50 lines
1.1 KiB
Arduino
50 lines
1.1 KiB
Arduino
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#include <Wire.h>
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//helper to check if a bit is set
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#define BIT_IS_SET(i, bits) (1 << i & bits)
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//array for inputs on bank a of MCP23017
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boolean button[8];
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void setup() {
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//set MIDI bautdrate
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Serial.begin(31250);
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//start I2C
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Wire.begin();
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}
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void loop() {
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//0x20 hardware address of MCP23017 (A0,A1,A2 to ground)
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Wire.beginTransmission(0x20);
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Wire.write(0x12); // set MCP23017 memory pointer to GPIOA address
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Wire.endTransmission();
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Wire.requestFrom(0x20, 1); // request one byte of data from MCP20317
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int inputs = Wire.read();
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delayMicroseconds(10);
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int i;
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for(i=0;i<8;i++) {
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//check if button is pressed
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if (BIT_IS_SET(i,inputs)) {
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//only send Note-on, when button was not pressed before
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if(!button[i]) {
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button[i] = true;
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midiSignal(144,60+i,115);
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}
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} else {
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//only send Note-off, when button was pressed before
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if(button[i]) {
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button[i] = false;
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midiSignal(128,60+i,0);
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}
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}
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}
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}
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//send MIDI signal through softwareserial
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void midiSignal(byte b1, byte b2, byte b3) {
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Serial.write(b1);
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Serial.write(b2);
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Serial.write(b2);
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}
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