Introduction: MutantC V4 - Easy to Build, Modular Handheld PC

A small Handheld PC with a physical 56 key keyboard, 4inch Display and Expansion header for add-on boards (Like Arduino Shield).

Here we will discusses what you need to build one and show step by step guide. This device is very easy to make, you don't need lots of tools and parts. No codding skill is needed. just basic stuff like upload a code to Arduino, little skill in Linux CMD line to install the driver. Little soldering skill that's all.

Here is the list of features that you can get with this device,

  • Now have a Lite version that needs even less parts and easy to build.
  • Now uses ESP32-S2, so easy to solder and less loss wire.
  • 4 inch IPS display, up-to 4GB RAM, 2 HDMI out.56 key customizable keyboard, 2 shoulder button for navigation.
  • Have RTC, Buzzer, Vibration, LDR and IR Transmitter.
  • Control your home appliances using mutant's IR Transmitter.
  • Auto turn off Display when Display is covered, like when mutanC is on your pocket.
  • Supports all new & previous Add-ons, see all from HERE.
  • ThumbStick to have mouse support with left, right buttons.
  • Gyro support using MPU6050 module or Pressure or Temp and Humidity support using BME280 module.
  • Able to power off modules, Display, Add-ons using keyboard button.
  • Full power off using OS and keyboard key.
  • USB_C form-factor Nurolink/docking port with UART, I2C and Power.
  • Read battery Power level and power off the device when battery is low.
  • 2 NeoPixel, one connected to ESP32-S2 and another connected Pi.
  • 18650 battery with charge and discharge protection.
  • Improvements to casing to better fit out from the print.

Project page -

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Step 1: Equipments You Will Need

This equipment you will need to build the mutantC

  • Good soldering Iron that at lest can go 350 degrees
  • Soldering wick to remove extra solders
  • Soldering wire to solder
  • Flat head clippers to cut
  • Soldering flux.
  • Surgical knife to fix the 3D parts.
  • USB to TTL/Serial converter, 3.3v

Step 2: Be Patient and Realistic

It's a Cool and Productive project and I tried to make it as easy as possible to make it easy to build, but It can be hard to build it in some steps. Be patient and do it as the steps said, try not to go off road, this may result longer time to finish the build and misunderstanding when you ask for help.

I am here to help, i am always in this places. If you stuck or ask for some help or question feel free to do so

Step 3: Choose Your Build

You can see there is a list in the PCB, that points to some blocks. Each blocks give you one/ multipal features. So if you want a feature that you want, just solder all the parts in that block. See the build video for more explanation


Here I Made 2 version that I think fits either of you if you are a Pro or a Newbie. See this comparison table to select which one you want to build. I will highly recommend building the Lite one as it requires less parts and time to build and you will miss small number of the features. And later on you can add you can also do your own custom build by selecting the features you want on top the Lite version.

Features Lite Regular Parts List

Step 4: Order Your PCB and Print 3D Parts


There are total 5 piece of 3D printed parts, here is the link of the STL files that you need to print those parts :

You can order the Parts from the PCBway, they have excellent 3D printing service


Total 3 PCBs, go to each folder and use the file named Gerber to order the PCB.

You can directly order the PCB's from PCBway, total cost will be around $15 + shipping cost on where you live. Follow this link to order them, need to upload the Gerber files

Step 5: Solder the Parts

Solder the Parts on the those 3 PCB. Follow the build video above to build more smoothly.

You can see there are 8 blocks in the Main PCB and you should finish soldering each blocks one at a time. This helps to avoid issues and solder the whole PCB easily. You can solder the Display and Thumbstick PCB in any order.

You should follow this order to solder the Main PCB, here I am guessing you want to build the regular version of the mutantC, and you already soldered the Display and Thumbstick PCB

  • USB C Ports > S-2 > Battery connector >> Test if the battery is charging
  • S-4 (no need to solder the FPC connector for now) > top 4x2 male header >> now try to upload the firmware. See the video I attached to upload the firmware without frustration.
  • S-1 > S-3 >> Connect the battery and push the button in the S-3 module, see if it lights up
  • Solder Display FPC and 2x20 female header > S-8 >> Keyboard >> Add pi and battery and Try to hold the power button and see if pi boots
  • S-6 > S-9 > S-7 >> see all of them works in the OS by this guides

Step 6: Put All Togather

Clean all the 3D printed parts, add the threads in the case, cut the screws according to sizes, this sizes with out the screw heads as they can differ.

  • 2x 22mm
  • 6 x 6mm
  • 1 x 8mm
  • 1 x 10mm
  • 1 x 16mm

Put all the parts, try the PCB in the Case and use a sand paper to shape out where things does not fit.

Here is a video showing me doing the 3D printed parts post processing so everything fits and works well.

Step 7: Solder and Test Some Add-ons

This step is optional.

mutantC have an expansion port, it's a 2x10 female header. There are currently have 6 Add-on that can give mutantC many additional functions, like

  • Radio, Lora communication
  • Custom Wifi protocol
  • GPS
  • Micro SD for logging
  • Bluetooth
  • Pressure + Humidity + Temperature
  • Prototype, make your own circuit and use it with mutantC

Here is all the Add-ons, HERE

Step 8: Make and Do Something Using the Nurolink Port

It's a docking port when you use the mutantC dock, and also you can use it yo power or use external thing or circuit.

Here in the Picture i am testing a GPS module the is connected to the NuroLink port

You can connect 2 mutantC with each other using this port, using a USB C To USB C cable with a little modification in the cable. Just need to swap the D+ and D- lines, because TX needs to connect to RX, without the modification Tx is Connected to TX.

Nurolink has 6 Pins,

  • 2 Pins for UART/TTL, Tx and Rx
  • 2 Pins for Power, 3v and Ground
  • 2 Pins for I2c, SDL and SCL

Step 9: Troubleshot and Tips

  • Push hard one the thumbstick it to get a response if you are not getting any.
  • Waveshare lcd-C or any high speed SPI display is recommended, if you want to get the display turn off feature working
  • It's suggested to build the "Lite" edition, soldering all the "ONE" pads in the PCB, and getting it all working. Later upgrading the blocks you are interested in having (desoldering the ONE pads as needed).
  • If you want better/ longer battery life, Build the full featured version with 3.5 inch LCD and Pi 3 as these parts needs less power then a 4inch LCD and a Pi 4.
  • You might see ESP32 rebooting everytime you clciked a key. You need to connect the USB lines shown in the step 5, as esp32 does it if the usb connections are not present.
  • If your mutantC endlessly "beepbeep" that means the battery is not connected. That "beepbeep" is a low battery warning as there is no battery present/connected the system thinks the battery is criticaly low so it gives the warning.
  • Install the correct library with correct version in the Arduino IDE before building the firmware.
  • And you may see some things does not work well, like fit and finish. It's a DIY project, so you have to do a lot of post-processing to get a nice build.

Step 10: Help Me Out.

It's a Big project and complex one too. So i need all the help i can get. Please help me out if you have the Skill or ability, like

  • Arduino codding, to add feature in firmware
  • Fusion 360, to improve the supports and make it more easy to build
  • Python, to make Add-ons more useful, like a Lora based Communication App to comunicate with other mutantC users
  • FreeCAD, i want to port mutantC to freeCAD so it will be more Open Source
  • KiCAD, Same reason.

Step 11: Here Is the All the Files Related to Project

You can find schematics, STEP, Sch, Brd file and more. You can also find them in the Project Gitlab page,

mutantC Gitlab Page