ardupilot/libraries/AP_Frsky_Telem/AP_Frsky_MAVlite.h

33 lines
1.2 KiB
C

#pragma once
/*
Wire Protocol:
Several SPort packets make up a MAVlite message.
A maximum of six relevant data bytes are present in an SPort packet.
Each SPort packet starts with a sequence number, starting with zero.
If the sequence number is zero then the parser is reset.
The first sport packet contains len at offset 1. It is the
*payload* length - does not include checksum, for example. msgid is
at offset 2, then payload bytes.
Subsequent SPort packets contain a sequence number at offset zero,
followed by more payload bytes.
When sufficient payload bytes have been received (based on "len"), a
single checksum byte arrives. Sometimes this checksum byte goes
into an SPort packet all on its own, sharing space only with the
sequence number.
*/
#define MAVLITE_MAX_PAYLOAD_LEN 31 // 7 float params + cmd_id + options
#define MAVLITE_MSG_SPORT_PACKETS_COUNT(LEN) static_cast<uint8_t>(1 + ceilf((LEN-2)/5.0f)) // number of sport packets required to transport a message with LEN payload
#define SPORT_PACKET_QUEUE_LENGTH static_cast<uint8_t>(30U*MAVLITE_MSG_SPORT_PACKETS_COUNT(MAVLITE_MAX_PAYLOAD_LEN))