@par Example Description
How to use the DAC peripheral to generate several signals using the DMA controller.
For each press on User push-button, a signal has been selected and can be monitored on
the DAC channel one:
- Triangle waveform (Channel 1).
- Escalator waveform (Channel 1) using DMA transfer.
STM32746G-DISCOVERY board's LED can be used to monitor the process status:
- LED1 is slowly blinking (1 sec. period) and example is stopped (using infinite loop)
when there is an error during process.
@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
@note The application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Analog, DAC, Signals generation, DMA, Triangle, Escalator, Waveform, Amplitude
@Note If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
The address and the size of cacheable buffers (shared between CPU and other masters) must be properly updated to be aligned to cache line size (32 bytes).
@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
Even though the user must manage the cache coherence for read accesses.
Please refer to the AN4838 “Managing memory protection unit (MPU) in STM32 MCUs”
Please refer to the AN4839 “Level 1 cache on STM32F7 Series”
1. main.h
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __MAIN_H
#define __MAIN_H
/* Includes ------------------------------------------------------------------*/
#include "stm32f7xx_hal.h"
#include "stm32746g_discovery.h"
/* Exported types ------------------------------------------------------------*/
/* Exported constants --------------------------------------------------------*/
/* User can use this section to tailor DACx instance used and associated resources */
/* Definition for DACx clock resources */
#define DACx DAC
#define DACx_CHANNEL_GPIO_CLK_ENABLE() __HAL_RCC_GPIOA_CLK_ENABLE()
#define DMAx_CLK_ENABLE() __HAL_RCC_DMA1_CLK_ENABLE()
#define DACx_CLK_ENABLE() __HAL_RCC_DAC_CLK_ENABLE()
#define DACx_FORCE_RESET() __HAL_RCC_DAC_FORCE_RESET()
#define DACx_RELEASE_RESET() __HAL_RCC_DAC_RELEASE_RESET()
/* Definition for DACx Channel Pin */
#define DACx_CHANNEL_PIN GPIO_PIN_4
#define DACx_CHANNEL_GPIO_PORT GPIOA
/* Definition for DACx's Channel */
#define DACx_DMA_CHANNEL DMA_CHANNEL_7
#define DACx_CHANNEL DAC_CHANNEL_1
/* Definition for DACx's DMA_STREAM */
#define DACx_DMA_INSTANCE DMA1_Stream5
/* Definition for DACx's NVIC */
#define DACx_DMA_IRQn DMA1_Stream5_IRQn
#define DACx_DMA_IRQHandler DMA1_Stream5_IRQHandler
/* Exported macro ------------------------------------------------------------*/
/* Exported functions ------------------------------------------------------- */
#endif /* __MAIN_H */
2.main.c
DAC_HandleTypeDef DacHandle;
static DAC_ChannelConfTypeDef sConfig;
const uint8_t aEscalator8bit[6] = {0x0, 0x33, 0x66, 0x99, 0xCC, 0xFF};
__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);
void SystemClock_Config(void);
static void Error_Handler(void);
static void CPU_CACHE_Enable(void);
/* Private functions ---------------------------------------------------------*/
/**
* @brief Main program.
* @param None
* @retval None
*/
int main(void)
{
/* Enable the CPU Cache */
CPU_CACHE_Enable();
/* STM32F7xx HAL library initialization:
- Configure the Flash prefetch
- 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.
- Set NVIC Group Priority to 4
- Low Level Initialization
*/
HAL_Init();
/* Configure the system clock to 216 MHz */
SystemClock_Config();
/* Configure LED1 */
BSP_LED_Init(LED1);
/* Configures User push-button */
BSP_PB_Init(BUTTON_KEY, BUTTON_MODE_EXTI);
/*##-1- Configure the DAC peripheral #######################################*/
DacHandle.Instance = DACx;
/*##-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 User push-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 = PLL (HSE)
* SYSCLK(Hz) = 216000000
* HCLK(Hz) = 216000000
* AHB Prescaler = 1
* APB1 Prescaler = 4
* APB2 Prescaler = 2
* HSE Frequency(Hz) = 25000000
* PLL_M = 25
* PLL_N = 432
* PLL_P = 2
* PLL_Q = 9
* VDD(V) = 3.3
* Main regulator output voltage = Scale1 mode
* Flash Latency(WS) = 7
* @param None
* @retval None
*/
void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitTypeDef RCC_OscInitStruct;
HAL_StatusTypeDef ret = HAL_OK;
/* Enable HSE Oscillator and activate PLL with HSE as source */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 432;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 9;
ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Activate the OverDrive to reach the 216 MHz Frequency */
ret = HAL_PWREx_EnableOverDrive();
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Select PLL 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_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7);
if(ret != HAL_OK)
{
while(1) { ; }
}
}
/**
* @brief This function is executed in case of error occurrence.
* @param None
* @retval None
*/
static void Error_Handler(void)
{
/* Error if LED1 is slowly blinking (1 sec. period) */
while(1)
{
BSP_LED_Toggle(LED1);
HAL_Delay(1000);
}
}
static void DAC_Ch1_EscalatorConfig(void)
{
/*##-1- Initialize the DAC peripheral ######################################*/
if (HAL_DAC_Init(&DacHandle) != HAL_OK)
{
/* Initialization 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_CHANNEL) != HAL_OK)
{
/* Channel configuration Error */
Error_Handler();
}
/*##-2- Enable DAC selected channel and associated DMA #############################*/
if (HAL_DAC_Start_DMA(&DacHandle, DACx_CHANNEL, (uint32_t *)aEscalator8bit, 6, 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)
{
/* DAC initialization 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_CHANNEL) != HAL_OK)
{
/* Channel configuration Error */
Error_Handler();
}
/*##-3- DAC channel2 Triangle Wave generation configuration ################*/
if (HAL_DACEx_TriangleWaveGenerate(&DacHandle, DACx_CHANNEL, DAC_TRIANGLEAMPLITUDE_1023) != HAL_OK)
{
/* Triangle wave generation Error */
Error_Handler();
}
/*##-4- Enable DAC Channel1 ################################################*/
if (HAL_DAC_Start(&DacHandle, DACx_CHANNEL) != HAL_OK)
{
/* Start Error */
Error_Handler();
}
/*##-5- Set DAC channel1 DHR12RD register ################################################*/
if (HAL_DAC_SetValue(&DacHandle, DACx_CHANNEL, DAC_ALIGN_12B_R, 0x100) != 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 = 0x7FF;
htim.Init.Prescaler = 0;
htim.Init.ClockDivision = 0;
htim.Init.CounterMode = TIM_COUNTERMODE_UP;
htim.Init.RepetitionCounter = 0;
htim.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
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);
}
/**
* @brief CPU L1-Cache enable.
* @param None
* @retval None
*/
static void CPU_CACHE_Enable(void)
{
/* Enable I-Cache */
SCB_EnableICache();
/* Enable D-Cache */
SCB_EnableDCache();
}
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