V2.1

This version is identical to version 2, except for the compiler version and the new interfaceboard v1.5 version.

Bootloader for the 3devo interface boards. Compiled using avr-gcc 5.4.0 on Cygwin/Windows.

Keep in mind that the I²C and SPI pins are shared, so during programming, no I²C master must be active. The easiest way to do so is to connect programmer reset line to the master reset line, or connect the master reset line to GND directly. Colliding communication transfers could break the slave AtTiny (presumably by setting the fuses to external crystal usage or something similar).

make all BOARD_TYPE=interfaceboard CURRENT_HW_REVISION=0x13 COMPATIBLE_HW_REVISION=0x01
make[1]: Map '/cygdrive/c/GitHub/AtTinyBootloader' wordt binnengegaan

attinybootloader-v2-interfaceboard-1.3.elf:     file format elf32-avr

Contents of section .fuse:
 820000 e2d5f4                               ...
        ^^     Low
          ^^   High
            ^^ Extended
avr-size --format=avr attinybootloader-v2-interfaceboard-1.3.elf
AVR Memory Usage
----------------
Device: Unknown

Program:    2010 bytes
(.text + .data + .bootloader)

Data:        114 bytes
(.data + .bss + .noinit)
...

To set fuses and flash:

$ avrdude -c atmelice_isp -B 4 -p t841 -U lfuse:w:0xe2:m -U hfuse:w:0xd5:m -U efuse:w:0xf4:m -U flash:w:attinybootloader-v2-interfaceboard-1.5.hex

(adapt the -c option for your programmer)