用示波器看不到应有的波形

2万 · 2015-9-24 18:37

我用系统的示例工程“Filter_ADC_VDAC Example Project”做数字滤波然后用示波器看结果该示例工程很方便先赞一个

然后我把ADC设置成16位但只看最重要的8位信号的DAC转换对main.c里的中断作如下修改
原中断
CY_ISR(filterVDAC)
{
/* Convert the 2's complement value to an unsigned 8-bit value
   * The VDAC expects an unsigned 8-bit value as input.
   */
      VDAC8_SetValue(Filter_Read8(Filter_CHANNEL_A) + 128u);
}

我的修改
CY_ISR(filterVDAC)
{
/* Convert the 2's complement value to an unsigned 8-bit value
   * The VDAC expects an unsigned 8-bit value as input.
   */
      uint8 test;
      test=(Filter_Read16(Filter_CHANNEL_A)>>8);
      VDAC8_SetValue(test + 128u);
}
但是下到板子上用示波器看不到应有的波形啊
到底是哪里有问题？！！求救啊！！

2万 · 2015-9-24 18:37

试一下这个程序：
/******************************************************************************/
#include <device.h>
#include <VDAC8.h>

#define REQUEST_PER_BURST       (1u)
#define BYTES_PER_BURST       (2u)
#define UPPER_SRC_ADDRESS       CYDEV_PERIPH_BASE
#define UPPER_DEST_ADDRESS    CYDEV_PERIPH_BASE

void DMA_Config(void);

CY_ISR(filterVDAC)
{

      VDAC8_SetValue((uint8)(Filter_Read16(Filter_CHANNEL_A)>>8));

}

void main()
{
/* Start all components used on schematic */
ADC_DelSig_IRQ_Start();
isr_StartEx(filterVDAC);
ADC_DelSig_Start();
ADC_DelSig_StartConvert();
VDAC8_Start();
Opamp_Start();
Filter_Start();
      Filter_DALIGN_REG = 0x00;
      Filter_SetCoherency(Filter_CHANNEL_A, Filter_KEY_LOW);

/* User-implemented function to set-up DMA */
DMA_Config();

/* Enable Global Interrupts */
CYGlobalIntEnable;

for(;;)
{
}
} /* End of main */

void DMA_Config(void)
{
/* Declare variable to hold the handle for DMA channel */
uint8 channelHandle;
uint8 tdChanA;
channelHandle = DMA_DmaInitialize(BYTES_PER_BURST, REQUEST_PER_BURST,
                                    HI16(UPPER_SRC_ADDRESS), HI16(UPPER_DEST_ADDRESS));
tdChanA = CyDmaTdAllocate();
CyDmaTdSetConfiguration(tdChanA, 2u, DMA_INVALID_TD, 0u);
CyDmaTdSetAddress(tdChanA, LO16((uint32)ADC_DelSig_DEC_SAMP_PTR), LO16((uint32)Filter_STAGEA_PTR));
CyDmaChSetInitialTd(channelHandle, tdChanA);

CyDmaChEnable(channelHandle, 1u);
}

/* [] END OF FILE */
/*************************************************************************************/

2万 · 2015-9-24 18:38

我用你这个程序试了一下还是不行啊从示波器看不到正常输出实际上是什么输出都没有

2万 · 2015-9-24 18:38

是不是哪里还要改啊？

2万 · 2015-9-24 18:38

ADC和DAC分开验证不就简单了

2万 · 2015-9-24 18:39

哦，也是