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Re: [Paparazzi-devel] Data format


From: Pascal Brisset
Subject: Re: [Paparazzi-devel] Data format
Date: Tue, 02 Dec 2008 08:02:34 +0100
User-agent: Thunderbird 2.0.0.18 (X11/20081125)

Hi,

a message contains:
- one byte for the aircraft id (from conf.xml)
- one byte for the message id (from messages.xml)
- the fields of the message, as described in messages.xml

Macros for message generation and fields access are generated from conf/messages.xml into var/include/messages.h . See also sw/include/downlink.h

In transparent mode (i.e. not the "XBEE" mode), the payload is wrapped into (see pprz_transport.h) a frame:

  |STX|length|... payload=(length-4) bytes ...|Checksum A|Checksum B|

where checksum is computed over length and payload:
     ck_A = ck_B = length
     for each byte b in payload
       ck_A += b; ck_b += ck_A

--Pascal



* space * wrote:
Hello,
I wanted to ask you about the data format traveling through the Datalink. Thanks




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