timer1 always reads 8 bit value?

Projects Programming
1

Hello All

Not sure what i am doing wrong but when i read timer1 using the atomic safe code in the spec sheet for the atmega i never get a value above 8 bits?

I read this constantly in my loop and store the max value after 100000 loops (also into an unsigned int). It is never more than 255.

I have no prescaler (therefore read that ckdiv8 is not set), the arduino is an atmega328p revision 3 with 16mhz crystal.

Atomic read as below.

unsigned int TIM16_ReadTCNT1()
{
unsigned char sreg;
unsigned int i;
/* Save global interrupt flag /
sreg = SREG;
/ Disable interrupts /
cli();
/ Read TCNT1 into i /
i = TCNT1;
/ Restore global interrupt flag */
SREG = sreg;
return i;
}

Any ideas?

Cheers

J

2

Look at the init() function that runs before any of your code. It puts Timer1 into 8 bit mode so the PWM on those pins will work the same as the others.

If you want 16bit mode, you'll have to set the timer up yourself.

3

Thanks for the reply Delta_G

Not sure where the init function is that you mention, it's not in the code i wrote that is for sure. Could you provide a filename for where this init function resides?

Thanks

J

4

It is in wiring.c if I remember right.

Behind the scenes the IDE hides the main function. It is worth taking a look at. I believe it is in Main.cpp. Search the folder where you installed the IDE.