STM32L053 timer modul for waveform generation

[fabian23]

Posted on August 12, 2015 at 09:35

Good morning everbody,

I am currently using a STM32L053C8 and I want to generate a square waveform. My APBx timer clock is 8MHz and can't be rised. Is it possible to generate a 8 MHz squrae waveform at this APBx timer clock or what is the maximum waveform frequency at this timer clock? I am currently only getting a 2 MHz square waveform with the clock and timer config below an I hope that I missed a prescaler or something.

void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct;
__PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = 16;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
HAL_RCC_OscConfig(&RCC_OscInitStruct);
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV2;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0);
HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI, RCC_MCODIV_2);
HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/8000);
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK_DIV8);
}
void ConfigTimerOut(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
TIM_Base_InitTypeDef TIM_BaseInitStruct;
TIM_OC_InitTypeDef TIM_OCInitStruct;
TIM_HandleTypeDef TIM_HandleStruct;
TIM_ClockConfigTypeDef TIM_ClockConfigStruct;
TIM_MasterConfigTypeDef TIM_MasterConfigStruct;
__TIM21_CLK_ENABLE();
__GPIOB_CLK_ENABLE();
GPIO_InitStruct.Pin = GPIO_PIN_13;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF6_TIM21;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
TIM_BaseInitStruct.ClockDivision = TIM_CLOCKDIVISION_DIV1;
TIM_BaseInitStruct.CounterMode = TIM_COUNTERMODE_UP;
TIM_BaseInitStruct.Period = 1;
TIM_BaseInitStruct.Prescaler = 0;
TIM_OCInitStruct.OCMode = TIM_OCMODE_TOGGLE;
TIM_OCInitStruct.OCPolarity = TIM_OCPOLARITY_HIGH;
TIM_OCInitStruct.OCFastMode = TIM_OCFAST_DISABLE;
TIM_OCInitStruct.Pulse = 0;
TIM_HandleStruct.Init = TIM_BaseInitStruct;
TIM_HandleStruct.Instance = TIM21;
TIM_HandleStruct.Channel = HAL_TIM_ACTIVE_CHANNEL_1;
TIM_ClockConfigStruct.ClockPolarity = TIM_CLOCKPOLARITY_BOTHEDGE;
TIM_ClockConfigStruct.ClockPrescaler = TIM_CLOCKPRESCALER_DIV1;
TIM_ClockConfigStruct.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
TIM_MasterConfigStruct.MasterOutputTrigger = TIM_TRGO_ENABLE;
TIM_MasterConfigStruct.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
HAL_TIM_Base_Init(&TIM_HandleStruct);
HAL_TIM_OC_ConfigChannel(&TIM_HandleStruct,&TIM_OCInitStruct,TIM_CHANNEL_1);
HAL_TIM_ConfigClockSource(&TIM_HandleStruct,&TIM_ClockConfigStruct);
HAL_TIMEx_MasterConfigSynchronization(&TIM_HandleStruct,&TIM_MasterConfigStruct);
TIM21->CCER |= TIM_CCER_CC1E; /* (5)*/
TIM21->BDTR |= TIM_BDTR_MOE; /* (6) */
TIM21->CR1 |= TIM_CR1_CEN; /* (7) */
}