Quick test on the L476-DISCO, works for me with LPTIM1_CMP=0x7FFF - green LED blinked in the ISR blinks.
(gdb) p /x *LPTIM1
$57 = {ISR = 0x3, ICR = 0x0, IER = 0x1, CFGR = 0x0, CR = 0x1, CMP = 0x7fff,
ARR = 0xffff, CNT = 0x9357, OR = 0x0}
(gdb)
(higher LPTIM1->ISR bits are cleared, as I was lazy and in the ISR simply cleared all bits)
Will be some other problem at your place. Perhaps tell us why do you think the interrupt is not working.
JW
// trying LPTIM compare interrupt
// https://community.st.com/s/question/0D50X00009bNKtNSAW/hi-im-using-a-stm32l476-and-have-lptim1-in-free-running-mode-with-compare-match-enabled-i-never-get-interrupts-with-compare-match-value-0x7fff-values-higherlower-are-ok-any-ideascheershw
#define DISCOL4 // LEDs are: PB2 (red), PE8 (green)
#define LPTIM_PWM_RED // PB2 at AF1 is LPTIM1_OUT
#include <stdint.h>
#include "stm32l476xx.h"
// -------- stuff missing from the stm32XXXxx.h
// GPIOx_MODER - 2 bits per pin
#define GPIO_Mode_In 0x00 // GPIO Input Mode
#define GPIO_Mode_Out 0x01 // GPIO Output Mode
#define GPIO_Mode_AlternateFunction 0x02 // GPIO Alternate function Mode
#define GPIO_Mode_Analog 0x03 // GPIO Analog Mode
#define AFRL AFR[0]
#define AFRH AFR[1]
#define GPIO_AFRL_AFRL0_0 ((uint32_t)0x00000001)
#define GPIO_AFRL_AFRL1_0 ((uint32_t)0x00000010)
#define GPIO_AFRL_AFRL2_0 ((uint32_t)0x00000100)
#define GPIO_AFRL_AFRL3_0 ((uint32_t)0x00001000)
#define GPIO_AFRL_AFRL4_0 ((uint32_t)0x00010000)
#define GPIO_AFRL_AFRL5_0 ((uint32_t)0x00100000)
#define GPIO_AFRL_AFRL6_0 ((uint32_t)0x01000000)
#define GPIO_AFRL_AFRL7_0 ((uint32_t)0x10000000)
#define GPIO_AFRH_AFRH8_0 ((uint32_t)0x00000001)
#define GPIO_AFRH_AFRH9_0 ((uint32_t)0x00000010)
#define GPIO_AFRH_AFRH10_0 ((uint32_t)0x00000100)
#define GPIO_AFRH_AFRH11_0 ((uint32_t)0x00001000)
#define GPIO_AFRH_AFRH12_0 ((uint32_t)0x00010000)
#define GPIO_AFRH_AFRH13_0 ((uint32_t)0x00100000)
#define GPIO_AFRH_AFRH14_0 ((uint32_t)0x01000000)
#define GPIO_AFRH_AFRH15_0 ((uint32_t)0x10000000)
#define GPIO_AlternateFunction_SYS 0 /* default */
#define GPIO_AlternateFunction_TIM1_1 1
#define GPIO_AlternateFunction_TIM2_1 1
#define GPIO_AlternateFunction_TIM5_1 1
#define GPIO_AlternateFunction_TIM8_1 1
#define GPIO_AlternateFunction_LPTIM1 1
#define GPIO_AlternateFunction_TIM1_2 2
#define GPIO_AlternateFunction_TIM2_2 2
#define GPIO_AlternateFunction_TIM3 2
#define GPIO_AlternateFunction_TIM4 2
#define GPIO_AlternateFunction_TIM5_2 2
#define GPIO_AlternateFunction_TIM8_3 3
// [etc]
#define GPIO_AlternateFunction_EVENTOUT 15
// -------- trivial loopdelay
void LoopDelay(volatile uint32_t n) {
while(n > 0) n--;
}
#define DELAY_CONSTANT 50000
// -------- main
int main(void) {
RCC->AHB2ENR |= 0
| RCC_AHB2ENR_GPIOBEN
| RCC_AHB2ENR_GPIOEEN
;
GPIOB->MODER = (GPIOB->MODER
& (~GPIO_MODER_MODER2) // RED LED
) | (0
| (GPIO_Mode_AlternateFunction * GPIO_MODER_MODER2_0) // RED LED
);
GPIOE->MODER = (GPIOE->MODER
& (~GPIO_MODER_MODER8) // GREEN LED
) | (0
| (GPIO_Mode_Out * GPIO_MODER_MODER8_0) // GREEN LED
);
GPIOB->AFRL = (GPIOB->AFRL
& (~GPIO_AFRL_AFRL2) // RED LED
) | (0
| (GPIO_AlternateFunction_LPTIM1 * GPIO_AFRL_AFRL2_0) // RED LED
);
RCC->APB1ENR1 |= 0
| RCC_APB1ENR1_LPTIM1EN
;
LPTIM1->CR = 0
| LPTIM_CR_ENABLE
;
/*
LPTIM1->CFGR = 0
| LPTIM_CFGR_WAVPOL // Waveform shape polarity
;
*/
LPTIM1->ARR = 0xFFFF; // must be changed only when _CR.ENABLE = 1
LPTIM1->CMP = 0x7FFF;
LPTIM1->IER = 0
| LPTIM_IER_CMPMIE // enable interrupt upon compare match
;
LPTIM1->CR = 0
| LPTIM_CR_ENABLE
| LPTIM_CR_CNTSTRT // must be started only when _CR.ENABLE = 1
;
NVIC_EnableIRQ(LPTIM1_IRQn);
while(1) {
/*
GPIOE->BSRR = 0
| GPIO_BSRR_BS_8 // GREEN LED - set
;
LoopDelay(DELAY_CONSTANT);
GPIOE->BSRR = 0
| GPIO_BSRR_BR_8 // GREEN LED - reset
;
LoopDelay(DELAY_CONSTANT);
*/
}
}
// ISR
void LPTIM1_IRQHandler(void) __attribute__((interrupt));
void LPTIM1_IRQHandler(void) {
static uint32_t blinkenCount;
#define BLINKEN_NR 10
LPTIM1->ICR = 0xFF; // as we have enabled only one, we don't care here, just summarily clear all interrupt sources
blinkenCount++;
if (blinkenCount == BLINKEN_NR) {
GPIOE->BSRR = 0
| GPIO_BSRR_BS_8 // GREEN LED - set
;
} else if (blinkenCount >= 2 * BLINKEN_NR) {
GPIOE->BSRR = 0
| GPIO_BSRR_BR_8 // GREEN LED - reset
;
blinkenCount = 0;
}
}
