Build a Space Packet

A CCSDS Space Packet opens with a 6-byte primary header: version, type, a secondary-header flag, an 11-bit APID, sequence flags and count, then a length. Everything after that is the data field. This console can append a 16-bit CRC as packet error control.

Build the flatsat EPS packet. The length field is filled from the data you add — it is the number of data octets minus one, and the CRC counts as data. The CRC is CRC-16/CCITT-FALSE (poly 0x1021, init 0xFFFF, no reflection, xorout 0x0000), the polynomial CCSDS names. A flight ICD also freezes the final XOR.