[Tinyos-help] CC2420 Rssi sampling and packet reception interaction

[Philip Levis]

On Jan 24, 2008, at 2:58 PM, Octav Chipara wrote:

> Hi,
>
> I'm trying to write an application that samples the RSSI register at
> high rates and also receives packets. However, it looks like most of
> the time the you cannot access the RSSI register due to having a
> single resource manager for the entire radio. From the cc2420 manual,
> my understanding is that you could both read the RSSI register and
> receive a packet at the same time. Is this correct? If so, was anyone
> able to do this. I guess you would have to multiple resource managers
> for the radio?!
>

Software reads packets and the value of the RSSI register using a bus  
connected to the radio. So you can't read both a packet and the RSSI  
register at the same time. Therefore, you can't read the RSSI  
register at a rate faster than that determined by the time it takes  
to read a packet out.

You can always just read the RSSI register continuously and let the  
radio hardware drop packets... Note that if it's issuing hardware  
acknowledgements, then you can't read the RSSI register while it is  
in TX mode (the valid bit in the reading will be low).

Phil