I am trying to communicate between two boards with a serial port(rs232). One of the requirement is to be able to distinguish which task is sending/receiving data. So need a header field to identify task.
I plan to use asynchronous HDLC frame without caring much for control field. It looks like this
Flag | EOF(1bit)/Seq Number(7bits) | Task | Length | Info(length bytes) | CRC(16 bit) | Flag
Flag value is 0x7E.
I can limit the sequence number and Task and Length value to below 0x7E. So only information and CRC might have 0x7E value which i will replace by byte stuffing.
Almost everywhere i read people talk only about byte stuffing in information field. Is it not possible to get 0x7E in CRC. How do i handle that. Sould i do byte stuffing for CRC aswell if i end up with 0x7E