Hi,
I'm trying to add MIDI to some organ pedals with 74HC595 shift registers and have hit a brick wall. I feel like it might be something simple as I'm relatively new to Arduino and the electronics I have done has been more Audio based.
I have followed the instructions from Code Tinker Hack. Before I go too far hard wiring stuff onto the pedals.
To emulate the button switching on and off, using a jumper lead (with diode) to connect a red wire to a yellow wire (e.g. The 2nd red wire to 3rd yellow wire will activate Switch 18)
Unfortunately though it doesn't work. I rarely get a note on/off value, except for a constant stream of C-1 Note off Values in MIDI-OX. Occasionally when connecting or disconnecting wires I get another value, but rarely.
Some things I have tried:
Adding a 220 Ohm resistor to TX
Several different Arduino Uno's
Several MIDI-USB Interfaces (They all work with other devices)
Two different computers.
Other things I have tried:
Code/instructions from other people such as Evan Kale. (Most of whom seemed to have started with the Code Tinker Hack code.
I am completely stumped. I have been at this on and off for weeks now. I know I could probably do this more simply with a matrix and a Mega as I only have 32 notes, but I also want to add MIDI to some keyboards and stops on the organ, so will need to know how to use the shift registers.
Any help will be hugely appreciated.
// Pin Definitions
// Rows are connected to
const int row1 = 5;
const int row2 = 6;
const int row3 = 7;
const int row4 = 8;
// The 74HC595 uses a serial communication
// link which has three pins
const int clock = 9;
const int latch = 10;
const int data = 11;
uint8_t keyToMidiMap[32];
boolean keyPressed[32];
int noteVelocity = 127;
// use prepared bit vectors instead of shifting bit left everytime
int bits[] = { B00000001, B00000010, B00000100, B00001000, B00010000, B00100000, B01000000, B10000000 };
// 74HC595 shift to next column
void scanColumn(int value) {
digitalWrite(latch, LOW); //Pulls the chips latch low
shiftOut(data, clock, MSBFIRST, value); //Shifts out the 8 bits to the shift register
digitalWrite(latch, HIGH); //Pulls the latch high displaying the data
}
void setup() {
// Map scan matrix buttons/keys to actual Midi note number. Lowest num 41 corresponds to F MIDI note.
keyToMidiMap[0] = 48;
keyToMidiMap[1] = 41;
keyToMidiMap[2] = 42;
keyToMidiMap[3] = 43;
keyToMidiMap[4] = 44;
keyToMidiMap[5] = 45;
keyToMidiMap[6] = 46;
keyToMidiMap[7] = 47;
keyToMidiMap[8] = 56;
keyToMidiMap[1 + 8] = 49;
keyToMidiMap[2 + 8] = 50;
keyToMidiMap[3 + 8] = 51;
keyToMidiMap[4 + 8] = 52;
keyToMidiMap[5 + 8] = 53;
keyToMidiMap[6 + 8] = 54;
keyToMidiMap[7 + 8] = 55;
keyToMidiMap[16] = 64;
keyToMidiMap[1 + 16] = 57;
keyToMidiMap[2 + 16] = 58;
keyToMidiMap[3 + 16] = 59;
keyToMidiMap[4 + 16] = 60;
keyToMidiMap[5 + 16] = 61;
keyToMidiMap[6 + 16] = 62;
keyToMidiMap[7 + 16] = 63;
keyToMidiMap[24] = 72;
keyToMidiMap[1 + 24] = 65;
keyToMidiMap[2 + 24] = 66;
keyToMidiMap[3 + 24] = 67;
keyToMidiMap[4 + 24] = 68;
keyToMidiMap[5 + 24] = 69;
keyToMidiMap[6 + 24] = 70;
keyToMidiMap[7 + 24] = 71;
// setup pins output/input mode
pinMode(data, OUTPUT);
pinMode(clock, OUTPUT);
pinMode(latch, OUTPUT);
pinMode(row1, INPUT);
pinMode(row2, INPUT);
pinMode(row3, INPUT);
pinMode(row4, INPUT);
Serial.begin(31250);
delay(1000);
}
void loop() {
for (int col = 0; col < 8; col++) {
// shift scan matrix to following column
scanColumn(bits[col]);
// check if any keys were pressed - rows will have HIGH output in this case corresponding
int groupValue1 = digitalRead(row1);
int groupValue2 = digitalRead(row2);
int groupValue3 = digitalRead(row3);
int groupValue4 = digitalRead(row4);
// process if any combination of keys pressed
if (groupValue1 != 0 || groupValue2 != 0 || groupValue3 != 0
|| groupValue4 != 0) {
if (groupValue1 != 0 && !keyPressed[col]) {
keyPressed[col] = true;
noteOn(0x91, keyToMidiMap[col], noteVelocity);
}
if (groupValue2 != 0 && !keyPressed[col + 8]) {
keyPressed[col + 8] = true;
noteOn(0x91, keyToMidiMap[col + 8], noteVelocity);
}
if (groupValue3 != 0 && !keyPressed[col + 16]) {
keyPressed[col + 16] = true;
noteOn(0x91, keyToMidiMap[col + 16], noteVelocity);
}
if (groupValue4 != 0 && !keyPressed[col + 24]) {
keyPressed[col + 24] = true;
noteOn(0x91, keyToMidiMap[col + 24], noteVelocity);
}
}
// process if any combination of keys released
if (groupValue1 == 0 && keyPressed[col]) {
keyPressed[col] = false;
noteOn(0x91, keyToMidiMap[col], 0);
}
if (groupValue2 == 0 && keyPressed[col + 8]) {
keyPressed[col + 8] = false;
noteOn(0x91, keyToMidiMap[col + 8], 0);
}
if (groupValue3 == 0 && keyPressed[col + 16]) {
keyPressed[col + 16] = false;
noteOn(0x91, keyToMidiMap[col + 16], 0);
}
if (groupValue4 == 0 && keyPressed[col + 24]) {
keyPressed[col + 24] = false;
noteOn(0x91, keyToMidiMap[col + 24], 0);
}
}
}
void noteOn(int cmd, int pitch, int velocity) {
Serial.write(cmd);
Serial.write(pitch);
Serial.write(velocity);
}
