用STM32控制读取AD7656的转换数据，结果不对~~

只看该作者 · 2011-12-8 08:38

请教各位大侠，我用FPGA自身晶振分频4KHz信号作为AD7656开始转换的信号，然后当BUSY下降沿触发STM32的中断，进入中断后依照以下时序，先置低CS，然后置低RD，读取AD的数据结果，给AD的输入信号是三路0V，和三路2V直流信号，目前能顺利进入中断，但得到的数据完全不对……

时序图如下：

引脚连接如下：
启动AD转换引脚：ADCLK 由FPGA自身晶振分频给出2K/4K/10K Hz（程序调试时，信号不停的给AD）
AD完成BUSY引脚：与STM32普通引脚PA12相连，用来触发中断
AD片选CS引脚：与STM32的FSMC_NE3相连
AD读RD引脚：与STM32的FSMC_NOE相连
AD设置为并行输出，DB0-DB15与STM32的数据总线相连

程序代码如下：

void main(void)
{

SystemInit();  // 晶振初始化系统寄存器初始化
FSMC_SRAM_Init(); //FSMC 总线初始化
   EXIT_Configuration();  //外部中断配置
NVIC_Configuration();  // 嵌套式向量表配置  中断配置需要
   while(1);
}

void EXTI15_10_IRQHandler(void)
{
  if(EXTI_GetITStatus(EXTI_Line12) !=RESET)
  {
u16 i=0;
EXTI_ClearITPendingBit(EXTI_Line12);  /*中断挂起清除*/
GPIO_ResetBits(GPIOG,GPIO_Pin_10); /*片选CS置低*/
Delay(20);
for(i=0;i<6;i++)
{
GPIO_ResetBits(GPIOD,GPIO_Pin_4); /*RD置低*/
Delay(10);
buf=*(u16 *)(0x68000000+i*1);  /*这行和下一行用来对比*/
buftemp=*(u16 *)(0x68000000);
Delay(10);
GPIO_SetBits(GPIOD,GPIO_Pin_4);
}
GPIO_SetBits(GPIOG,GPIO_Pin_10);

Delay(10);
  }
}

void FSMC_SRAM_Init(void)
{
  FSMC_NORSRAMInitTypeDef  FSMC_NORSRAMInitStructure;
  FSMC_NORSRAMTimingInitTypeDef  p;
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_FSMC, ENABLE);  //FSMC总线初始化使能

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOG | RCC_APB2Periph_GPIOE |
                     RCC_APB2Periph_GPIOF | RCC_APB2Periph_AFIO, ENABLE);

  GPIO_SetBits(GPIOD,GPIO_Pin_4);

/*-- GPIO Configuration ------------------------------------------------------*/
  /* SRAM Data lines configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_8 | GPIO_Pin_9 |
                              GPIO_Pin_10 | GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOD, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 |
                              GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 |
                              GPIO_Pin_15;
  GPIO_Init(GPIOE, &GPIO_InitStructure);

  /* SRAM Address lines configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 |
                              GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_12 | GPIO_Pin_13 |
                              GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_Init(GPIOF, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 |
                              GPIO_Pin_4 | GPIO_Pin_5;
  GPIO_Init(GPIOG, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13;
  GPIO_Init(GPIOD, &GPIO_InitStructure);

  /* NOE and NWE configuration */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_Init(GPIOD, &GPIO_InitStructure);

  /* NE3 configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_Init(GPIOG, &GPIO_InitStructure);
  GPIO_SetBits(GPIOG,GPIO_Pin_10);

/* GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
  GPIO_Init(GPIOD, &GPIO_InitStructure);  */

  /* NBL0, NBL1 configuration */
/*  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
  GPIO_Init(GPIOE, &GPIO_InitStructure);

/*-- FSMC Configuration ------------------------------------------------------*/
p.FSMC_AddressSetupTime = 1;
  p.FSMC_AddressHoldTime = 0;
  p.FSMC_DataSetupTime = 2;
  p.FSMC_BusTurnAroundDuration = 0;
  p.FSMC_CLKDivision = 0;
  p.FSMC_DataLatency = 0;
  p.FSMC_AccessMode = FSMC_AccessMode_A;


  FSMC_NORSRAMInitStructure.FSMC_Bank = FSMC_Bank1_NORSRAM3;
  FSMC_NORSRAMInitStructure.FSMC_DataAddressMux = FSMC_DataAddressMux_Disable;
  FSMC_NORSRAMInitStructure.FSMC_MemoryType = FSMC_MemoryType_SRAM;
  FSMC_NORSRAMInitStructure.FSMC_MemoryDataWidth = FSMC_MemoryDataWidth_16b;
  FSMC_NORSRAMInitStructure.FSMC_BurstAccessMode = FSMC_BurstAccessMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalPolarity = FSMC_WaitSignalPolarity_Low;
  FSMC_NORSRAMInitStructure.FSMC_WrapMode = FSMC_WrapMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalActive = FSMC_WaitSignalActive_BeforeWaitState;
  FSMC_NORSRAMInitStructure.FSMC_WriteOperation = FSMC_WriteOperation_Enable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignal = FSMC_WaitSignal_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ExtendedMode = FSMC_ExtendedMode_Disable;
  //FSMC_NORSRAMInitStructure.FSMC_AsyncWait = FSMC_AsyncWait_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WriteBurst = FSMC_WriteBurst_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ReadWriteTimingStruct = &p;
  FSMC_NORSRAMInitStructure.FSMC_WriteTimingStruct = &p;

  FSMC_NORSRAMInit(&FSMC_NORSRAMInitStructure);

  /* Enable FSMC Bank1_SRAM Bank */
  FSMC_NORSRAMCmd(FSMC_Bank1_NORSRAM3, ENABLE);
}

void EXIT_Configuration(void)
{
  EXTI_InitTypeDef EXTI_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;  /*PA12-busy*/
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_EXTILineConfig(GPIO_PortSourceGPIOA,GPIO_PinSource12);
  EXTI_ClearITPendingBit(EXTI_Line12);
  EXTI_InitStructure.EXTI_Line = EXTI_Line12;
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling; //下降沿为触发
  EXTI_InitStructure.EXTI_LineCmd = ENABLE;
  EXTI_Init(&EXTI_InitStructure);

}

void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;

/* Configure one bit for preemption priority */
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3);

  /* Enable the EXTI9_5 Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel =  EXTI15_10_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}