Re: roZetta Status

["Alan Vogel" <avogel2@xxxxxxxxxxxxx>]

I'm not sure why optoisolators are necessary here.  All uPs that I'm aware
of have proection diodes on all of their inputs.  However, these diodes are
not beefy in terms of current handling capability.  As long as the current
is limited to 40uA or so through a resistor, it should be no problem.

Alan Vogel

"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
news:44fc6742.2111965359@xxxxxxxxxxxxxxxx
>I don't know. The ZX-40 (nee Atmel ATMega32 AVR) and most current PICs have
> protection diodes on input pins so I was looking to save a PL513 or TW523.
>
> I believe I asked whether the JDS controllers could deal with it or
> whether
> optos were needed and he emphatically opted for optos as a general
> precaution.
>
> "Alan Vogel" <avogel2@xxxxxxxxxxxxx> wrote:
>
>>Just curious,
>>
>>What was the issue using the 12VAC xfmr?
>>
>>Alan Vogel
>>
>>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>>news:44f43f7d.1577502015@xxxxxxxxxxxxxxxx
>>
>>snip
>>
>>>  Jeff Stein at JDS reacted in horror (well not really) when I
>>> suggested using a 12VAC transformer to supply ZC so optos are required
>>> between any of the controllers and the TTL port. I've designed circuits
>>> for
>>> both that are easily built on a general purpose board I've designed.
>>
>