The Screwduino Story

A Screwduino is an Arduino UNO compatible with Screw Terminals.

We find most of the approaches to Arduino breadboarding annoying. They work OK if you don't know what you want to make and you just want to mess around, but they are painful when you are ready to really make something useful.

We have spent countless hours soldering simple interconnect wires on prototype shields. They give us exactly what we need/want but why do we have to spend time soldering in yet another connector that doesn't do much more than pinout another connector?

Sensor shields are a pretty decent solution since they pin out everything with a power and ground for each signal, but they can get pretty pricey when you add in the cost of the shield and cabling. Plus they get pretty tall till you have a Processor, Sensor Shield and then the vertical wiring above all that.

Then, we saw a screw shield and it looked like the ideal solution for loose wires and builder frustrations. Easy to connect with just a small screwdriver. No connectors to install for simple wiring but no accommodation for I2C connections. The stackup height has less of the same height problems as a sensor shield. The screw shields got me thinking. It's a great idea, but why add the shield? Why not just take an Arduino design and replace the headers/pins with screw terminals?

Here is the result which we call the Screwduino:

In character, in manner, in style, in all things, the supreme excellence is simplicity. - Henry Wadsworth


  • Arduino UNO compatible
    • Arduino UNO bootloader
    • Select UNO in Arduino IDE to download card
  • No USB connector/chip.
  • ICSP header for download
  • 4-pin I2C connector for easy attachment of an I2C LCD display and other I2C sensors (like temperature sensors).
    • Beware there are many different I2C pinouts.
    • Added 10K ohm pullup resistors (R3 and R4) from the I2C SDA/SCL to +5V
    • If the user doesn't want the resistors, they can snip them out of the circuit
  • Uses through hole parts so that it is easier to assemble.
    • The sole exception is the voltage regulator which is surface mount for heat transfer
  • 5mm pitch screw terminal blocks.
  • Reset switch.
  • 7-12V DC on standard 2.1mm DC power connector
  • Power selection jumper (FTDI, Regulator, Screw Terminals)
  • Four (4) good mounting holes that could 4-40 screws and have more than enough clearance for screw heads, standoffs and/or nuts.