Hi there. Ive been working on a project converting an old manual espresso machine to a fully auto-matic machine. I have all of the hardware and software to a point that im happy with. i have used a raspberry Pi pico connected to a picodev oled ssd1306 oled, via a Picodev expansion board, using the Picodec cable. I am at the point where i need to tidy the hardware up and reduce its footprint. Can i cut the cable at the expansion board end and connect it to the pico via the gpio pins without having to change or update any on the code?
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I have no idea about cutting that cable but I really want to see some photos of the completed machine 
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Hi @Christian134891, Welcome to the Forums!!!
I think we all would be really keen to see pictures of this project. It sounds really interesting.
As for cutting the cable and connecting directly to the Pico. this shouldn’t be a problem. Just want to make sure the SDA, SCL, Ground and 3.3V to the correct pins on the Pi.
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Thanks for your interest Aaron. Thanks for your help too. You were spot on. This started out as a Covid project that has been put on the back burner a couple of times. I have an older Rancillio S26 coffee machine that has been a good reliable machine for about 10 years. It is an older small commercial machine from the early 90’s?? I never liked the look of it and always wanted to make it look newer. Ive stripped all the dated alloy exterior and used Aluminium core panel to give it new skin.
The way it was you switched the pump on to start the shot and turned the switch of to stop it. Which really was fine, but three big black switches were pretty ugly.
So…Ive used a Pico connected to a 8 channel solid state relay. Ive added 4 switches and an OLED display per coffee group head(x2)
switch 1- turn on group head pump
switch 2- Turn on group head pump for 30 seconds, time can be adjusted via a trim pot
switch 3- Turn on group head pump for twice as long as switch 2
switch 4- Turn off group head pump
The display shows the Rancillio logo when idle and when pouring a shot shows an animation of a drip of coffee. It looks really cool.
Total cost has been around $100. This is the first project that ive done like this, and the first time ive looked at programming in about 30 years. i thinks its going to be an ongoing thing. Once finished i plan on combining a scale that shuts the pump off when the shot reaches a certain weight.
i couldnt figure how to upload images or video but happy to share.
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Gifs work
Youtube links work too.
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Here is what i have so far.
Still got a fair bit to do. I will need to relocate the Picos to a cooler dryer place. Can anyone tell me how close to the switches and screens they need to be? Only one switch will return 3v back to the pico at a time, if that makes a difference. Is there a max size wire i should use?
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Hey Christian,
This looks awesome! I wish my wiring looked this neat. I had a look around to see if someone had an answer on how long the wires can be before you start to encounter issues. this forum post seemed pretty useful and from the testing done there 20m seems to be the minimum distance that issues started occurring over long cables. looking at your coffee machine I doubt you would need to move the Pico more than a meter or so away to keep it safe so you should be fine for the switches.
The OLED display may give you some issues however. From what I can gather information transfer over I2C starts to break down over a much shorter distance which is the protocol I assume this screen is using.
People start to report artefacts displaying in screens like this at lengths over 50cm so some testing may be required. There are ways around this though like slowing down the data transfer speed so you should be able to get it to work.
Hope this helps!
Sam
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Thanks for the reply Sam. It was a massive mess before i spent a few hours tidying it up. Now i have to mess it all up again. Part of the fun. Im using the pico 50 cm picodev cables for the screen and they seem ok. I really need to extend one of them by about 20cm. Its a pretty simple animation so slowing down the data transfer will be something new to learn. I plan on spending the next few weeks finalising the physical side of the machine. Its great having this forum for help
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id love to decorate it with some core electronics stickers 
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Hey Christian,
Its hard to know if that extra 20cm may be the difference between a perfectly working screen and a potential issue. I wouldn’t expect it to be anything drastic if it did cause you problems, maybe a slight stutter in the animation every now and again.
Given its just a cable maybe you could do some testing and let me know when you start to see issues?
As for the stickers I may be able to get a few extra tucked into your next order if you leave us a note when you place it. 
