[Tinyos-help] CCA Check in application layer.

[Hui Kang]

Dear All:
In my tinyos-2.x application, I would like to check the channel before 
sending a packet. By copying the following code from CC2420TransmitP.nc, 
I found the congest is always set as TRUE even I have only one mote turn 
on. Could anyone help to solve this problem or any other smarter way to 
check CCA? Thanks.

uint8_t status;
bool congestion = TRUE;
     
atomic{
            call CSN.clr();

        status = call STXONCCA.strobe();
        if ( !( status & CC2420_STATUS_TX_ACTIVE ) ) {
            status = call SNOP.strobe();
          if ( status & CC2420_STATUS_TX_ACTIVE ) {
              congestion = FALSE;
          }
        }
        call CSN.set();
}

- Hui