Rotary Encoder missing VCC pin in diagram

[hjnijlunsing]

Hi I just built the Throttle Blaster with the rotary encoder; works great!
On my Pentium III / 450mhz I am able to play Monkey Island I, Space Quest 3 and Ultima 6.
Haven't got Bubble Bobble to work but I'll see if I can play around some more.

When building I noticed that in the diagram to the rotary encoder I was missing the VCC (5V) and the Ground seems to be mentioned twice.
I connected the Ground to Ground, VCC to 5V and Key to the Switch PIN and it was working correctly.

Another thing to mention; I am using a SLOT-3 Pentium 3 CPU;
In my experience it is far more easier to take a thin wire and put in the SLOT directly instead of soldering it to the CPU.
So, take the CPU out; put the thin wire in the tiny hole on the SLOT-3 and put the CPU back in which will "lock" the wire into place.

Thanks for your work!

[scrapcomputing]

Nice! Good to see that you had some success with it :)

The schematic is right. The rotary encoder is only connected to ground. The GPIO pins have a weak pull-up so the rotary encoder will pull them down to ground as it moves. Don't connect the rotary encoder to 5V, it may damage your Pico.

I haven't tried sticking a wire into the slot directly, thanks for sharing!

[hjnijlunsing]

I just tried connecting the VCCpin from the encoder to the Ground, but then the Throttle Blaster stops working and doing random stuff on the display ;-)

Back to 5V and it starts working again. Perhaps I am using another rotary encoder?

My pins are labelled:

• GND
• S1
• S2
• KEY
• VCC

Do you think it could still harm the Pico? My guess is that my rotary encoder requires the 5V to work.

My Bubble Bobble issue is not related to the throttle blaster; it seems that this is one of the few games which refuses to work with the ESS SOLO-1. ;-) Time to buy a PicoGus probably...

[hjnijlunsing]

This is the link: https://nl.aliexpress.com/item/1005001696915804.html

[scrapcomputing]

Hmm the encoder in the link you shared has some circuit board on it, not sure what that does. The Throttle blaster is designed to work with a standalone encoder without any circuit board.

5V may damage the pico's GPIOs. Try supplying 3.3V from pin 36 instead.

[hjnijlunsing]

Thanks! Connecting to the 3.3V also seems to work; although on better inspection the rotary encoder states 5V and not VCC as I previously thought ;-).
Though I'll keep it connected to the 3.3V instead.

Next I am going to add the MAX232; but also here I have a board which already has the chip on the breakout board. (https://nl.aliexpress.com/item/1005006220311651.html) thus I am guessing I can connect that directly to the PICO to the related pins.

Again thanks for the great work!

[scrapcomputing]

You need to use a MAX3232, a MAX232 won't work since it's a 5V part.
Also keep in mind that most of the cheap MAX3232/MAX232 modules on breakout boards use fake chips that don't work at all, or work for a few seconds and stop working after that. So don't worry if you can't get it to work, it's most probably the chip that's bad.

[hjnijlunsing]

You were right, it was actually a MAX3232 chip, and it does seem to work ;-)

Though sometimes I have to execute it twice; in that case the first time it will dispay (UART) and then revert to the previous setting. I am using Dos Kermit like the documentation.

Any thoughts on this? Bad UART chip? In any case; I'll put it in my batch commands twice then it will be ok ;-)

[scrapcomputing]

I would bet it's the chip. I have tried both (i) modules and (ii) individual clone chips and both were faulty. Some of them would work somewhat, others wouldn't work at all. MAX232/3232 clones are notoriously bad. These modules are pretty handy though, so you could try replacing the chip with a decent one from a known manufacturer like Texas Instruments. Surface-mount MAX3232 compatible ICs from known manufacturers are widely available and not too pricey.