Flash over UART

[COKPOWEHEU]

It would be nice to implement programming via UART. I can implement this myself, but right now your code is very cohesive. You will have to tear off all references to the USB and put it in a module that can be replaced with a uart. At the same time, the isp commands themselves are almost identical. Bytes (0x57, 0xAB) are added at the beginning and a checksum (sum of all bytes except 0x57, 0xAB) at the end. For reception at the beginning, not 0x57, 0xAB, but 0x55, 0xAA. This will require refactoring the entire source file. Should I do this or just redo everything from scratch in my fork?