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ENG-CANSAT-PICO-MISSION1-CAPTURE (voir la source)
Version du 6 mars 2022 à 13:49
, 6 mars 2022 à 13:49→About testing
{{ambox|text=The '''ACK'''nowledgement feature is disabled to avoids unnecessary latency when waiting back for ACK response (which may never comes back in the case of a CanSat in high altitude). }}
{{ambox|text=The '''ACK'''nowledgement feature is disabled to avoids unnecessary latency when waiting back for ACK response (which may never comes back in the case of a CanSat in high altitude). }}
== Structuring the data ==
The radio module only sends buffer of binary data to the receiver. This is a bit rough but efficient.
So to transport the data to the receiver, we need to transform the values (float, integer) into their string representation.
When having multiple data in their string representation is not enough, they must also been organized.
'''The final format must be easy to parse and very compact''' (smaller is the radio message and higher is the chance for him to get to the ground without error).
We propose the following format:
<nowiki>:data1|data2|data3|data4;/r/n</nowiki>
where:
* ''':''' is the begin of data stream
* ''';''' is the end of data stream
* '''/r/n''' are optional carriage return + line feed characters.<br />This will would make the messages user friendly when the the messages are viewed in a console or terminal.
* '''|''' is the separator between data items.
* '''datax''' are the string representation of the various data. The characters ;:| are forbidden in this area.
we would also recommend to use:
* '''packetnum''' as data1. packetnum is a simple variable increment of one unit after each transmission. This would allow the receiver to detect lost message (since it would exist holes in the numbering of received messages).
* '''timing_info''' as data2. This would help to create timing chart or time base data analysis. We suggest to use the Arduino's {{fname|millis()}} function which count the number of milliseconds since the last microcontroler reset.
As explained later in the code the {{fname|packet_str}} variable contains the message to be transmitted to the ground. The Arduino's {{fname|String}} class would ease the transformation of data to their string representation.
<syntaxhighlight lang="c">
String packet_str = String( ":"+String(packetnum,DEC)+"|" );
packet_str.concat( String( ms,DEC)+"|" );
packet_str.concat( String( temperature, 2 )+"|" );
packet_str.concat( String( bme_hpa, 2 )+"|" );
packet_str.concat( String( bme_temp, 2 )+";\r\n" );
</syntaxhighlight>
{{ENG-CANSAT-PICO-TRAILER}}
{{ENG-CANSAT-PICO-TRAILER}}