Pots and switches to midi data

This schematic and program has been tested and found working.

I am sure that the code can be optimised quite a bit further.

This post is in response to a number of comments by an anonymous user in regards to an earlier example of using the Arduino to output continuous controller MIDI data (see here).

In this example, eight pots and eight switches are read and sent as various MIDI controller numbers.


Schematic
This circuit uses a 4051 to multiplex the pots and a 4021 to shift in the switch states.
Notes:

• The value of R17 should be 220Ω
• The value of R1 - R8 should be somewhere between 4kΩ and 20kΩ. I have used 20kΩ 0.25W 5% resistors in the photo examples.
  
• Jumpers JP1 represent Arduino digital pins 11, 10 and 12
• Jumpers JP2 represent Arduino digital pins 4, 3 and 2
• Jumpers JP3 represent Arduino 5V and TX pins (see here for an example of connecting the Arduino to a MIDI connection).
  
• Jumpers JP5 represent the MIDI connection (see here for an example of connecting the Arduino to a MIDI connection)
• Jumper JP4 represents Arduino analog input pin 0

Breadboard Example

The breadboard with the Arduino.

The pots and the 4051.

The 8 x SPST DIP switch and the 4021.

Arduino Code
The sketch will only send data for a given pot / switch if that controllers state has changed since the last loop. This saves any unnecessary MIDI data from being sent.

Important Variables:

• status_byte (default: 176)
  This sets the fact that it is controller data that is being sent. Values from 176 to 191 sets the channel from 1 to 16. Each control shares the same status byte (and therefore is sent using the same channel).
  
  
• cc_on_byte (default: 127)
  This sets the value of a switch when that switch is high / pressed. This value is the same for all eight switches.
  
  
• cc_off_byte (default: 0)
  This sets the value of a switch when that switch is low / depressed. This value is the same for all eight switches.
  
  
• ana_cc[] (default: {20, 21, 22, 23, 24, 25, 26, 27})
  This array sets the controller numbers for the pots 1 to 8
  
  
• dig_cc[] (default: {28, 29, 30, 31, 32, 33, 34, 35})
  This array sets the controller numbers for the switches 1 to 8

/*
Digital and Analog Data to MIDI Output
by Sebastian Tomczak


*/

byte status_byte = 176;
// control change on channel 1

byte cc_on_byte = 127;
// data to send if button is pressed

byte cc_off_byte = 0;
// data to send if button is depressed

byte ana_cc[] = {
20, 21, 22, 23, 24, 25, 26, 27}
; // set controller numbers for the pots

byte dig_cc[] = {
28, 29, 30, 31, 32, 33, 34, 35}
; // set controller numbers for the switches

byte data_ana_cc[] = {
255, 255, 255, 255, 255, 255, 255, 255}
;

byte data_dig_cc[] = {
0, 0, 0, 0, 0, 0, 0, 0}
;


byte data = 0;

int latchPin = 10; // set the latch pin
int clockPin = 11; // set the clock pin
int dataPin = 12;// set the data in pin

byte digital_data = 0;

int state = 0;

void setup() {
Serial.begin(31250);
pinMode(2,OUTPUT);
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);

pinMode(latchPin,OUTPUT);
pinMode(clockPin,OUTPUT);
pinMode(dataPin,INPUT);

digitalWrite(latchPin,HIGH);
digitalWrite(clockPin,HIGH);
}

void loop() {
delayMicroseconds(20);
digitalWrite(latchPin,0);

byte myDataIn = 0;
for (int j=7; j>=0; j--)
{
digitalWrite(clockPin, 0);
delayMicroseconds(20);
state = digitalRead(dataPin);
if (state) {
if(data_dig_cc[j] != 1) {
  Serial.print(status_byte);
  Serial.print(dig_cc[j]);
  Serial.print(cc_on_byte);
  data_dig_cc[j] = 1;
}
}
else {
if(data_dig_cc[j] != 0) {
  Serial.print(status_byte);
  Serial.print(dig_cc[j]);
  Serial.print(cc_off_byte);
  data_dig_cc[j] = 0;
}
}
digitalWrite(clockPin, 1);
}
digitalWrite(latchPin, 1);

for(byte i = 0; i <= 7; i++) {  PORTD = i * 4;  data = analogRead(0) >> 3;
if(data_ana_cc[i] != data) {
Serial.print(status_byte);
Serial.print(ana_cc[i]);
Serial.print(data);
data_ana_cc[i] = data;
}
}
}