C64 - Connecting devices safely to the user port - Arduino data transfer

[@michaelcarey]

I blew up more than one 6526 CIA chips experimenting with my C64's User Port in the 1980s. My greatest creation was a wheeled turtle style robot with feelers that enabled it to navigate around by touch. It had LED eyes that could be programmed to blink. I found out the hard way if you accidentally ground one of the I/O pins when it's configured to be an output the 6526 becomes very unhappy.

[@c64customs]

Yes, the CIA is very sensitive and it is a bit tricky to estimate the current state of the I/O pins. I might change my setup as well since the state of the Arduino I/O pins is undefined during boot, which may cause some troubles as well. Your turtle project sounds interesting, do you have something online about it?

[@michaelcarey]

@@c64customs Sadly no, I've got no pictures of it or the interface at all. I still have the motors and the blue translucent acrylic "turtle" dome I made at school. I've got my original hand drawn schematics around the place somewhere and I still have the software I wrote to drive it. I've been thinking of recreating it with a modern commercially available wheeled robot platform with a wireless link between the robot and the interface. The original had an 9-way umbilical cable.

[@TheHighlander71]

I probably wouldn't have thought of the differences between the ground and 5v levels. I made a megadrive controller converter once using arduino which was a fun project. But the rabbithole goes deep!

[@c64customs]

Yes, it's a tricky topic :) The Sega controllers working with high active signals and the CIA of the C64 doesn't like to get 5 V from the outside so using a converter is highly recommended. Thanks for mentioning it.

[@TheHighlander71]

@@c64customs Oh should have said. It's a converter from the classic 9 pin connector to usb, so I can use a classic megadrive controller on a megadrive mini. For once it had nothing to do with the C64 :)

[@rafaelmmartinez9170]

Did you make the fancy USerport Protobard connector? Really cool

[@tenminutetokyo2643]

Happy new year dood!

[@c64customs]

Same for you, thanks mate!

[@adamt3912]

Very interesting post.Agree, the user port is really not well explored.Thanks, some good information.I have a HomeAssistant set up in my home for automation and I am always looking at new integrations. I can see simple integration with MQTT but also some more detailed text based messaging based on this. Perhaps pretty pointless but very cool in an old skool way!

[@c64customs]

jepp, it looks like we do a lot of pointless things but I'm strangely attracted by such topics ;)

[@adamt3912]

@@c64customs Hey..you are just proving I am not alone. I already have a need to get a phone notification via my home automation hub whenever the C64 is powered on and another saying "Now playing"....this post could lead to full on messaging! Who doesn't want that?!

[@CiociariaStorica]

Interesting link between c64 and Arduino. In the last part of the video, does the data received by the Arduino come from the program in the c64?

[@c64customs]

yes, indeed, that was the main purpose, sorry for not covering this well enough :)

[@CiociariaStorica]

@@c64customs Ok. The doubt was only for not having seen the program running on 64. Thanks so much 👍🏻🙂

[@c64customs]

@@CiociariaStorica yes, it is shown here kzbin.info/www/bejne/bp-Qi3WDnbaDpNE :)

[@CiociariaStorica]

@@c64customs My mistake, I skipped those few seconds of typing RUN 😞😳🙈😅

[@c64customs]

@@CiociariaStorica no problem :)

[@SIDCIAVIC]

Every time the parallel port is written to or read from, PC\ goes low for one cycle. This frees up PA2 for other uses,

[@c64customs]

Thanks a lot for the info, very interesting! You've got a nice nickname btw

[@SIDCIAVIC]

@@c64customs Thanks! I have been aiming to do similar things with Arduino and c64 and it is great to see someone accomplishing these intermediate steps. I still need more time devoted to Arduino programming.