Any board manufactured from 5. march 2013 or later should have the latest ArduPPM v.2.3.16. If the board was manufactured before that date it will have v2.3.13.
There is no easy way to check the firmware version. It's best to just upgrade to the latest version if you are unsure or have a problem.
But if you want to check here is how:
- First you need to put the 32U2 chip into DFU mode, and use the Atmel FLIP software to load the firmware from the chip and save into a .hex file.
- Then you need to convert the .hex file into readable text using the included "avr-objdump" tool.
- Execute "avr-objdump -s firmware.hex" and the ArduPPM version should then be shown as readable text at the very end of the output.