On 25/10/12 12:00 Chris Green wrote:
> I'm looking for reasonably priced and reasonably easy to implement ways
> to measure voltages with a computer. To be more specific:-
>
> The computer will either be the existing eeePc running Ubuntu (but
> no GUI) or a raspberry pi.
>
> I need to monitor at least four and preferably eight or so voltages,
> some of these are 12 volts (i.e. lead acid batteries) and others are
> current transducers giving an output around 2.5 volts with a +-0.5
> volts swing.
>
> I don't need *incredible* accuracy but something around 2% or better
> is necessary for it to be useful in monitoring battery charge state.
>
> I want it to be cheap!
>
> Sample rate can be slow, once an hour would be fine.
I built myself a home power monitor using a Freescale 8-bit HCS08 series micro-controller and an
FTDI USB/serial interface chip, both powered from USB. I'm running two ADC channels @1kHz sample
rate to take differential samples from either side of a biased current detector clamp. I'm sure
something similar would be ideal for battery monitoring.
Total cost - micro-controller free - obtained as a 'sample', FTDI chip you might get a 'sample' for
free, but more likely to pay ~ £5, PCB ~ £0.50 if you use 0.1" DIP pinout devices and stripboard.
The fun bit is writing the code :)
P