Board: Samr21 xpro
The SAMR21 Xplained Pro is a compact evaluation board by Atmel featuring a ATSAMR21G18A SoC. The SoC includes a SAMD21 ARM Cortex-M0+ micro-controller bundled with Atmel's AT86RF233, a 2.4GHz IEEE802.15.4 compatible radio. For programming the MCU comes with 32Kb of RAM and 256Kb of flash memory.
The samr21-xpro is available from various hardware vendors for ~40EUR (as of sep. 2014).
| MCU | ATSAMR21G18A |
|---|---|
| Family | ARM Cortex-M0+ |
| Vendor | Atmel |
| RAM | 32Kb |
| Flash | 256Kb |
| Frequency | up to 48MHz |
| FPU | no |
| Timers | 6 (1x 16-bit, 2x 24-bit, 3x 32-bit) |
| ADCs | 1x 12-bit (8 channels) |
| UARTs | max 5 (shared with SPI and I2C) |
| SPIs | max 5 (see UART) |
| I2Cs | max 5 (see UART) |
| Vcc | 1.8V - 3.6V |
| Datasheet | Datasheet |
| Board Manual | Board Manual |
1 User button and 1 LED:
| Device | PIN |
|---|---|
| LED0 | PA19 |
| SW0 (button) | PA28 |
The SAMR21 SoC includes an on-chip AT86RF233 radio. It is internally connected via SPI and some GPIO pins and behaves in exact the same way as externally connected SPI devices.
| Sensor | AT86RF233 |
|---|---|
| Type | 2.4GHz IEEE802.14.4 radio |
| Vendor | Atmel |
| Datasheet | See CPU datasheet |
| Connected to | SPI_0 |
| Pin Config: | |
| Device | SERCOM4 |
| MOSI | PB30 (OUT, SPI mosi) |
| MISO | PC19 (IN, SPI miso) |
| SCLK | PC18 (OUT, SPI sclk) |
| CS | PB31 (OUT, GPIO output) |
| IRQ | PB00 (IN, GPIO external interrupt) |
| RSTN | PB15 (OUT, GPIO output) |
| SLP_TR | PA20 (OUT, GPIO output) |
| Device | ID | Supported | Comments |
|---|---|---|---|
| MCU | samd21 | partly | Energy saving modes not fully utilized |
| Low-level driver | GPIO | yes | |
| PWM | no | ||
| UART | partly | only one UART by now | |
| I2C | no | ||
| SPI | no | ||
| USB | no | ||
| RTT | no | in progress | |
| RNG | no | no HW module | |
| Timer | partly | currently driven in 16 bit mode at 125kHz | |
| Radio Chip | AT86RF233 | no | at86rf231 driver need to be adapted |
The standard method for flashing RIOT to the samr21-xpro is using OpenOCD. For this to work properly, you have to make sure to use a very recent version of OpenOCD.
Follow the instructions of this tutorial: http://karibe.co.ke/2013/08/setting-up-linux-opensource-build-and-debug-tools-for-freescale-freedom-board-frdm-kl25z/
Connect the device to your Micro-USB cable using the port labeled as EDBG.
For using the samr21-xpro board we strongly recommend the usage of the GNU Tools for ARM Embedded Processors toolchain.