Need code sample for timer interrupts.

jonny_bee_henry · ‎2006-10-18

Posted on October 19, 2006 at 07:37

jonny_bee_henry · ‎2011-05-17

Posted on May 17, 2011 at 09:33

I cannot figure out how to get a timer to generate an interrupt at a fixed interval. This question has been asked here at least twice recently, and both times was answered with an incomplete code fragment that I cannot compile (using the IAR dev kit). For example, I just want to configure TIM0 to interrupt every 10ms, and have its interrupt service routine increment a global counter that I can print out periodically in the main loop. Can someone please provide the code to do that?

egads · ‎2011-05-17

Posted on May 17, 2011 at 09:33

Keil's STR9 ''Blinky'' example has a timer based interrupt example.

I think you can down load this from the keil website. I know thi sis not an IAR example, but maybe it will lead you down the correct path!

jonny_bee_henry · ‎2011-05-17

Posted on May 17, 2011 at 09:33

Thanks for the pointer, but I'm looking for sample code using the STR91x library functions so that I can understand how they work (i.e what I'm doing wrong). The Keil example doesn't use the library.

jonny_bee_henry · ‎2011-05-17

Posted on May 17, 2011 at 09:33

Maybe if I just give my code, somebody can find the problem:

main.c

------

#include ''91x_lib.h''

#include

int IRQ_counter = 0;

main() {

TIM_InitTypeDef TIM0_InitStructure;

// usual clock & uart initialization, etc. omitted

/* TIM0 Initialization */

#define TIM0Prescaler 0xFF

#define PWMFreqInHz 100

#define PWMPulsePercent 33

SCU_APBPeriphClockConfig(__TIM01, ENABLE);

TIM_DeInit(TIM0);

TIM_StructInit(&TIM0_InitStructure);

/* TIM0 Configuration in PWM Mode */

TIM0_InitStructure.TIM_Mode = TIM_PWM;

TIM0_InitStructure.TIM_Clock_Source = TIM_CLK_APB;

TIM0_InitStructure.TIM_Prescaler = TIM0Prescaler;

TIM0_InitStructure.TIM_Pulse_Level_1 = TIM_HIGH;

TIM0_InitStructure.TIM_Period_Level = TIM_LOW;

TIM0_InitStructure.TIM_Full_Period = (SCU_GetMCLKFreqValue())*1000 / ((TIM0Prescaler + 1) * PWMFreqInHz);

TIM0_InitStructure.TIM_Pulse_Length_1 = TIM0_InitStructure.TIM_Full_Period * PWMPulsePercent / 100;

TIM_Init (TIM0, &TIM0_InitStructure);

/* Enable and configure the priority of the IRQ Channel*/

SCU_AHBPeriphClockConfig(__VIC, ENABLE);

VIC_DeInit();

VIC_Config(TIM0_ITLine, VIC_IRQ, 0);

VIC_ITCmd(TIM0_ITLine, ENABLE);

TIM_ITConfig(TIM0, TIM_IT_TO, ENABLE);

TIM_CounterCmd(TIM0, TIM_START);

while (1) {

if (IRQ_counter % 100 == 0)

putchar('.');

}

91x_it.c

---------

void TIM0_IRQHandler(void)

{

extern int IRQ_counter;

IRQ_counter++;

TIM_ClearFlag(TIM0, TIM_FLAG_TO);

}

stefano239955_stm1_stmicro · ‎2011-05-17

Posted on May 17, 2011 at 09:33

hi jonny_h

I use a similar configuration but with a

different irq event:

/* Enable the Timer Overflow interrupt */

TIM_ITConfig(TIM0, TIM_IT_OC2, ENABLE);

I'm not sure but for what I understand the

pwm mode doesn't trig the Timer overflow (TO).

If you like to use the TO event I suggest to you to

use a different configuration for the timer, like

output compare mode

egads · ‎2011-05-17

Posted on May 17, 2011 at 09:33

Quote:

On 18-10-2006 at 00:34, Anonymous wrote:

The Keil example doesn't use the library.

To me that's a positive. I find the ST lib stuff to be overly complicated and written in a way that is hard to figure out what its doing. I'm much more comfortable configuring my peripherals with simple writes to registers.

yuantuh · ‎2011-05-17

Posted on May 17, 2011 at 09:33

hi jonny_h,

Are you all right? Try the following piece of code please. It works in my board.

#include ''91x_lib.h''

#define TIM0Prescaler 0xFF

#define PWMFreqInHz 100

#define PWMPulsePercent 33

TIM_InitTypeDef TIM_InitStructure;

void TIM0_IRQHandlerInvoked(void)

{

// balah balah

// ...

