On Fri, Oct 9, 2009 at 11:25 AM, Harold Hallikainen
<harold@hallikainen.org> wrote:
> Slight topic drift here... The need for the cheap isolated DC to DC
> converter is typically to drive transmit/receive circuitry on an isolated
> power supply to avoid ground loops.
>
> I've got a situation where I need to sense maybe 24 contact closures to
> "ground" and drive about 24 open drain outputs. The sense and drive
> circuitry needs to be on an isolated supply to avoid a ground loop with
> the equipment that is driving it (referenced to its ground). It seems like
> the simplest way to get data back and forth is to use a UART in a PIC on
> the floating side and two opto-couplers, one in each direction to talk to
> a UART on the nonfloating side.
>
> Any ideas for something simpler?
>
> Harold
>
>

If you can spend the time on extra firmware and you can deal with the
latency, it sounds like a reasonable plan. I'd at least consider the
dumb and simple option of having a pile of optocouplers.

It seems like it would be a few dollars cheaper in hardware to have 1
pair of optos and a $1 PIC, but again firmware usually costs money.

--
Martin K.
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