Here is version 1 of the firmware for the Airsoft Rounds Counter project. The code uses avr-gcc but should be real easy to port if you use a different compiler.
This firmware is by no means the final version. Rather, it is the firmware for the breadboarded version (the schematic is here).
The ZIP archive contains three files:
Contains all the code. Please note that the code assumes that a LED is connected to PB4 which is not shown in the schematic. This is purely for debugging purposes and you can add the LED or not. The code doesn't care. And neither do I.
Header file with definitions for the various Max7219 commands.
Standard makefile. Do a 'make all' to compile, 'make fuse' to set fuses (they are set to internal 8 MHz RC oscillator with slow startup, no BOD, SPI enabled), 'make flash' to flash the ATTiny and 'make clean' to delete the binaries.
Download the ZIP archive here: firmware.zip