Wasid, You probably can't reduce that, at least not without digging deep into the radio stack code.
Notice that there is a significant delay between issuing send and the packet actually going out. First, the SPI resource needs to be acquired. Then, the packet is uploaded to the TX FIFO of the radio chip. The SPI clock rate is 256kbps, so it takes more time to upload a packet to the radio chip than to actually transmit it! After the packet is uploaded to the FIFO, the backoff timer is started. No matter if you set the initial backoff to 0, it will take some time till the timer is fired. Then, the CCA is carried out, and if the channel is clear, the send strobe is issued. That's when the radio chip starts sending the preamble. If acknowledgements are off, the sendDone event is signaled from a task which was posted from the interrupt context that was triggered by the SFD pin going low after the last byte of the packet is transmitted. If acknowledgements are on, there are further delays: the driver waits for the ack to arrive (or timeouts), and the sendDone event is signaled only after that. To sum it up, this clearly takes several tens of milliseconds. The question is, why do you want to reduce this time? What do you want to achieve and why? Janos On Thu, Feb 7, 2013 at 8:02 AM, wasif masood <rwmas...@gmail.com> wrote: > > Hi All, > > I know this is probably an old topic but I still couldn't find any solution > to that. Well, I am using CC2420Transmit.Send interface which is connected > to CC2420TransmitC. Even at this lowest level of wiring the time elapsed > between the Send and SendDone signal is in 10's of milliseconds (I have > tested it for both Z1 and TelosB). Is there any way I can reduce this time? > Please share your expertise! > > Regards, > Wasif Masood > > _______________________________________________ > 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
