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Csma ca PLC EVALKITST7580

Question asked by jung.julian on Sep 2, 2014
Latest reply on Sep 2, 2014 by Clive One
Hello,

Currently we are working on a custom board based on the power line modem demonstration kit (EVALKITST7580).
I have question specifically regarding the firmware that we have received from ST of this evaluation board. 
We have 16 nodes that send data to the Master and a csma is needed to avoid collisions. So I need to sense the Power line before sending. 
With this check in my main application section: 
if((RxData = DL_DataIndication(SAddress, &Datalen, DInParameters))!= NULL)
    { .. }
I can only sense a non-corrupted data, so only when I received a correct frame it is true.
Now if node 1 send a packet, and in between there are 14 nodes, the node 16 (the last one) will receive a corrupted data. My question is if the firmware have the capability to sense if the power line is completely free from any signal so that I can start counting  from this point a backoff time.
Starting a backoff time only if the condition above is true, it would be wrong because it does't tell you if a corrupted data was present in the line. 
I don't know if my explanation is clear enough and if you got my point. Basically I need to find the point in the firmware where I can start the backoff time. I need to check if the node have received any frame (whether corrupted or not)
Your help would be very appreciated.
Thank you
- J.J

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