A simple PWM beep using timers 1 and 2

Using Arduino Programming Questions
1

I am writing a simple beep function.
Yes, I know I can do this using the Arduino tone() function, but I'm trying to implement
this beep function using low-level timer control.

In the following code, timer 2 generates a periodic interrupt which calculates the amplitude of the beep sine wave and timer 1 generates the beep PWM waveform.

As written, it does not work, so I am asking for help. What am I missing?

typedef void (*func_t)(void);
volatile func_t func_ptr;

void beep(uint8_t sw) {
if (sw == ON) {
// turn on
func_ptr = beep_isr;
OCR2A = T2OCRX;
TCCR1A |= (1 << COM1A1);
TIMSK2 |= (1 << OCIE2A);
} else {
// turn off
TCCR1A &= ~(1 << COM1A1);
TIMSK2 &= ~(1 << OCIE2A);
}
}

// beep interrupt handler
void beep_isr() {
minsky(); // calculate sine value msin
OCR1AL = (msin >> ((16-cwvol) >> 1)) + 128;
}

// timer2 interrupt handler
ISR(TIMER2_COMPA_vect) {
func_ptr();
}

2

Code tags.
The rest of your code.

3

Welcome to the forums. Please read this and then edit your post to include code tags and the entire sketch.

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4

My question is about timer operation. I hope enough code there to understand how I am trying to control the timers.

5

You are missing setup() and loop().
You are missing declarations for 'ON', 'T2OCRX', 'msin', 'cwvol', and the minsky() function.

6

Looks OK to me, assuming all of the missing code is perfect and your wiring is correct.

7

Thanks John, I got it working. And you are right, the code I posted worked fine. The problem I was having was in a different area. Process of elimination. Marking this issue as closed.

8

Still missing the code tags.

9

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