Step-sequencer monosynth build

Using Arduino Audio
1

Hello Arduino forum,

here's my latest project, a step-sequencer monosynth called Arpeg4.

There was a dev thread in 2018 : A few questions about a programmable step sequencer

But until now I got it in an enclosure with potentiometers, a start/stop-switch and unbalanced 6,3mm output jack. I'm looking to add CV/Gate out.

I had to Google around for some code solutions such as reversing the tempo pot.

Here's the schematic :

640×601 32.3 KB

And the code :

void setup() {
  Serial.begin(9600) ;
  pinMode (A0, INPUT) ;
  pinMode (A1, INPUT) ;
  pinMode (A2, INPUT) ;
  pinMode (A3, INPUT) ;
  pinMode (A4, INPUT) ;
  pinMode (12, INPUT) ;
  pinMode (13, OUTPUT) ;
}

void loop() {
  int tempo = 1023 - analogRead (A4) / 4 ;
  int noteLength = 100 ;
  int step1 = analogRead (A0) / 8 ;
  int step2 = analogRead (A1) / 8 ;
  int step3 = analogRead (A2) / 8 ;
  int step4 = analogRead (A3) / 8 ;
  Serial.println (digitalRead(12)) ;
  
    if (digitalRead (12) == 1) {

   tone(13, step1, noteLength);
    delay(tempo);
   tone (13, step2, noteLength);
    delay(tempo);
  tone(13, step3, noteLength);
    delay(tempo);
   tone(13, step4, noteLength);
    delay(tempo);
}
else {
  noTone(13) ;
  }
}

That's about it. I noticed there's an Uno synth kit available, is it any good?

I'd figure most would want 3,5mm CV/Gate outputs, this is very simple; an analogWrite on a pin for the step CV and a digitalWrite for the gate.

Have a nice midsummer,

-ef

2

It looks like you have wired the potentiometers strangely! Usually, we connect one end terminal to ground as you show. Then we connect the other end terminal to the voltage source. Then we take the variable voltage from the center, wiper, terminal.

3

Hi, @efinque

What you potentiometer configuration does is SHORT the 5V from the Arduino when the wiper is moved to the gnd end of the pot.

image
image1316×391 41.9 KB

This is better and will not overload your Arduino.

image
image1337×404 41.3 KB

Can you please post some images of the inside wiring of your project?

Tom.. :smiley: :+1: :coffee: :australia:

4

Here's a pic of the insides :

359×640 52.7 KB

As you can see I used terminal blocks for the power distribution and the ground bus which is sort of crude but it works.

5

Hi, @efinque
Your image shows the same error of connection.
The wiper should not be connected to the 5V supply.
Your potentiometer terminals are;
image

Can you see where the danger of shorting your Uno output is?

Look at what happens when you turn the wiper to minimum.

Do you have a DMM? Digital MultiMeter?

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

Tom.. :smiley: :+1: :coffee: :australia:

6

Yeah I noticed that when the pots are all the way to CCW and the ground bus is plugged in the Arduino shuts itself off.

Maybe a pull-up resistor would help?

7

No, you need to re-wire the pots as in post #3.

image
image1337×404 41.3 KB

Do you have a DMM? Digital MultiMeter?

The UNO is not turning itself OFF, you are shorting the power supply.
What is your power supply?

Tom... :smiley: :+1: :coffee: :coffee: :coffee: :coffee: :australia:

8

I'll try rewiring the potentiometers.. and I do have a DMM, an Uni-T iirc.

The breadboarded version worked just fine, so does this.

EDIT : oh, and it's powered via the 5V pin