Hi,
I am currently working on generating an RSSI profile of a channel using a
TelosB
mote with as high a sample rate as possible. At this moment, I am only able to
obtain a new RSSI value every 155 us although the CC2420 radio provides a new
RSSI value after it has been in the receive mode for 0.128ms and for each
subsequent symbol. I have also read in another paper that the RSSI value is
obtained at a sample rate of 62.5 KHz or every 16 us but this was done on the
Tmote Sky platform. I have tried a couple of solutions but they do not seem to
work. I would like to present them here for discussion.
1. Initially, I wanted to increase the MSP430 clock rate but it has
been
previously discussed that it is only possible with the Tmote Sky as the Rosc is
not populated on the TelosB. Please refer
to
http://www.mail-archive.com/[email protected]/msg09808.html.
2. From Figure 6 in the TelosB datasheet, it shows that Timer B is
connected
with CC2420 and I assumed that it determines the clock rate of the SPI bus. If
this was true, then would it not be possible to use the SMCLK(1MHz) instead of
ACLK (32KHz) as the source for Timer B. In this way, I would be able to improve
the reading speed. I tried to ammend the source of Timer B by using TBCTL =
TBSSEL0 | MC1; in Msp430ClockP.nc but the CC2420 would not start thereafter.
What else must be done in addition? How would this affect the calibration?
3. I also tried to find out if there was a possibilty in increasing the
baud
rate of the SPI bus. After checking msp430usart.h, it seems that the fastest
configuration of ubr : 0x0002, ssel : 0x02, which means that SMCLK(1 MHz) is
already the source and that as its source and with the smallest divisor of 2.
This makes me question if modifying Timer B would help at all.
Thank you for your help and I would appreciate any advice.
Best Regards,
Tobias
.
Tobias Ang
Ruetscher Str. 165 Zi 1415
52072 Aachen
Germany
+49-1797077338
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