How did you measure the 8ms? Remember, you also have to "upload" the
message into the radio over
SPI, and "download" it from the radio. That takes time too. Oh, and
what platform and target are you using?
- Thomas
On Mon, Jul 12, 2010 at 10:28 PM, Obaid Salikeen
<obaidsalik...@gmail.com> wrote:
> Hi,
>
> I am using the most lowest component for sending i.e CC2420transmitC, and
> CC2420ReceiveC.
>
> Problem is that it is taking too long to send and receive a message with
> just 2 bytes payload and 21byte header (CC2420_SIZE).
>
> It is taking 8ms, so if a sender has send a packet, ACK will be received in
> 16ms.
>
> I thought cc2420Transmit was the lowest component, and that it should right
> away send the packet without any delay. I set the radio backoff values to 0,
> and disabled CCA, but still it takes too long. please if some body know then
> do share that why it takes so long,,,what it there between CC2420TransmitC
> and Radio that increase the transmit time ?
>
>
> The theoretical transmission delay that i calculated is 0.736 Milli second
> i.e 736micro seconds, but in reality its taking more then 8ms which is
> strange.
>
> // Tested in Java,
> int payloadLength = 2; //Example value
> int CC2420_SIZE = 21; // Example value
>
> double transmissionTimePerSecond=0;
> double transmissionTimePerMilliSecond=0;
> double totalBitsToSend = 0;
> double totalBytesToSend = payloadLength + CC2420_SIZE ;
>
> totalBitsToSend = totalBytesToSend * 8;
> //Data rate is 250KBits/sec i;e 250 000
> transmissionTimePerSecond = totalBitsToSend / 250000 ;
> transmissionTimePerMilliSecond = transmissionTimePerSecond *
> 1000; // 1000,000 for Micro Seconds.
>
> //transmissionTimePerMilliSecond gives me value of :0.736 Milli
> Seconds and 736.0 Micro Seconds,
>
>
> PS:
> async event void RadioBackoff.requestCca(message_t *msg){
> call RadioBackoff.setCca(FALSE);
> }
> async event void RadioBackoff.requestCongestionBackoff(message_t *msg){
> call RadioBackoff.setCongestionBackoff(0);
> }
> async event void RadioBackoff.requestInitialBackoff(message_t *msg){
> call RadioBackoff.setInitialBackoff(0);
> }
>
>
> _______________________________________________
> Tinyos-help mailing list
> Tinyos-help@millennium.berkeley.edu
> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>
_______________________________________________
Tinyos-help mailing list
Tinyos-help@millennium.berkeley.edu
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
