Hi, Mike.
Thanks for your help!!
Do you means that : in ram, the rssi value is stored as a negative number.
( which CC2420Packet returns)
However, in the register, the rssi value is
stored as a positive number(which CC2420Control returns)
I don't know whether my understanding is correct.
Besides, I'm curious about how the rssi value is stored in the register.
Thanks
Nathan
On Wed, Mar 24, 2010 at 2:17 AM, Chieh-Jan (Mike) Liang
<[email protected]>wrote:
> Here is my understanding. The RSSI returned by CC2420 is a negative number.
> Since CC2420Control returns an unsigned number, it needs to translate the
> raw RSSI to a positive number. On the other hand, CC2420Packet returns a
> signed number, so it can just return.
>
> Mike
>
> On Mar 23, 2010, at 4:36 AM, wx li wrote:
>
> > hi,guys.
> > I am trying to access the hardware noise floor with tinyos-2.x
> > I am confused about the code in Module "CC2420ControlP.nc"
> >
> > event void RssiResource.granted() {
> > uint16_t data;
> > call CSN.clr();
> > call RSSI.read(&data);
> > call CSN.set();
> >
> > call RssiResource.release();
> > data += 0x7f;
> > data &= 0x00ff;
> > signal ReadRssi.readDone(SUCCESS, data);
> > }
> >
> > Here, i don't know why the var data should be added by 0x7F
> > And, in Module "CC2420PacketC.nc"
> >
> > async command int8_t CC2420Packet.getRssi( message_t* p_msg ) {
> > return (call CC2420PacketBody.getMetadata( p_msg ))->rssi;
> > }
> >
> > Here, it just read the rssi value in metadata, and do not plus 0x7f
> > I've been searching for the answer for a couple of hours. But without
> luck yet..
> > Thank you for all your help!
> >
> > Regard,
> > Nathan
> > 3.23.2010
> >
> > _______________________________________________
> > Tinyos-help mailing list
> > [email protected]
> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>
>
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