xtal(oscillator problem) - a way to generate 1 sec delay

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siddhukb

Joined: 07 Aug 2008
Posts: 3

29 May 2009 3:47 xtal oscilator problem

I am using using a 12mz crystal and atmega 16 and mikroc pro for avr complier.
when i give a delay of 1 sec the led blinking doesnt blink at 1 sec,it takes too long to blink.

Code:

delay_ms(1000);

do i need to configure anything?
or is there any other way to generate 1 sec delay.?

thanking you,
siddharth

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sau_sol

Joined: 27 Feb 2008
Posts: 249
Helped: 27
Location: India

29 May 2009 5:19 Re: xtal(oscillator problem)

use a timer with say 10ms of overflow then increment a variable in interrupt for 100 so you will get
10ms *100 = 1000ms = 1s delay

so calculate according the data sheet the value to be fed in the timer

jumper2high

Joined: 24 May 2009
Posts: 62
Helped: 3
Location: Serbia

29 May 2009 10:54 Re: xtal(oscillator problem)

siddhkub, you should check the settings in MikroC, specifically make sure you've selected the right frequency in there. The "real time" delays depend on CPU clock, since at 4Mhz you need 1.000.000 clock cycles to generate a 1 second delay, but at 48Mhz you need 12.000.000 clock cycles for the same delay.

If MikroC thinks you're running at 48Mhz, but you're actually running at 4 Mhz, the compiled code will have delays 12 times longer than what you wanted.