Path: csiph.com!weretis.net!feeder8.news.weretis.net!npeer.as286.net!npeer-ng0.as286.net!peer05.ams1!peer.ams1.xlned.com!news.xlned.com!peer02.iad!feed-me.highwinds-media.com!news.highwinds-media.com!fx07.iad.POSTED!not-for-mail From: Daniel Newsgroups: comp.sys.raspberry-pi Subject: Re: Going to use gpio for the first time References: <877bq02r1o.fsf@rpi3> Message-ID: <87mryu2mix.fsf@rpi3> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) Cancel-Lock: sha1:4pGHNTcWmdLKltAg0BBSr68gGFU= MIME-Version: 1.0 Content-Type: text/plain Lines: 33 X-Complaints-To: abuse(at)newshosting.com NNTP-Posting-Date: Thu, 23 Apr 2026 06:55:53 UTC Organization: Newshosting.com - Highest quality at a great price! www.newshosting.com Date: Wed, 22 Apr 2026 23:55:50 -0700 X-Received-Bytes: 2148 Xref: csiph.com comp.sys.raspberry-pi:37936 Michael Schwingen writes: > On 2026-04-21, Daniel 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. > > If you run the atmega from 3.3V too (ideally sourced from the pi, so they > come up at the same time), you have fewer problems. Still haven't initiated planning or coding yet. It's a crazy sports time for me with basketball playoffs and regular season baseball in full swing. Off the top of my head I don't intend on using gpio power. I figure the atmega could be powered by the bench power supply. The data line could get a diode, now that you mention the risk of voltage backfeed to gpio. That, or disconnect the wire between programming steps. And connect atmega and breadboard ground to gpio ground. Lacking an EE degree, learning all this magic has been a blast. Of course, that's just off the top of my head. The pi500 has a different pinout from other rpi models based on the few bits I've seen in the pdf guide. I have the gpio extender being shipped and the pinout guide thingamabob for reference. -- Daniel sysop | air & wave bbs finger | calcmandan@bbs.erb.pw