Message Format

Communication over serial port is handled in the form of data packets forming individual messages to- and from the device.

Messages sent by a host device (microcontroller, PC etc.) to the AHRS device are referred as request messages, while messages that AHRS device sends to the host device are referred as response messages.

Both message types have the same structure and they are composed of:

two header bytes identifying message data packet
message ID byte
two bytes value (little endian) containing payload length
a number of payload data bytes
single byte of a payload checksum

Any 16-bit or 32-bit integer values have little endian encoding.

The checksum value is a calculated byte-base sum of all message bytes (except the checksum one) modulo 256.

Table 1. Serial protocol message structure
Header Bytes	Message ID	Payload Length	Payload	Checksum
0x05 0xD3	byte	low_byte, high_byte	...	byte