If possible, it is best to use optical isolator chips, especially for
input. The hardware guys do the interfacing for me, but, for input,
they typically put an optical isolator chip and then use the 3.3 volt
on-board supply to power the output transister wired to the input. You
can do the reverse for the output. I do not have the circuit diagrams,
but I think it is pretty standard.
With this method, your inputs could be in the range of even 24 or 48
volts with no problems.
Also, if you want example code for the dio, look at the TS website for
the example code for the keypad and 2x24 lcd. This shows you how to do
mmap and access the dios used for the keypad and lcd, which you can
use as normal dio if you don't have a keypad or lcd.
There is also sample code for the on-board temperature sensor if you
purchased that option. I tried it out an it works just fine.
If you want to see code for the onboard free-running timer, go to
yahoo and search, some people posted code earlier.
And, that is a good way to locate old email messages that might be of
interest, yahoo has a very nice search feature for the email groups.
Works great.
Don.
On 4/17/06, robo_pigeon <> wrote:
> Hello again,
>
> Hopefully I don't irritate anyone with these "newbie" questions (is
> there a FAQ I should check?), but I really want to cover all basis
> before putting my new ts7260 to work.
>
> This question has to do with interfacing the 3.3V DIO lines to
> external circuits. How do you folks usually do this? When using a
> line for output, I'm assuming it is okay to feed directly to TTL or
> CMOS ICs (even if they have 5V Vcc) since 3.3V is logic HIGH for
> TTL. Are there any precautions (current requirements for TTL inputs,
> etc.) I need to be aware of? I'm entertaining the use of buffers as
> an extra precaution... The last thing I want to do is burn out my
> SBC.
>
> When using DIO lines for inputs, what is the recommendation there?
> Should I use CMOS buffers (with TTL inputs) running at 3.3V Vcc? Is
> it really the voltage that's the issue, or the current? In other
> words, if I place a resistor between a TTL output and the DIO line,
> will that do the trick? I rather not over complicate things, but I'm
> sure there are many good ways to interface a 3.3V IO with 5V or even
> 12V IO.
>
> Thanks for any suggestions / tips!
>
> Mike
>
>
>
>
>
>
>
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Dr. Don W. Carr
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