Here we go again. I am stucked with the same problem again and again.

I am having the same problem again, that is:

• Sending data from arduino to a pc
• Decode the binary structures with construct

CCSDS defines that:

• Bit 0 is the FIRST bit transmitted = MSB.

My conclusions are:

• Sending structs without control it is not useful because is difficult to maintain. It is better to create the buffers like 20230518 - C Binary Data structures
• With little endian systems is difficult to describe bit structs that are sent over systems
• Microcontrollers are sending the data in little endian. So in systems with big endian, and bitstructs is necessary to do a swap. This is the change that is necessary in Python:

d = ByteSwapped(BitStruct(
  "TYPE" / BitsInteger(1),
  "APID" / BitsInteger(6),
  "SECH" / BitsInteger(1),
  "LENGTH" / BitsInteger(8)
))

d.parse(b"\x03\x05")