Arduino Clock Generator Shield PCB Build Guide

By Kevin on October 27, 2024

Here are the build notes for my Arduino Clock Generator Shield PCB.

Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!

If you are new to Arduino, see the Getting Started pages.

Bill of Materials

Arduino Clock Generator Shield PCB (GitHub link below)
12x BAT43 Schottky diodes
6x 470Ω resistors
3x 10nF ceramic capacitors
2x 100nF ceramic capacitors
Optional: Switched rotary encoder (see photos for footprint)
Optional: 0.96" 128x64 or 0.91" 128x32 SSD1306 I2C OLED display (pin out: GND-VCC-SCL-SDA)
Optional; 2x 4-way pin header sockets
6x stereo TRS jack sockets (see photos for footprint)
Complete set of Arduino extended headers (1x10 way, 2x8 way, 1x 6 way)

Note that extended Arduino headers are recommended as they have longer legs which ensures that the TRS sockets will not get shorted out on the Arduino's USB socket or ICSP header.

If normal Arduino headers are used then steps must be taken to remove the possibilities of shorts once plugged in.

Build Steps

Taking a typical "low to high" soldering approach, this is the suggested order of assembly:

Diodes.
Resistors.
TRS sockets.
Disc capacitors.
Arduino extended header sockets.
4-way pin header sockets (if used) or OLED displays (if directly connected).
Rotary encoder.

The shield supports either a 128x64 or 32x64 OLED display and has a 4-way pin header breakout for each with an associated 100nF capacitor. If only one variant will ever be used then only one header and capacitor would be needed.

Hopefully it goes without saying that only one OLED display should be plugged in at any one time and it should only be changed with the power off.

Here are some build photos.

The diodes then resistors are added first, followed by the TRS sockets.

Then the capacitors and finally the pin headers. It helps if you can use an existing Arduino shield to hold the shield headers in place during soldering. The 4-way headers were added last and held in place using blutack.

The encoder is added last. The photos show the two configurations of display.

Note that the display pinouts must match GND-VCC-SCL-SDA. I've seen displays with GND-VCC swapped and also displays with SCL-SDA swapped.

As I say, only one display can be used at any time.

Testing

I recommend performing the general tests described here: PCBs.

PCB Errata

There are the following issues with this PCB:

None at present.

Enhancements:

It might be possible to squeeze in a MIDI OUT connection too.
The encoder could be re-routed to use D2, D3 to allow the use of IO pin interrupts as an option.
An external clock input could be added.

Find it on GitHub here.

Sample Applications

The following Arduino GPIO pins are being used:

D2, D3, D10-D13 for the clock outputs.
D4-D6 for the encoder.
A4, A5 for the I2C display.

All unused IO pins are labelled on the board.

Here are some applications to get started with - they will need updating to the above IO use:

Arduino Euclidean Gate Sequencer – Part 2 (doesn't use encoder or display)
Arduino Euclidean Gate Sequencer - Part 3 (includes encoder and display) - on the way...

Closing Thoughts

This has turned out really neatly in the end and whilst the Uno form factor isn't the most useful, it is still pretty ubiquitous when it comes to having something as a core for further experiments.

Kevin