PicoCalc by ClockworkPi is an amazing kit. But for my needs it lacks a few things, like how am I supposed to make a custom handheld system without RTC? Impossible… Thankfully Clockwork shares all the files on their github so it’s fairly easy to add custom boards. Another thing, have you seen its software? Don’t get me wrong, PicoMite is incredible, why would you use BASIC in 2025 though? So I’m also making new software…
But let’s not get ahead of myself. Let’s, for now, focus on hardware
Things added - hardware#
Alright, PicoCalc comes equipped with 320x320px 4-inch IPS screen, QWERTY backlit keyboard, speakers and 3.5mm audio jack and an SD card reader all powered by Raspberry Pi Pico H (yes, that’s exactly what it’s said on the website). And that’s great, It’s plenty enough for a good handheld, but for my needs it lacks:
- RTC
- Environmental sensors, this includes thermometer, hygrometer and a barometer
- IMUs, magnetometer and an accelometer-gyro combo to be exact
- Extension port for I2C devices
- High power LED (bc I can)
- WiFi and bluetooth, thankfully I can swap Pico H for Pico 2W
- And last bat not least, a place for the allen key that comes with the PicoCalc
So that’s what I did, I added all of those to my PicoCalc, lucky it has A LOT of unused space inside.
Case#
But adding that stuff is one thing, another thing is mounting them inside. And that took me 2 tries. At first I used the awesome back replacement by n602 on Thingiverse (here is a link: Replacement bottom part for PicoCalc on Thingiverse). And I have modified it heavily to fit all I wanted. Just without the LED and extension port, that idea came to my mind later. And I printed this case in my beloved turquoise PETG
But a few weeks later I had a genius idea to add an extension port developed for my other project - Otsi.mk2, high power LED as well as a mysterious port for something I will talk about in a minute. But at that point I wasn’t totally sure if I wanted to change all of it. Soldering took a long time and I wanted to just program my PicoCalc. But after finding Kelpiscool’s work on github I had to make it. Kelpiscool made an awesome modular back for PicoCalc that is much more flexible than n602’s design (here you have a link: PicoCalc modular back on Github). So I have spent a lot of time designing the new Back and finally here it is. Printed in beautiful bottle green and mat black. TBH I think it looks better than the turquoise one.
I also thought that it would be nice to show the comparison between the original back by ClockworkPi and my 2 attempts so here you have it:
Software#
The software is something special. Bc of PicoCalc being basically a glorified Raspberry Pi Pico I have been programming it in Arduino IDE (bc it’s better than micropython…). My main goals for PicoCalc OS (named Otion-OS) are:
- Displaying data from all the sensors in a convenient way
- Having a notepad
- Having google calendar and weather forecast integrated
- Can’t forget about the calculator, this includes:
- Regular calculator
- Scientific calculator
- Trigonometry calculator + pitagoras triangle calculator (I use it a lot)
- Proportion calculator (Also using it a lot)
- Unit conversion
- Wire thickness calculator
- Additionally everything that the I2C module outputs
- And something special, remember that mysterious port from earlier? That is for thermal printer, so my PicoCalc is going to be a printer as well.
And those are my plans, as of today (10.07.2025) I have made the main menu and will now proceed into making widgets (google calendar and weather forecast, those two blank rectangles). Below you have a few photos showing current progress:
Last words#
Currently I’m not sharing any files for my mods for PicoCalc, mainly bc I don’t have the time to work on all the instructions and bc it uses a lot of other people’s projects and dealing with the licenses would be a nightmare. Hope you understand. But if you want some advice or maybe even some files don’t hesitate to massage me! At last here are some photos I took while soldering the second case:
That’s all, thank you soooo much for reading all of this. Hope to see you again!
Keep dreaming and stay persistent
~Simon