Solved ATMega328PB PPM Encoder - where can I find Firmware?

[HariUp]

I am using a PWM to PPM Converter Encoder v1.0. from https://www.amazon.co.uk/Trifycore-Receiver-Controller-Aircraft-Component/dp/B07GXGSP3V/
All manuals I've read online talk about an ATMega328p chip being used, but on my board, it clearly reads "pb" on the end, unlike the picture shown on the website above.
I want to be able to reprogram the chip so that it outputs PPM instead of a PPM-Sum signal, but I've no idea how, as I've looked online for my type of encoder chip, but there is no mention of it on any DIY Drone website.
Would it be ok to simply use the 328p firmware on the 328pb?

 

[CampRobber]

Note:  Code compiled for ATmega328 variants are compatible and can be executed in the ATmega328PB device. Whereas, reverse code compatibility is not guaranteed.

https://www.microchip.com/wwwAppNotes/AppNotes.aspx?appnote=en591418

 

[PsyBorg]

Wouldnt this stuff be posted up on github like the guis and all for flight controllers?

 

[HariUp]

Note:  Code compiled for ATmega328 variants are compatible and can be executed in the ATmega328PB device. Whereas, reverse code compatibility is not guaranteed.

Thanks. There is a chance that I won't need to reprogram the Encoder to solve my problem, which is that my FC isn't recognising the outputted PPM signal. But this problem has been more or less solved.