use avrdude linuxspi/linuxgpio programmer

[chrstphrchvz]

As long as the linuxspi or linuxgpio programmers were enabled at compile time, there shouldn't be a need for patching avrdude with a separate programmer for alamode. Arduino IDE (not through Raspbian) includes avrdude with the linuxgpio programmer, and the Raspbian build of avrdude also includes the linuxspi programmer.

I haven't figured out all the steps to successfully use this myself, but it would probably involve updating the avrdude.conf and/or programmers.txt.

(n.b.: I think this is what ArduBerry is using.)

[chrstphrchvz]

Update: I successfully flashed the optiboot_atmega328.hex bootloader and uploaded a sketch to the alamode using the both the linuxgpio and linuxspi programmers. E.g. for linuxspi, in avrdude.conf I specified reset on gpio pin 18 (header pin 12):

programmer
  id = "linuxspi";
  desc = "Use Linux SPI device in /dev/spidev*";
  type = "linuxspi";
  reset = 18;
  baudrate=400000;
;

To clarify, the linuxspi programmer is not yet officially included in avrdude nor the official Arduino IDE download's avrdude, rather it is a patch that debian and probably others downstream include by popular demand.

I haven't yet figured out how to have this appear in the Arduino IDE, but there might also still be a bug in either avrdude or udev that pose an issue trying it out anyways (sleeping long enough for udev to fix permissions on the gpio sysfs stuff; I ran avrdude as root as a workaround).

[chrstphrchvz]

Update: as of sometime later in 2018, Arduino's avrdude now includes linuxspi.