Solved
STM32l475RC - TIM3 configuration when running in low power mode
Hi,
in my Project I need a millisecond timer. Therefore I try to use TIM3. Now I have the following problem.
For example, when the MCU runs in Run-Mode at 80 MHz TIM3 fires every 1 ms according to its configuration. But when the MCU runs in low power mode at 2 MHz, TIM3 fires at a too low frequency (around a factor of 3). After studying the datasheet and testing around with the configuration, I have no idea what it is. I think the configuration should be ok.
What am I doing wrong? Does somebody has any idea?
Here is my configuration of the system clocks.
void g_system_clock_config_lowpower(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
// Reset the RCC clock configuration to the default reset state.
HAL_RCC_DeInit();
/** Configure LSE Drive Capability
*/
HAL_PWR_EnableBkUpAccess();
__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE|RCC_OSCILLATORTYPE_MSI;
RCC_OscInitStruct.LSEState = RCC_LSE_ON;
RCC_OscInitStruct.MSIState = RCC_MSI_ON;
RCC_OscInitStruct.MSICalibrationValue = 0;
RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_5;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
Error_Handler();
}
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_LPUART1
|RCC_PERIPHCLK_I2C1|RCC_PERIPHCLK_ADC;
PeriphClkInit.Lpuart1ClockSelection = RCC_LPUART1CLKSOURCE_SYSCLK;
PeriphClkInit.I2c1ClockSelection = RCC_I2C1CLKSOURCE_SYSCLK;
PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_SYSCLK;
PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
/** Configure the main internal regulator output voltage
*/
if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
{
Error_Handler();
}
/** Enable MSI Auto calibration
*/
HAL_RCCEx_EnableMSIPLLMode();
/* Update SystemCoreClock variable */
SystemCoreClockUpdate();
}And this is my configuration of TIM3.
void MX_TIM3_Init(void)
{
TIM_ClockConfigTypeDef sClockSourceConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
uint32_t uwPrescalerValue = (uint32_t)(SystemCoreClock / 100000) - 1; // to 100 kHz
uint32_t period = 100-1; // to 1 kHz -> 1/1000s = 0.001s
htim3.Instance = TIM3;
htim3.Init.Prescaler = uwPrescalerValue;
htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
htim3.Init.Period = period;
htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_Base_Init(&htim3) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
}Thanks in advance,
Marco.