On Saturday 30 June 2007 09:40:41 am Coalton Bennett wrote: > Greetings All, > I am working on a project that requires the coupling of an > external sensor with the Tmote Mini. The output of the > external sensor is an analog voltage waveform (AC), with > voltage amplitudes between 0 and 2 volts(AC). My objective is > to sample this waveform using the ADC onboard the Tmote mini > and wirelessly transmit this information to the Tmote Sky > connected to the PC via USB port. Once this information has > been transmitted to the Tmote Sky using the DAC I would like > to try to reconstruct the original (AC) voltage waveform. > Does anyone have any suggestions or recommendations regarding > this particular application? I would greatly appreciate any > insight that the community could provide for me.
A couple of quick thoughts. The first is radio bandwidth. If we assume the wireless network can handle ~ 100 packets per second and each packet can hold 14 ADC samples (28 byte payload max by default, 2 bytes per u16 sample), the highest continuous waveform sampling rate looks like about 1.4kHz. The second is RAM cache. Sampling at 30kHz is easily doable on msp430. The largest msp430 memory is 10KB. If you can dedicate 6KB to sample cache, it can hold 3072 samples. At 30KHz sample rate, RAM can hold about 1/10th of a second of samples. I think what you are trying to do is technically possible, but perhaps quite constrained due to available resources. Steve _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
