LPTIM_COUNTER_START Problem

as a matter of fac, I comment "if (LPTIM_WaitForFlag(hlptim, LPTIM_FLAG_ARROK) == HAL_TIMEOUT)", not put return OK as I said, so the waitforflag is ignored.

Use a debugger to inspect timer registers. Check register values with reference manual to ​verify correct bits are set

On STM32L4R I use LPTIM to drive buzzer audio notes or short delays in used. Code extract: (48MHz SYSCLK)

Maybe you'll find some clues from this?

extern LPTIM_HandleTypeDef hlptim1;
 
void LPTIM1_Init(void) {
 LPTIM_HandleTypeDef* hlptim = &hlptim1;
 // Set the LPTIM2 clock to PCLK because HSI16 is off
// RCC->CCIPR &= ~(3<<20);
// RCC->CCIPR |= (0<<20); 48 MHz = MSI = APB
 HAL_NVIC_SetPriority(LPTIM1_IRQn, 2/*0*/, 0);
 HAL_NVIC_EnableIRQ(LPTIM1_IRQn);
 hlptim->Instance->CFGR |= LPTIM_PRESCALER_DIV16; // 3 ticks = 1 us
 /* Set WAVE bit to enable the set once mode */
 hlptim->Instance->CFGR |= LPTIM_CFGR_PRELOAD;// LPTIM_CFGR_WAVE;
 
 /* Enable Autoreload match interrupt */
 hlptim->Instance->ICR |= 0x0002; // ARRMCF clear flag 
 __HAL_LPTIM_ENABLE_IT(hlptim, LPTIM_IT_ARRM);
 
 /* Enable Compare match interrupt */
// __HAL_LPTIM_ENABLE_IT(hlptim, LPTIM_IT_CMPM);
 
 /* Enable the Peripheral */
// __HAL_LPTIM_ENABLE(hlptim);
}
 
void LPTIM1_SetTick_us(uint32_t delay_us) {
 LPTIM_HandleTypeDef* hlptim = &hlptim1;
 
 if((delay_us/3)>0xFFFF) TrapError(); // change the clock prescaler if looking at more than one milisecond
 if(delay_us==0) {
 // turn the timer event off
 __HAL_LPTIM_DISABLE_IT(hlptim, LPTIM_IT_ARRM);
 __HAL_LPTIM_DISABLE(hlptim);
 return; // done
 }
 
 /* Enable Autoreload match interrupt */
 __HAL_LPTIM_ENABLE_IT(hlptim, LPTIM_IT_ARRM);
 
 /* Enable Compare match interrupt */
// __HAL_LPTIM_ENABLE_IT(hlptim, LPTIM_IT_CMPM);
 
 /* Enable the Peripheral */
 __HAL_LPTIM_ENABLE(hlptim);
 
 /* Load the period value in the autoreload register */
 __HAL_LPTIM_AUTORELOAD_SET(hlptim, delay_us * 3);
 
 /* Start timer in freerun mode */
 __HAL_LPTIM_START_CONTINUOUS(hlptim);
}
 
void LPTIM1_SetPWM_us(uint32_t delay_us) { // this delay is the half period
 
 LPTIM_HandleTypeDef* hlptim = &hlptim1;
 
 if((delay_us/3)>0xFFFF) TrapError(); // change the clock prescaler if looking at more than one milisecond
 if(delay_us==0) {
 // turn the timer event off
 __HAL_LPTIM_DISABLE_IT(hlptim, LPTIM_IT_ARRM);
 __HAL_LPTIM_DISABLE(hlptim);
 return; // done
 }
 
 /*HAL_StatusTypeDef*/ HAL_LPTIM_PWM_Start(hlptim, delay_us * 3 * 2, delay_us * 3);
 return;
 
 __HAL_LPTIM_COMPARE_SET(hlptim, delay_us * 3); 
 
 /* Enable Autoreload match interrupt */
//- __HAL_LPTIM_ENABLE_IT(hlptim, LPTIM_IT_ARRM);
 __HAL_LPTIM_DISABLE_IT(hlptim, LPTIM_IT_ARRM);
 
 /* Enable Compare match interrupt */
// __HAL_LPTIM_ENABLE_IT(hlptim, LPTIM_IT_CMPM);
 
 /* Enable the Peripheral */
 __HAL_LPTIM_ENABLE(hlptim);
 
 /* Load the period value in the autoreload register */
 __HAL_LPTIM_AUTORELOAD_SET(hlptim, delay_us * 3 * 2); // it becomes the period
 
 /* Start timer in freerun mode */
 __HAL_LPTIM_START_CONTINUOUS(hlptim);
}
 
/*
void HAL_LPTIM_AutoReloadMatchCallback(LPTIM_HandleTypeDef *hlptim) { 
 // Timer is one shot mode, so it should trigger only once after kitstarted
 NOPs(1);
}
*/
 
 
void LPTIM1_IRQHandler(void) { 
// HAL_LPTIM_IRQHandler(&hlptim1); // ==> HAL_LPTIM_AutoReloadMatchCallback(&hlptim2); 
 
 /* Autoreload match interrupt */
 if(__HAL_LPTIM_GET_FLAG(&hlptim1, LPTIM_FLAG_ARRM) != RESET)
 {
 if(__HAL_LPTIM_GET_IT_SOURCE(&hlptim1, LPTIM_IT_ARRM) != RESET)
 {
 /* Clear Autoreload match flag */
 __HAL_LPTIM_CLEAR_FLAG(&hlptim1, LPTIM_FLAG_ARRM);
 
 /* Autoreload match Callback */
 ...
 }
 }
}

What is the LPTIM clock?

JW