Hi,
Problem:
I have 13 0-5V 'stepped' signals that will have four voltage levels at Vss, 1/3*(Vdd-Vss), 2/3*(Vdd-Vss) and Vdd. I'd like to sample at 1kHz (Nyquist's Theorem) and essentially end up with a 2 bit value for each signal.
I've thought about doing it onboard with a PIC 18F4520 (just because it's the one I'm most familiar with), but the high (10bit) resolution is overkill and the ADC happens sequentially meaning it would take rather a long time and wouldn't give me a comparison of the waveforms to each other at a single instance of time.
Individual ADCs are again very high in both cost (particularly important with 13 signals in total) and board space. Another option I see would be to create my own flash ADC but again cost and board space.
Would it be better to multiplex the signals by attenuating each one by specific weighted amounts and then use the PICs onboard ADC to create a 10bit value that could then be related to the signal values?
Any other suggestions? I've never had to do any ADC work before and looking on RS Components it doesn't strike me that there's a suitable chip....
Cheers,
Problem:
I have 13 0-5V 'stepped' signals that will have four voltage levels at Vss, 1/3*(Vdd-Vss), 2/3*(Vdd-Vss) and Vdd. I'd like to sample at 1kHz (Nyquist's Theorem) and essentially end up with a 2 bit value for each signal.
I've thought about doing it onboard with a PIC 18F4520 (just because it's the one I'm most familiar with), but the high (10bit) resolution is overkill and the ADC happens sequentially meaning it would take rather a long time and wouldn't give me a comparison of the waveforms to each other at a single instance of time.
Individual ADCs are again very high in both cost (particularly important with 13 signals in total) and board space. Another option I see would be to create my own flash ADC but again cost and board space.
Would it be better to multiplex the signals by attenuating each one by specific weighted amounts and then use the PICs onboard ADC to create a 10bit value that could then be related to the signal values?
Any other suggestions? I've never had to do any ADC work before and looking on RS Components it doesn't strike me that there's a suitable chip....
Cheers,