference the device will continue to be referred to as the ATSAML21J18[A/B] indiscriminately;
Hardware
MCU
| MCU | ATSAML21J18A |
|---|---|
| Family | ARM Cortex-M0+ |
| Vendor | Atmel |
| RAM | 32Kb |
| Flash | 256Kb |
| Frequency | up to 48MHz |
| FPU | no |
| Timers | 8 (16-bit) |
| ADCs | 1x 12-bit (20 channels) |
| UARTs | max 6 (shared with SPI and I2C) |
| SPIs | max 6 (see UART) |
| I2Cs | max 6 (see UART) |
| Vcc | 1.8V - 3.6V |
| Datasheet | Datasheet |
| Board Manual | Board Manual |
User Interface
1 User button and 1 LED:
| Device | PIN |
|---|---|
| LED0 | PB10 |
| SW0 (button) | PA02 |
Implementation Status
| Device | ID | Supported | Comments |
|---|---|---|---|
| MCU | saml21 | partly | PLL clock not implemented |
| Low-level driver | GPIO | yes | |
| PWM | no | ||
| UART | yes | ||
| I2C | yes | ||
| SPI | yes | ||
| USB | no | ||
| RTT | yes | ||
| RTC | yes | ||
| RNG | no | ||
| Timer | yes | ||
| ADC | yes |
Flashing the device
Connect the device to your Micro-USB cable using the port labeled as EDBG.
The standard method for flashing RIOT to the saml21-xpro is using OpenOCD. Please note that even the latest official OpenOCD (v0.9 at the time of this writing) does not support B-variant SAML21 devices.
If you attempt to flash a board, and OpenOCD throws a Couldn't find part corresponding to DID XXXXXXXX error, you will need to compile your own OpenOCD from source.
Refer to https://github.com/RIOT-OS/RIOT/wiki/OpenOCD for general instructions on building OpenOCD and make sure "cmsis-dap" and "hidapi-libusb" are enabled.
On Linux you will have to add a udev rule for hidraw, like
Arch Linux
With yaourt:
Ubuntu
Although this refers to setting up the SAMR21, this guide is still very helpful to understanding how to set up a solid RIOT development environment for the SAML21: http://watr.li/samr21-dev-setup-ubuntu.html
Supported Toolchains
For using the saml21-xpro board we strongly recommend the usage of the GNU Tools for ARM Embedded Processors toolchain.
Known Issues / Problems
Stack sizes
The default stack sizes have not been tuned properly yet. If in doubt why your application crashes try increasing the default stack sizes and use ps to find out how much stack is being used. Tracked in https://github.com/RIOT-OS/RIOT/issues/2228
Not flashable by OpenOCD anymore
It can happen that OpenOCD is not able to program the board, because of wrong clock configuration or low power modes. In this case you can use this little tool to erase the flash. Just follow the instructions to build it and run ./edbg -e to erase the flash. Then press the reset button and you're able to program via OpenOCD again.
Files | |
| file | arduino_board.h |
| Board configuration for the Arduino API. | |
| file | arduino_pinmap.h |
| Mapping from board pins to Arduino pins. | |
| file | board.h |
| Board specific definitions for the Atmel SAM L21 Xplained Pro board. | |
| file | gpio_params.h |
| Board specific configuration of direct mapped GPIOs. | |
| file | periph_conf.h |
| Peripheral MCU configuration for the Atmel SAM L21 Xplained Pro board. | |