/*Clear the TIM_TO flag for the next interrupt*/

TIM_ClearFlag(TIM0, TIM_FLAG_TO);

}

void main(void)

{

#ifdef DEBUG

debug();

#endif

/*-------------------- System Clock Config --------------------*/

SCU_MCLKSourceConfig(SCU_MCLK_OSC);

// Someone said PLL = 96 MHz is unstable, so change PLL = 48 MHz

//SCU_PLLFactorsConfig(0xC0, 0x19, 0x2); // PLL = 96 MHz

SCU_PLLFactorsConfig(0xC0, 0x19, 0x3); // PLL = 48 MHz

SCU_PLLCmd(ENABLE);

SCU_MCLKSourceConfig(SCU_MCLK_PLL);

/* Enable VIC clock */

SCU_AHBPeriphClockConfig(__VIC,ENABLE);

VIC_DeInit();

/* Enable TIM0 clock */

SCU_APBPeriphClockConfig(__TIM01, ENABLE);

TIM_DeInit(TIM0);

TIM_StructInit(&TIM_InitStructure);

TIM_InitStructure.TIM_Mode = TIM_PWM;

TIM_InitStructure.TIM_Clock_Source = TIM_CLK_APB;

TIM_InitStructure.TIM_Prescaler = 0xFF;

TIM_InitStructure.TIM_Pulse_Level_1 = TIM_HIGH;

TIM_InitStructure.TIM_Period_Level = TIM_LOW;

TIM_InitStructure.TIM_Full_Period = (SCU_GetMCLKFreqValue())*1000 / ((TIM0Prescaler + 1) * PWMFreqInHz);

TIM_InitStructure.TIM_Pulse_Length_1 = TIM_InitStructure.TIM_Full_Period * PWMPulsePercent / 100;

/* Initialize the Timer 0 */

TIM_Init (TIM0, &TIM_InitStructure);

/* Enable the Timer Overflow interrupt */

TIM_ITConfig(TIM0, TIM_IT_TO, ENABLE);

VIC_Config(TIM0_ITLine, VIC_IRQ, 4);

VIC_ITCmd(TIM0_ITLine, ENABLE);

/* Start the Timer counter */

TIM_CounterCmd(TIM0, TIM_START);

while(1)

{

// balah balah

// ...

}

in 91x_it.c

---------

extern void TIM0_IRQHandlerInvoked(void);

void TIM0_IRQHandler(void)

{

TIM0_IRQHandlerInvoked();

}

91x_it.h

#ifndef __91x_CONF_H

#define __91x_CONF_H

#define DEBUG

#define _VIC

#define _VIC0

#define _TIM

#define _TIM0

#define _SCU

#ifndef _Main_Crystal

#define _Main_Crystal 25000

#endif

craig239955_st · ‎2011-05-17

Posted on May 17, 2011 at 09:33

I use following code on my KEIL STR9 evaluation board.

Timer 1 is used as a 1mS interrupt generator, 2 others are used a counters.

Luc Vercruysse.

Robosoft n.v.

__irq void TIM1_IRQHandler (void)

{

test = test + 1;

TIM_ClearFlag(TIM1,TIM_FLAG_OC1); //Clear pending interrupt flag

VIC0->VAR = 0x0000; //End of interrupt

VIC1->VAR = 0x0000;

TIM1->OC1R += 200; //every 1mS

}

extern __irq void TIM1_IRQHandler(void);

extern long test;

TIM_InitTypeDef Timer ;

GPIO_InitTypeDef GPIO;

int main (void) {

//Interrupt setup

SCU_APBPeriphClockConfig(__VIC,ENABLE);

VIC_DeInit();

VIC_Config(TIM1_ITLine,VIC_IRQ,1);

VIC_ITCmd(TIM1_ITLine,ENABLE);

//Timer Setup

SCU_APBPeriphClockConfig(__TIM01, ENABLE); /* Enable the clock for TIM0 and TIM1 */

SCU_APBPeriphClockConfig(__TIM23, ENABLE); /* Enable the clock for TIM0 and TIM1 */

TIM_DeInit(TIM0); /* TIM0 Deinitialization */

TIM_DeInit(TIM1); /* TIM1 Deinitialization */

TIM_DeInit(TIM2); /* TIM2 Deinitialization */

SCU_TIMCLKSourceConfig(SCU_TIM01,SCU_TIMCLK_EXT);

SCU_TIMCLKSourceConfig(SCU_TIM23,SCU_TIMCLK_EXT);

//Init Counter 0 (as a counter)

Timer.TIM_Mode = TIM_OCM_CHANNEL_1;

Timer.TIM_Clock_Source = TIM_CLK_EXTERNAL;

Timer.TIM_Clock_Edge = TIM_CLK_EDGE_RISING;

TIM_Init (TIM0, &Timer);

TIM_CounterCmd(TIM0,TIM_CLEAR);

TIM_CounterCmd(TIM0,TIM_START);

//Init Counter 2 (as a counter)

Timer.TIM_Mode = TIM_OCM_CHANNEL_1;

Timer.TIM_Clock_Source = TIM_CLK_EXTERNAL;

Timer.TIM_Clock_Edge = TIM_CLK_EDGE_RISING;

TIM_Init (TIM2, &Timer);

TIM_CounterCmd(TIM2,TIM_CLEAR);

TIM_CounterCmd(TIM2,TIM_START);

//Init Timer 1 (1 mSinterrupt (FCLK = 96MHz)

Timer.TIM_Mode = TIM_OCM_CHANNEL_1;

Timer.TIM_Clock_Source = TIM_CLK_APB;

Timer.TIM_Clock_Edge = TIM_CLK_EDGE_RISING;

TIM_Init (TIM1, &Timer);

TIM_PrescalerConfig(TIM1,240);

TIM_CounterCmd(TIM1,TIM_START);

TIM_ITConfig(TIM1,TIM_IT_OC1,ENABLE); //output capture

.....

}