This is the fourth part in a series of posts describing how I’ve approached building a “universal synthesizer panel” to house a range of microcontroller synthesis projects.
- In the first part, I detailed the general idea and overall design of the panel.
- In part 2 I built the IO panel.
- In part 3 I built the panel IO board.
- In this part I will build a microcontroller board for an Arduino Nano.
- In part 5 I will walk through the final assembly and test code for the whole thing.
- In part 6 I will port the Arduino Multi-pot Mozzi FM Synthesis to the panel and show it in action.
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
The Circuit
Recall from part 3 that I’ve specified a header format for a microcontroller board, as shown on the left above. This post describes how to build a microcontroller board featuring the Arduino Nano which fits perfectly on the 4x6cm (14×20 holes) protoboard.
Assembly
Compared to the IO board this is relatively straightforward. It is primarily a case of ensuring the right header pin is routed to the right pin on the Nano. You can use headers for your Nano if you wish, but I just soldered mine directly to the protoboard and then linked the pins up as required.
One trick it was worth noting: some of the pins I passed through “straight” into the protoboard, but some pins I bent outwards to make it easy to solder connector wires to on the top of the board. This is illustrated below (unfortunately I forgot to take a photo before fixed to the board!)
- Bent pins: D2 to D9; A0 to A3; A6, A7, 5V.
- Straight “through the hole” pins: A4, A5, RX, TX, GND (on the VIN/5V side).
Any other pins can be soldered through as required for stability, but are not necessary.
Other points to note:
- As the Arduino Nano is a 5V microcontroller, the PWR 5V header from the IO board can be directly connected to the PWR return “VCC” header to power the IO board at 5V too.
- Be sure to get A4/A5 and SDA/SCL the right way round – as shown (yellow) in the photo below.
One additional complication was being doubly sure that there were no shorts as the connecting wires either crossed or linked at angles on the bottom edge of the board.
One late addition was adding two jumper headers on the RX/TX pins to allow me to disable the MIDI link if I wanted to reprogramme the Nano in situ. If I’d thought a little more about this in advance I might have tried to incorporate a switch onto the control board, as this is quite a common thing to want to do.
But for now, jumpers it is!
Here is the completed board mounted onto the IO board prior to installing on the panel itself.
Closing Thoughts
At this point it is worth checking two things (after checking for shorts as usual):
- That the Nano still works fine, powers up and you can upload sketches as usual.
- That the Nano can be powered via the USB B connector on the IO board – although note that this will require a temporary jumper across the two 5V pins of the IO boards power connector where the link to the panel switch would be.
In the next part I’ll put it all together and create some test code for the completed module.
Kevin
Simple DIY Electronic Music Projects 