Bootloader for Tomu board

This repo contains the bootloader for the EFM32HG Tomu board.

The bootloader is a slightly modified version of the stock EFM32 AN0042 bootloader.

The changes are;

• Use internal oscillator rather than requiring an external Crystal (which doesn't exist on the Tomu).
• Always enter the bootloader, not needing the a pullup on the 'C' pin

The bootloader will identify itself as follows when the i command is pressed;

BOOTLOADER version EFM32HG bootloader v1.a, Chip ID 24A622015669A7A1

The two important parts are version EFM32HG bootloader v1.a

Using

New firmware can be loaded using the u command. Booting the loaded firmware can be done using b.

For a full set of commands see the AN0042 documentation.

Flashing onto Tomu

Tomu's received after February 2017 should come with this bootloader installed. If you got your Tomu at LCA2017 or 33C3, or building your own Tomu board you will need to load the bootloader yourself.

The recommend way to load the bootloader onto a Tomu board is using a RPi with OpenOCD. Instructions for doing this can be found in the openocd directory. You need OpenOCD version 0.10.0 or later to have EFM32HG support.

Building

The firmware requires IAR compiler which is not freely avaliable. Prebuilt versions of the bootloader are available in the prebuilt directory.

We would love someone to port the bootloader to GCC!