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DAC Signals Generation

Question asked by alarfaj.mohammed on Apr 27, 2015
Latest reply on May 11, 2015 by qwer.asdf
Hi everyone,

I have the STM32L053 Nucleo. I am trying to output a 1.7 V DC using the DAC example code in the stm32cube. The code outputs 6 levels square wave. I want to change the code so it only output a straight DC line of 1.7 volt. I tried to change the code but with no luck. Here is the main.c code posted with this thread. 

Your help is greatly appreciated,


  /**
  ******************************************************************************
  * @file    DAC/DAC_SignalsGeneration/Src/main.c 
  * @author  MCD Application Team
  * @version V1.1.0
  * @date    18-June-2014
  * @brief   This example provides a short description of how to use the DAC 
  *          peripheral to generate several signals.
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2014 STMicroelectronics</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */


/* Includes ------------------------------------------------------------------*/
#include "main.h"




/** @addtogroup STM32L0xx_HAL_Examples
  * @{
  */


/** @addtogroup DAC_SignalsGeneration
  * @{
  */ 


/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
DAC_HandleTypeDef    DacHandle;
static DAC_ChannelConfTypeDef sConfig;
const uint8_t aEscalator8bit[3] = {0x0, 0x66, 0x99};
__IO uint8_t ubSelectedWavesForm = 1;
__IO uint8_t ubKeyPressed = SET; 


/* Private function prototypes -----------------------------------------------*/
static void DAC_Ch1_TriangleConfig(void);
static void DAC_Ch1_EscalatorConfig(void);
static void TIM6_Config(void);
static void SystemClock_Config(void);
static void Error_Handler(void);


/* Private functions ---------------------------------------------------------*/


/**
  * @brief  Main program.
  * @param  None
  * @retval None
  */
int main(void)
{
  /* STM32L0xx HAL library initialization:
       - Configure the Flash prefetch, Flash preread and Buffer caches
       - Systick timer is configured by default as source of time base, but user 
             can eventually implement his proper time base source (a general purpose 
             timer for example or other time source), keeping in mind that Time base 
             duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and 
             handled in milliseconds basis.
       - Low Level Initialization
     */
  HAL_Init();


  /* Configure LED2 */
  BSP_LED_Init(LED2);


  /* Configure the system clock to 2 Mhz */
  SystemClock_Config();


  /* Configures Key Button */
  BSP_PB_Init(BUTTON_KEY, BUTTON_MODE_EXTI);
  
  /*##-1- Configure the DAC peripheral #######################################*/
  DacHandle.Instance = DAC;
  
  /*##-2- Configure the TIM peripheral #######################################*/
  TIM6_Config();
  
  /* Infinite loop */
  while (1)
  {
    /* If the Key is pressed */
    if (ubKeyPressed != RESET)
    {
      HAL_DAC_DeInit(&DacHandle);
      
      /* select waves forms according to the Key Button status */
      if (ubSelectedWavesForm == 1)
      {
        /* The triangle wave has been selected */


        /* Triangle Wave generator -------------------------------------------*/
        DAC_Ch1_TriangleConfig();
      }
      else
      {
        /* The escalator wave has been selected */
         
        /* Escalator Wave generator -------------------------------------------*/
        DAC_Ch1_EscalatorConfig();
      }
      
      ubKeyPressed = RESET; 
    }
  }
}


/**
  * @brief  System Clock Configuration
  *         The system Clock is configured as follow : 
  *            System Clock source            = MSI
  *            SYSCLK(Hz)                     = 2000000
  *            HCLK(Hz)                       = 2000000
  *            AHB Prescaler                  = 1
  *            APB1 Prescaler                 = 1
  *            APB2 Prescaler                 = 1
  *            Flash Latency(WS)              = 0
  *            Main regulator output voltage  = Scale3 mode
  * @param  None
  * @retval None
  */
static void SystemClock_Config(void)
{
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_OscInitTypeDef RCC_OscInitStruct;
  
  /* Enable Power Control clock */
  __PWR_CLK_ENABLE();
  
  /* The voltage scaling allows optimizing the power consumption when the device is 
     clocked below the maximum system frequency, to update the voltage scaling value 
     regarding system frequency refer to product datasheet.  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
  
  /* Enable MSI Oscillator */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_5;
  RCC_OscInitStruct.MSICalibrationValue=0x00;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    /* Initialization Error */
    Error_Handler();
  }
  
  
  /* Select MSI as system clock source and configure the HCLK, PCLK1 and PCLK2 
     clocks dividers */
  RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | 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)
  {
    /* Initialization Error */
    Error_Handler();
  }
}


