Example
// This is a more complex MIDI THRU. This version uses a queue. Queues are important because some
// MIDI messages can be interrupted for real time events. If you are generating your own messages,
// you may need to stop your message to let a "real time" message through and then resume your message.
#define QUEUE_DEPTH 128
// Queue Logic for storing messages
int headQ = 0;
int tailQ = 0;
unsigned char tx_queue[QUEUE_DEPTH];
void setup() {
// put your setup code here, to run once:
// Set MIDI baud rate:
Serial.begin(31250);
}
// getQDepth checks for roll over. Folks have told me this
// is not required. Feel free to experiment.
int getQDepth() {
int depth = 0;
if (headQ < tailQ) {
depth = QUEUE_DEPTH - (tailQ - headQ);
} else {
depth = headQ - tailQ;
}
return depth;
}
void addQueue (unsigned char myByte) {
int depth = 0;
depth = getQDepth();
if (depth < (QUEUE_DEPTH-2)) {
tx_queue[headQ] = myByte;
headQ++;
headQ = headQ % QUEUE_DEPTH; // Always keep the headQ limited between 0 and 127
}
}
unsigned char deQueue() {
unsigned char myByte;
myByte = tx_queue[tailQ];
tailQ++;
tailQ = tailQ % QUEUE_DEPTH; // Keep this tailQ contained within a limit
// Now that we dequeed the byte, it must be sent.
return myByte;
}
void loop() {
if (getQDepth>0) {
Serial.write(deQueue());
}
}
// The little function that gets called each time loop is called.
// This is automated somwhere in the Arduino code.
void serialEvent() {
if (Serial.available()) {
// get the new byte:
addQueue((unsigned char)Serial.read());;
}
}
