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/*
Here is an example of how to use avr-midi
this was written for an atmega16 using a 12Mhz clock in an stk500
the switch inputs of the STK500 are connected to PORTC
switch 0 and 1 increment and decrement [respectively] a midi program and
send the appropriate midi program change
switch 2 sends a note on message when the button is pushed and a note off
when the button is released
the rest of the switches send CC messages, a 1 when the button is down and a
0 when the button is released
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <inttypes.h>
#include "serial_midi.h"
#define MIDI_CLOCK_12MHZ_OSC 23
#define MIDI_CLOCK_RATE MIDI_CLOCK_12MHZ_OSC
//how many times to we read the buttons before we say they're valid
#define INPUT_HISTORY 4
//this is the midi channel we'll be sending on.. 0 is midi channel 1
#define MIDI_CHAN 0
int main(void) {
//index for looping
uint8_t i, j;
bool consistent;
//is the button up
bool up;
//midi program
uint8_t program = 0;
//button inputs, for debouncing
uint8_t inputs[INPUT_HISTORY];
uint8_t curInput = 0;
uint8_t lastInput = 0;
uint8_t historyIndex = 0;
//PORTC is in input with internal pullups
DDRC = 0x00;
PORTC = 0xFF;
//init the button history
for(i = 0; i < INPUT_HISTORY; i++)
inputs[i] = 0;
//init midi, give the clock rate setting, indicate that we want only output
MidiDevice * midi_device = serial_midi_init(MIDI_CLOCK_RATE, true, false);
while(1){
//grab the inputs
inputs[historyIndex] = PINC;
curInput = lastInput;
//debounce inputs
//for each input
for(i = 0; i < 8; i++){
consistent = true;
//the STK500 has 1 for up and 0 for down if you're using the on board buttons
up = (bool)(0x1 & (inputs[0] >> i));
//check the history to make sure we have the same value for this input
//for the whole history
for(j = 1; j < INPUT_HISTORY; j++){
if(up != (bool)(0x1 & (inputs[j] >> i))){
consistent = false;
break;
}
}
//if we have the same value for the whole history then store it in
//curInput
if(consistent){
if(up) {
//store the current input state
curInput |= (1 << i);
//if the last input was a 0 and the current is a 1
if(((lastInput >> i) & 0x1) == 0){
//we don't do anything on up for the first two buttons
//send the appropriate midi data
if(i == 2){
midi_send_noteoff(midi_device, MIDI_CHAN, 64, 30);
} else if(i > 1)
midi_send_cc(midi_device, MIDI_CHAN, i - 3, 0);
}
} else {
//store the current input state
curInput &= ~(1 << i);
//if the last input was a 1 and the current is a 0
if(((lastInput >> i) & 0x1) == 1){
//send the appropriate midi data
switch(i){
case 0:
program = (program + 1) % 128;
midi_send_programchange(midi_device, MIDI_CHAN, program);
break;
case 1:
program = (program - 1) % 128;
midi_send_programchange(midi_device, MIDI_CHAN, program);
break;
case 2:
midi_send_noteon(midi_device, MIDI_CHAN, 64, 127);
break;
default:
midi_send_cc(midi_device, MIDI_CHAN, i - 3, 1);
break;
}
}
}
}
}
//update the history index
historyIndex = (historyIndex + 1) % INPUT_HISTORY;
//store the curInput as lastInput for the next loop
lastInput = curInput;
}
return 0;
}
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