1.8 KiB
| title | tagline | linkname | x | y |
|---|---|---|---|---|
| ARM Cortex M0+ | Atmel SAM D20 E | armcortex | 49% | 47% |
The board is centred around the Atmel SAM D20 microcontroller. We use the smallest E variant in a QFN-32 package (-M)
The firmware is written in C and can be built using GNU Tools for ARM Embedded Processors See README-samd20-gcc-blackmagic.md for more details.
From the datasheet we can see there's a few RAM/ROM size options:
| -14 | 16 KBytes | 2 KBytes |
| -15 | 32 KBytes | 4 KBytes |
| -16 | 64 KBytes | 8 KBytes |
| -17 | 128 KBytes | 16 KBytes |
| -18 | 256 KBytes | 32 KBytes |
We've been using the -17 variant so far, but may upgrade to the -18 variant if we need more Flash for geofencing or SRAM for backlog.
The SAM D series implements Generic Clocks (GCLKs) which allow us to divide, route and disable clock signals internally as required. These are used particularly for APRS.
Thanks to an error in Revision C silicon we can't configure the correct pin layout for the SERCOM used to talk to the radio. Currently it's just being bit-banged as both Mouser and Farnell appear to have bought large quantities of Revision C silicon. TODO: Fix in future board revision??