You might look into using the Capture module on the controller.
This would allow you to get high resolution timing from an input
signal using the internal clocks. I had a quick look at the MSP
spec and tmote pinouts and (as usual) can't make any sense of
what I'm seeing, but there may be a way to get to the input pin
you need...

Otherwise you probably need to make your own Timer interrupt
based on the internal clock and sample whatever input pin you
can connect to as a Digital I/O.

I don't know what Timers are used in the telosb/tmote TOS code
so some code archeology is probably required to start with.

MS


Jose Araujo wrote:
> Dear All,
> 
> I want to read an encoder that is connected to a motor rotating at a maximum
> speed of 4000RPM. I made the calculations and for a 4000RPM motor with a
> 1024 CountsPerRevolution encoder resolution I would need 68KHz frequency to
> be able to read the speed of the motor.
> Assuming this is right and that I would have the external 32KHz oscillator
> on my tmote sky, I would like to know if it would be possible to use the
> internal 8MHz oscillator, or if I need to place a higher external frequency
> oscillator. If I would place an external one, what would I need to change in
> terms of software? 
> 
> Thank you for the help,
> Jose Araujo
> 
> 
> 
> _______________________________________________
> Tinyos-help mailing list
> [email protected]
> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
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