On Apr 7, 2007, at 2:20 PM, Boris Lipchin wrote:
Hi,
I'm working with a TMote Sky, and I'm trying to get the ADXL330
accelerometer hooked up. According to the slau049f datasheet for
the MSP430 (the tmote sky microcontroller), the on board 12 bit ADC
has a number of conversion modes. These are Single-channel-single-
conversion, sequence-of-channels, repeat-single-channel, and repeat
sequence-of-channels.
I got the accelerometer interfaced to the ADC via the following
instructions on the website: http://www.moteiv.com/community/
Connecting_External_Sensors. However, this binds a single analog
port to the ADC, and this seems to be the single-channel-single-
conversion mode. In order to get it working I had to put a
semaphore-like block around the getData call to my three ADC
interfaces, sort of like a sendMsg call (i.e. you can only be
converting X, Y, or Z axis port at one time). This works, but is a
bit sluggish. For the three axis accelerometer I would prefer the
ADC to continuously translate the voltage on the x, y, and z ports.
This sounds like the repeat sequence-of-channels mode. I haven't
found any tinyOS documentation that talks about the ADC in depth to
touch on different conversion modes. My code is very similar to the
code on the website above.
I was wondering if tinyOS 2.x had anything in place to support
other ADC conversion modes.
The best person to ask would be Jan Heinrich-Hauer, who wrote the
MSP430 ADC system; I think TEP 101 goes into some details. I'm not
that familiar with all of the details. There is an interface that
sounds promising, though, Msp430Adc12MultiChannel:
http://tinyos.cvs.sourceforge.net/tinyos/tinyos-2.x/tos/chips/msp430/
adc12/Msp430Adc12MultiChannel.nc?revision=1.2&view=markup
Phil
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