asynchronous - Arduino - Tone without delay -
i'm trying play tone while changing on lcd display. i've searched around , tried protothreads, seems delay still blocks program. i've tried removing delay altogether, skipped except last note. there way play tone without using delay? (millis perhaps?)
sample tone sequence:
//beats per minute #define bpm 250 //constants, try not touch, touch anyways. #define q 60000/bpm //quarter note #define w 4*q //whole note #define h 2*q //half note #define e q/2 //eigth note #define s q/4 //sixteenth note void tonefunction() { tone(tonepin,c5,q); delay(1+w); tone(tonepin,c5,q); delay(1+w); tone(tonepin,c5,q); delay(1+w); tone(tonepin,c6,w); }
you can set timer , put note changing logic interrupt service routine (isr).
each x milliseconds, timer reset , interrupt main loop. isr run , pick next note , call tone function. after exiting isr, program continues point interrupted.
i have attached code used in 1 of projects. timer interrupt main loop every 50ms (20 hz), therfore have put own numbers in ocr1a , pre-scaler. please read more timer interrupt in arduino understand how (for example here: http://www.instructables.com/id/arduino-timer-interrupts/step2/structuring-timer-interrupts/). can see example @ end of page (http://playground.arduino.cc/code/timer1) more user friendly way of doing this.
setup() { .... /* set timer1 interrupt 20hz */ cli();//stop interrupts tccr1a = 0;// set entire tccr1a register 0 tccr1b = 0;// same tccr1b tcnt1 = 0;//initialize counter value 0 ocr1a = 781; // approximately 20hz tccr1b |= (1 << wgm12);// turn on ctc mode tccr1b |= (1 << cs12) | (1 << cs10); // 1024 presxaler timsk1 |= (1 << ocie1a); // enable timer compare interrupt sei();//allow interrupts } ... isr(timer1_compa_vect){ // pick next note } 
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