Does anyone have a libopencm3 based example, against the STM32 F2,
that illustrates ISR's invoking based on timers?
I did try using a couple of the examples (see timer.c) in the F1
directory to no avail; I've got a few attempts at it, and it looks like
(guessing, didn't hook up a debugger yet) the ISR is just not being
called.
This is just the bare STM32F205RE sitting in a breadboard, with a
crystal and some caps. (No dev/eval board.)
// set to 120MHz - success
rcc_clock_setup_hse_3v3 ( &hse_8mhz_3v3 [ CLOCK_3V3_120MHZ ] );
The good bits .. mostly ripped from examples :)
static void nvic_setup(void) {
nvic_enable_irq(NVIC_TIM2_IRQ);
nvic_set_priority(NVIC_TIM2_IRQ, 1);
}
static void timer2_setup ( void ) {
/* Enable TIM2 clock. */
rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_TIM2EN);
/* Set timer start value. */
TIM_CNT(TIM2) = 1;
/* Set timer prescaler. 72MHz/1440 => 50000 counts per second. */
TIM_PSC(TIM2) = 2000; // 120M/2000 = 60k/second
/* End timer value. If this is reached an interrupt is generated. */
TIM_ARR(TIM2) = 60000;
/* Update interrupt enable. */
TIM_DIER(TIM2) |= TIM_DIER_UIE;
/* Start timer. */
TIM_CR1(TIM2) |= TIM_CR1_CEN;
#endif
return;
}
void tim2_isr ( void ) {
GPIO_ODR(GPIOC) ^= GPIO3; // GPIO stuff works fine, outside of the ISR
TIM2_SR &= ~TIM_SR_UIF; //clearing update interrupt flag
//TIM_SR(TIM2) &= ~TIM_SR_UIF; /* Clear interrrupt flag. */
}
.. and the relevent bits of main:
#if 1
//__enable_irq();
cm_enable_interrupts();
gpio_setup();
gpio_set ( GPIOC, GPIO3 );
nvic_setup();
timer2_setup();
while ( 1 ) {
__asm__("nop");
} // while forever
#endif
Now, on the other hand, the code below works -- not using an ISR,
just polling things:
polling timer setup:
#if 0 // simple manual setup
rcc_peripheral_enable_clock ( &RCC_APB1ENR, RCC_APB1ENR_TIM2EN );
// 120,000,000 / 1000 == 120,000
TIM2_CR1 |= TIM_CR1_CEN;
TIM2_PSC = 1000; //setting prescaler to 1000
TIM2_ARR = 60000; //auto reload value adjusted for 1 second
#endif
polling timer check:
#if 0
gpio_setup();
gpio_set ( GPIOC, GPIO3 );
timer2_setup();
while ( 1 ) {
while (!(TIM2_SR & (TIM_SR_UIF))) ; //polling for update interrupt
flag
TIM2_SR &= ~TIM_SR_UIF; //clearing update interrupt flag
GPIO_ODR(GPIOC) ^= GPIO3;
} // while forever
#endif
So much of the code is working fine, but I'm obviously missing
something to enable the ISR itself :)
Any tips?
jeff
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