/**
  * @brief  This function is executed in case of error occurrence.
  * @param  None
  * @retval None
  */
static void Error_Handler(void)
{
    /* Turn LED2 on */
    BSP_LED_On(LED2);
    while(1)
    {
    }
}


static void DAC_Ch1_EscalatorConfig(void)
{
  /*##-1- Initialize the DAC peripheral ######################################*/
  if(HAL_DAC_Init(&DacHandle) != HAL_OK)
  {
    /* Initiliazation Error */
    Error_Handler();
  }
  
  /*##-1- DAC channel1 Configuration #########################################*/
  sConfig.DAC_Trigger = DAC_TRIGGER_T6_TRGO;
  sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;  


  if(HAL_DAC_ConfigChannel(&DacHandle, &sConfig, DACx_CHANNEL1) != HAL_OK)
  {
    /* Channel configuration Error */
    Error_Handler();
  }
  
  /*##-2- Enable DAC Channel1 and associeted DMA #############################*/
  if(HAL_DAC_Start_DMA(&DacHandle, DACx_CHANNEL1, (uint32_t*)aEscalator8bit, 3, DAC_ALIGN_8B_R) != HAL_OK)
  {
    /* Start DMA Error */
    Error_Handler();
  }
}


/**
  * @brief  DAC Channel1 Triangle Configuration
  * @param  None
  * @retval None
  */
static void DAC_Ch1_TriangleConfig(void)
{
  /*##-1- Initialize the DAC peripheral ######################################*/
  if(HAL_DAC_Init(&DacHandle) != HAL_OK)
  {
    /* Initiliazation Error */
    Error_Handler();
  }
  
  /*##-2- DAC channel2 Configuration #########################################*/
  sConfig.DAC_Trigger = DAC_TRIGGER_T6_TRGO;
  sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;  


  if(HAL_DAC_ConfigChannel(&DacHandle, &sConfig, DACx_CHANNEL1) != HAL_OK)
  {
    /* Channel configuartion Error */
    Error_Handler();
  }
  
  /*##-3- DAC channel2 Triangle Wave generation configuration ################*/
  if(HAL_DACEx_TriangleWaveGenerate(&DacHandle, DACx_CHANNEL1, DAC_TRIANGLEAMPLITUDE_1023) != HAL_OK)
  {
    /* Triangle wave generation Error */
    Error_Handler();
  }
  
  /*##-4- Enable DAC Channel1 ################################################*/
  if(HAL_DAC_Start(&DacHandle, DACx_CHANNEL1) != HAL_OK)
  {
    /* Start Error */
    Error_Handler();
  }


  /*##-5- Set DAC channel1 DHR12RD register ################################################*/
  if(HAL_DAC_SetValue(&DacHandle, DACx_CHANNEL1, DAC_ALIGN_12B_R, 0x00) != HAL_OK)
  {
    /* Setting value Error */
    Error_Handler();
  }
}


/**
  * @brief EXTI line detection callbacks
  * @param GPIO_Pin: Specifies the pins connected EXTI line
  * @retval None
  */
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
  /* Change the wave */
    ubKeyPressed = 1;


  /* Change the selected waves forms */
  ubSelectedWavesForm = !ubSelectedWavesForm;
}


/**             
  * @brief  TIM6 Configuration
  * @note   TIM6 configuration is based on APB1 frequency
  * @note   TIM6 Update event occurs each TIM6CLK/256   
  * @param  None
  * @retval None
  */
void TIM6_Config(void)
{
  static TIM_HandleTypeDef  htim;
  TIM_MasterConfigTypeDef sMasterConfig;
  
  /*##-1- Configure the TIM peripheral #######################################*/
  /* Time base configuration */
  htim.Instance = TIM6;
  
  htim.Init.Period = 0x7F;          
  htim.Init.Prescaler = 0;       
  htim.Init.ClockDivision = 0;    
  htim.Init.CounterMode = TIM_COUNTERMODE_UP; 
  HAL_TIM_Base_Init(&htim);
     
  /* TIM6 TRGO selection */
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;


  HAL_TIMEx_MasterConfigSynchronization(&htim, &sMasterConfig);
  
  /*##-2- Enable TIM peripheral counter ######################################*/
  HAL_TIM_Base_Start(&htim);
}
#ifdef  USE_FULL_ASSERT


/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t* file, uint32_t line)

  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */


  /* Infinite loop */
  while (1)
  {
  }
}


#endif


/**
  * @}
  */


/**
  * @}
  */


/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/



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