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Re: Going to use gpio for the first time

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The Natural Philosopher <tnp@invalid.invalid> wrote:
> On 22/04/2026 21:09, druck wrote:
>> On 22/04/2026 20:40, The Natural Philosopher wrote:
>>> On 22/04/2026 17:08, Michael Schwingen wrote:
>>>> On 2026-04-21, Daniel <me@sc1f1dan.com> wrote:
>>>>> Are there any newbie things I should look out for while I dive in?
>>>>> I'll be doing all the work on my trusty stock pi500.
>>>>
>>>> Be careful about different voltage levels. The atmega *can* run on 
>>>> 5V, while
>>>> the raspberry's GPIO pins only tolerate 3.3V.
>>>>
>>> In theory., In practice they can tolerate 5V if not from an uber low 
>>> impedance source
>> 
>> To avoid tears before bedtime, it is best to disregarded that.
> 
> *shrug.* been running that way for some time

It'll have protection diodes that limit the voltage at the inputs
to less than the 3.3V supply. However they're not designed to be
used in normal operation so the extra current carried from them
on the power connections inside the chip might upset the voltage
to other parts and cause weird problems, eg. when lots of inputs
go to 5v. So it could be a source of very confusing behaviour and
possible damage, though it's probably a small risk if there are
just a few high-impedance 5V signals connected.

-- 
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Going to use gpio for the first time Daniel <me@sc1f1dan.com> - 2026-04-21 09:53 -0700
  Re: Going to use gpio for the first time rbowman <bowman@montana.com> - 2026-04-22 00:54 +0000
    Re: Going to use gpio for the first time Daniel <me@sc1f1dan.com> - 2026-04-22 07:09 -0700
  Re: Going to use gpio for the first time Michael Schwingen <news-1513678000@discworld.dascon.de> - 2026-04-22 16:08 +0000
    Re: Going to use gpio for the first time The Natural Philosopher <tnp@invalid.invalid> - 2026-04-22 20:40 +0100
      Re: Going to use gpio for the first time druck <news@druck.org.uk> - 2026-04-22 21:09 +0100
        Re: Going to use gpio for the first time The Natural Philosopher <tnp@invalid.invalid> - 2026-04-22 21:13 +0100
          Re: Going to use gpio for the first time Theo <theom+news@chiark.greenend.org.uk> - 2026-04-22 23:45 +0100
            Re: Going to use gpio for the first time The Natural Philosopher <tnp@invalid.invalid> - 2026-04-23 09:58 +0100
          Re: Going to use gpio for the first time not@telling.you.invalid (Computer Nerd Kev) - 2026-04-25 08:33 +1000
    Re: Going to use gpio for the first time Daniel <me@sc1f1dan.com> - 2026-04-22 23:55 -0700
      Re: Going to use gpio for the first time rbowman <bowman@montana.com> - 2026-04-23 18:35 +0000
  Re: Going to use gpio for the first time Gordon Henderson <gordon+usenet@drogon.net> - 2026-04-23 12:36 +0000

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