Short update to keep the time interval short:

Lastly we were testing the GRiSP 2 board that got the final System on Module (SoM) hand soldered on (we needed to upgrade it to a beefier one because we need 2xUSB outputs).

Booting Erlang from SD-card succeeded after a bit of debugging and bootloader tweaking it also connected to Wifi (which we couldn't test before because it needs the second USB) and Erlang distribution works via Wifi!

But now we have a second option to boot from and that is a eMMC on the SoM (eMMC is basically a soldered on SD-card chip with more data lanes and therefore faster).

While trying to also boot Erlang from eMMC we accidentally bricked the board because the bootloader is also stored on eMMC and we forgot to add it to the image we were writing.

That was a important test of which we learned:

  • Documentation needs improving (if it happens to us it will happen to you too)
  • We will make the tooling to build eMMC images in a way that it will be very hard not to add a bootloader
  • We also learned that un-bricking was not working as expected: one can install a new bootloader via serial line or by booting the bootloader from the SD-card. The latter would be the most convenient but one of the jumpers that needed to be set to activated this was missing on the board!

So we actually improved the hardware by these tests.

This wee we will get the board back from the HW devs with this jumper added and we will retest - this time we will intentionally erase the bootloader and see that we can get out of this predicament.

Soon production of the boards can start!