AVR-Chat

On Sep 28, 2011, at 6:47 AM, Jim Wagner wrote:

> What is your system clock?
>
> Jim Wagner
>
> On Sep 27, 2011, at 10:41 PM, Philippe Habib wrote:
>
>> As it turned out, I need timer 0 to run PWM on a pin so I have to
>> use timer 1 for my timer tick.
>>
>> Using what I learned from timer 0, I was hoping it would be easy to
>> generate a 10ms tick using timer 1.
>>
>> Here is my setup:
>>
>> TCCR1A = (0 << WGM10) | (0 << WGM11); // Make sure these are low for
>> CTC
>> TCCR1B |= (0 << WGM12); // CTC mode
>> TCCR1B |= (1 << CS12); // Use system clock

Don't know why you have this here.

>> TCCR1B |= (1 << CS10) | (0 << CS11) | (0 << CS12); // no div, full
>> clock

Combined with the above line you have a clock select value of 5 or  
divide by 1024, not 1


>> TIMSK1 = (1 << OCIE1A);	 // Set int for match on A
>>
>> OCR1A = 64000; // compare value
>> //	OCR1AH = 0xFF; // MSB
>> //	OCR1AL = 0x00;	// LSB

64000 decimal is 0xFA00

This gives you a interrupt rate of .122 Hz or about every 8 seconds.   
(assuming 8MHz clock which I believe is the case).

To get 100mS you would need:

TCCR1B |= (0 << CS10) | (1 << CS11) | (0 << CS12); 		// divide by 8
OCR1A	= 10000;

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