Posted on May 17, 2011 at 09:46Hello,
I try to use timer to produce interrupt each x µs. To do that, I configure first of all the VIC to enable interrupt from TMR0 with IRQ interrupt, the priority is 0 (most important).
Then I configure the TMR0 with a certain frequency (the value is not important for me), I enable interruption on overflow and I launch it.
When I enable the timer, it is initialized with FFFC so several instrution further there is interruption, the program go in the interrupt function, clear the timer flag, and then wait in main program. After, when the timer overflows, the timer flag is set, but the program don't go to the interrupt function, and I don't understand why.
I verify registers with simulator and there are ok. ISR register bit 4 is set when there is interrupt, VCir has the good value (select TMR0 interrupt and enable), VIC0_VA0R has the good value (adresse of the interrupt function).
The only problem is that the VIC0_VAR register stay at 0. The first time it take the value of VIC0_VA0R, but not the other time. I don't understant why this register stay at 0.
Here my code :
main :
Code:
// SCU Configuration
SCU_APBPeriphClockConfig(__TIM01, ENABLE); // Enable the __TIM01 Clock
SCU_AHBPeriphClockConfig(__VIC,ENABLE); // Enable the __VIC Clock
// VIC Configuration
VIC_DeInit(); // Reset values
VIC_ITCmd(TIM0_ITLine, ENABLE); // Active interrupt from Timer
VIC_Config(TIM0_ITLine, VIC_IRQ, 0); // Configure for generate IRQ
// Timer Configuration
TIM_DeInit(TIM0); // Reset values
TIM_StructInit (&TIM_InitStruct); // Initialize structure
TIM_InitStruct.TIM_Clock_Source = TIM_CLK_APB; // Source clock is internal
TIM_InitStruct.TIM_Prescaler = 0x0F; // Prescaler of 16
TIM_ITConfig(TIM0, TIM_IT_TO, ENABLE); // Active Interrupt on overflow
TIM_Init(TIM0, &TIM_InitStruct); // Initialize Timer 0 TIM_CounterCmd(TIM0, TIM_START); // Enable Timer 0
while(1);
interruption program :
Code:
void TIM0_IRQHandler(void)
{
u32 VAR = VIC0->VAR; // Get VAR value
TIM_ClearFlag(TIM0, TIM_FLAG_TO); // Reset flag
VIC0->VAR = VAR; // Update priority (cf p110 of UM0388)
}
The reading and writing of VAR register is a little strange for me, I don't understand very well why we must do that, but it is noted in the reference manual that we must do that to update the priority hardware). I try with and without do it, and the result is the same.
If somebody can help me, thank you very much.
