Mavlink

Introduction

  1. It is a protocol for communication

  2. Transmit in UART Serial interface

  3. Are Hexadecimal and Octadecimal numbers

Heartbeat Pack

  • Heart beat pack is a special pack which is for “register”, so a device which sanding this pack in a frequency of 2Hz or more can be recognized as a “member” in the whole system.

  • Only member can send a message/command.

Pack example (Heartbeat)

  • packet length = 17 (6 bytes header + 9 bytes payload + 2 bytes checksum)

hdr len seq sys cmp id payload (len 9)---------------------- crc----- 0 1 2 3 4 5 6 7 8 9 a b c d e f 10 FE 09 4E 01 01 00 00 00 00 00 02 03 51 04 03 1C 7F

Fixed Header (6 octets) 0. packet header, always 0xFE 1. message length (for this pack = 9) 2. sequence number -- rolls around from 255 to 0 (0x4e, previous was 0x4d) 3. source system - what system is sending this message (for this example 1) 4. source component - what component of the system is sending the message (for this example 1) 5. message ID (0 = heartbeat)

Variable Sized Payload (specified in octet 1, range 0..255) 06-0e. payload

Packet Checksum 0f-10. CRC25

Robotics Institute 

University of Michigan, Ann Arbor

© 2017 by Bruce Personal Website. 

Updated on 8/21/2017