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GitHub Repository: Ardupilot/ardupilot
 Path: blob/master/libraries/AP_Frsky_Telem/AP_Frsky_MAVlite.h
Views: 1798
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#pragma once

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#include "AP_Frsky_Backend.h"

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/*

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  Wire Protocol:

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  Several SPort packets make up a MAVlite message.

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  A maximum of six relevant data bytes are present in an SPort packet.

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  Each SPort packet starts with a sequence number, starting with zero.

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  If the sequence number is zero then the parser is reset.

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  The first sport packet contains len at offset 1.  It is the

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  *payload* length - does not include checksum, for example.  msgid is

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  at offset 2, then payload bytes.

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  Subsequent SPort packets contain a sequence number at offset zero,

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  followed by more payload bytes.

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  When sufficient payload bytes have been received (based on "len"), a

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  single checksum byte arrives.  Sometimes this checksum byte goes

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  into an SPort packet all on its own, sharing space only with the

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  sequence number.

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*/

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#define MAVLITE_MAX_PAYLOAD_LEN                 31 // 7 float params + cmd_id + options

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#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

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#define SPORT_PACKET_QUEUE_LENGTH               static_cast<uint8_t>(30U*MAVLITE_MSG_SPORT_PACKETS_COUNT(MAVLITE_MAX_PAYLOAD_LEN))

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