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新手上路，想请教各位前辈，我用STM32F103ZET6的板子，用片内DA产生正弦波的实验，调用SystemInit()最大电压只能达到2.12V, 而不使用SystemInit()函数则一切正常，峰峰值电压可达3.28.。
这是为什么啊？？难道 系统频率会影响DA输出?? 为何 不使用SystemInit(),也不使用RCC初始化时钟，系统也可以运行？？
程序如下：
/* Includes ------------------------------------------------------------------*/
#include "stm32f10x.h"
/** @addtogroup STM32F10x_StdPeriph_Examples
* @{
*/
/** @addtogroup DAC_DualModeDMA_SineWave
* @{
*/
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
#define DAC_DHR12RD_Address 0x40007420
/* Init Structure definition */
DAC_InitTypeDef DAC_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
const uint16_t Sine12bit[32] = {
2047, 2447, 2831, 3185, 3498, 3750, 3939, 4056, 4095, 4056,
3939, 3750, 3495, 3185, 2831, 2447, 2047, 1647, 1263, 909,
599, 344, 155, 38, 0, 38, 155, 344, 599, 909, 1263, 1647};
uint32_t DualSine12bit[32];
uint8_t Idx = 0;
/* Private function prototypes -----------------------------------------------*/
void RCC_Configuration(void);
void GPIO_Configuration(void);
void Delay(__IO uint32_t nCount);
int main(void)
{
SystemInit(); //关键所在
/* System Clocks Configuration */
RCC_Configuration();
/* Once the DAC channel is enabled, the corresponding GPIO pin is automatically
connected to the DAC converter. In order to avoid parasitic consumption,
the GPIO pin should be configured in analog */
GPIO_Configuration();
/* TIM2 Configuration */
/* Time base configuration */
TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
TIM_TimeBaseStructure.TIM_Period = 0x19;
TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
/* TIM2 TRGO selection */
TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);
/* DAC channel1 Configuration */
DAC_InitStructure.DAC_Trigger = DAC_Trigger_T2_TRGO;
DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable;
DAC_Init(DAC_Channel_1, &DAC_InitStructure);
/* DAC channel2 Configuration */
DAC_Init(DAC_Channel_2, &DAC_InitStructure);
/* Fill Sine32bit table */
for (Idx = 0; Idx < 32; Idx++)
{
DualSine12bit[Idx] = (Sine12bit[Idx] << 16) + (Sine12bit[Idx]);
}
DMA_DeInit(DMA2_Channel4);
DMA_InitStructure.DMA_PeripheralBaseAddr = DAC_DHR12RD_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&DualSine12bit;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
DMA_InitStructure.DMA_BufferSize = 32;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA2_Channel4, &DMA_InitStructure);
/* Enable DMA2 Channel4 */
DMA_Cmd(DMA2_Channel4, ENABLE);
/* Enable DAC Channel1: Once the DAC channel1 is enabled, PA.04 is
automatically connected to the DAC converter. */
DAC_Cmd(DAC_Channel_1, ENABLE);
/* Enable DAC Channel2: Once the DAC channel2 is enabled, PA.05 is
automatically connected to the DAC converter. */
DAC_Cmd(DAC_Channel_2, ENABLE);
/* Enable DMA for DAC Channel2 */
DAC_DMACmd(DAC_Channel_2, ENABLE);
/* TIM2 enable counter */
TIM_Cmd(TIM2, ENABLE);
while (1)
{
}
}
/**
* @brief Configures the different system clocks.
* @param None
* @retval None
*/
void RCC_Configuration(void)
{
/* Enable peripheral clocks ------------------------------------------------*/
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2, ENABLE);
/* GPIOA Periph clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
/* DAC Periph clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
/* TIM2 Periph clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
}
/**
* @brief Configures the different GPIO ports.
* @param None
* @retval None
*/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Once the DAC channel is enabled, the corresponding GPIO pin is automatically
connected to the DAC converter. In order to avoid parasitic consumption,
the GPIO pin should be configured in analog */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
/**
* @brief Inserts a delay time.
* @param nCount: specifies the delay time length.
* @retval None
*/
void Delay(__IO uint32_t nCount)
{
for(; nCount != 0; nCount--);
}
#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 2010 STMicroelectronics *****END OF FILE****/
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发表于 2013-7-16 14:48:42
发表于 2013-7-16 21:36:47
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