Urgent! How to create a 10ms timer?

[eli_k]

Posted on May 18, 2007 at 12:36

Urgent! How to create a 10ms timer?

[eli_k]

Posted on May 16, 2007 at 12:55

Hi,

I am trying to create a 10 ms timer on the STR712 Microcontroller. I would like a timer overflow every 10 ms. exactly. I succeeded doing so, but without accuracy. i reached 10.8ms with the following code: ============================================ TIM_Init(TIM0);// TIM0 configuration TIM_PrescalerConfig(TIM0, 6 ); TIM_ClockSourceConfig(TIM0, TIM_INTERNAL); TIM_ITConfig(TIM0, TIM_TO_IT, ENABLE); TIM_CounterConfig(TIM0, TIM_START); ============================================ Does someone know how to create a timer with accuracy? Does someone have a code for doing so? Thanks for the help! Elra

[kleshov]

Posted on May 16, 2007 at 17:35

You can use the pulse width modulation mode of the timer. Consult the reference manual for details.

Regards, - mike

[neuner]

Posted on May 18, 2007 at 12:36

Hi Elra,

I have a 1ms timer for a STR710 maybe it also works for your 712 (is it the same library for both micros ?) => change Reload value and Prescaler should work to setup your 10ms. void TimerInstall( void ) { /* configure priority of timer IRQ */ EIC_IRQChannelPriorityConfig(T1TIMI_IRQChannel, USR_IRQ_PRIORITY_TIM1); /* enables global IRQ handling of EIC */ EIC_IRQConfig(ENABLE); /* Enable Timer IRQ in interrupt controller */ EIC_IRQChannelConfig(T1TIMI_IRQChannel, ENABLE); /* Initialize the Timer 1 registers to reset values */ TIM_Init ( TIM1 ); /* Configure the Timer 1 Prescaler */ TIM_PrescalerConfig ( TIM1, 0x00 ); /* Enable the Output Compare interrupt for the Timer 1 */ TIM_ITConfig ( TIM1, TIM_OCA_IT, ENABLE ); /* configure and enable Timer 1 */ TIM_OCMPModeConfig ( TIM1, TIM_CHANNEL_A, 0xFFFF, TIM_TIMING, TIM_HIGH ); } -------- void T1TIMI_IRQHandler(void) { /*Clear the TIM1 interrupt flag Bit 14 OCFA */ TIM_FlagClear(TIM1, TIM_OCFA); /* set next time to generate an interrupt */ /* to achieve 1ms at 24Mhz input frequency */ /* the value is set to 24000 ticks */ TIM1->OCAR += 24000; } ------------- Regards Andreas