midi clock and 16th notes test program

midi-computer-test.c

unsigned long BPM = 120;
unsigned long PPQ = 24;
unsigned long PPQ_T;
unsigned long SECONDS_IN_MINUTE = 60;
unsigned long MICROSECONDS_PER_PPQ = (SECONDS_IN_MINUTE * 1000000) / (BPM * PPQ);

unsigned long _micros;

unsigned long MICROSECONDS_PER_STEP = (SECONDS_IN_MINUTE * 1000000) / (BPM * 4);
unsigned long STEP_T;
bool isNoteOn;

void setup() {

  Serial.begin(56000);

  PPQ_T = micros();
  STEP_T = micros();
  _micros = micros();
  isNoteOn = false;
  
}

void loop() {

  _micros = micros();
  if(_micros - PPQ_T >= MICROSECONDS_PER_PPQ) {
    PPQ_T = _micros;
    Serial.write((int)248);
  }
  if(_micros - STEP_T >= MICROSECONDS_PER_STEP) {
    STEP_T = _micros;
    if(isNoteOn == true) {
      Serial.write((uint8_t)128); // note OFF
      Serial.write((uint8_t)60);  // note value
      Serial.write((uint8_t)64);  // note velocity      
      isNoteOn = false;
    }
    Serial.write((uint8_t)144); // note ON
    Serial.write((uint8_t)60);  // note value
    Serial.write((uint8_t)64);  // note velocity
    isNoteOn = true;
  }

}