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使用ADS7865与DSP28335配合进行双通道信号采集，输入端接地后用CCS调试，采集数据结果为随机数，为什么？


  • 我使用ADS7865与DSP28335配合进行双通道信号采集，现输入端接地后用CCS调试，采集数据结果为随机数，怀疑是程序时序问题，但不知道具体问题在哪里。
    ADS7865采用32M外部有源晶振，CS#管脚接地，RD#WR#分别连接DSP28335XINTF的XRDn、XWE0n，BUSY管脚连接DSP28335的16管脚（GPIO7/EPWM4B/MCLKRA/ECAP2），CONVST#管脚连接有问题，连接的DSP28335的152管脚（GPIO41/XA1），在使用XINTF模块时只能作为地址线，所以程序中用写地址来对CONVST进行置高置低。
    现调试配置ADS7865内部DAC参考电压，发现可以成功配置，排除了读写方式的问题。
    器件原理图及晶振波形图见附件。
    AD程序如下，输入管脚接地，数据为随机数：
    #include "DSP28x_Project.h" // Device Headerfile and Examples Include File
    #define LED GpioDataRegs.GPADAT.bit.GPIO20 // Basic pinout configuration example

    // Configure the period for AD
    Uint16 *add = (Uint16 *) 0x200002;
    Uint16 temp;

    //==============================================================================================
    interrupt void epwm1_timer_isr(void);
    void Init_epwm1_timer(void);
    void init_zone7(void);
    void init_Gpio(void);
    //==============================================================================================
    Uint16 VoltageA[5];
    Uint16 VoltageB[5];
    void main(void)
    {
    Uint16 i=0,k=0;
    for(i=0;i<5;i++)
    {
    VoltageA=0;
    VoltageB=0;
    }
    // Step 1. Initialize System Control:
    // PLL, WatchDog, enable Peripheral Clocks
    // This example function is found in the DSP2833x_SysCtrl.c file.
    InitSysCtrl();
    // Step 2. Initialize GPIO:
    // This example function is found in the DSP2833x_Gpio.c file and
    // illustrates how to set the GPIO to it's default state.
    // InitGpio(); Skipped for this example
    // Step 3. Clear all interrupts and initialize PIE vector table:
    // Disable CPU interrupts
    DINT;
    // Initialize PIE control registers to their default state.
    // The default state is all PIE interrupts disabled and flags
    // are cleared.
    // This function is found in the DSP2833x_PieCtrl.c file.
    InitPieCtrl();
    // Disable CPU interrupts and clear all CPU interrupt flags:
    IER = 0x0000;
    IFR = 0x0000;
    // Initialize the PIE vector table with pointers to the shell Interrupt
    // Service Routines (ISR).
    // This will populate the entire table, even if the interrupt
    // is not used in this example. This is useful for debug purposes.
    // The shell ISR routines are found in DSP2833x_DefaultIsr.c.
    // This function is found in DSP2833x_PieVect.c.
    InitPieVectTable();
    EALLOW; // This is needed to write to EALLOW protected registers
    // PieVectTable.EPWM1_INT = &epwm1_timer_isr;
    EDIS; // This is needed to disable write to EALLOW protected registers
    // Step 4. Initialize all the Device Peripherals:
    // This function is found in DSP2833x_InitPeripherals.c
    // InitPeripherals(); // Not required for this example
    // Init_epwm1_timer(); // For this example, only initialize the ePWM Timers
    // Step 5. User specific code:
    // This example is a basic pinout
    init_Gpio();
    init_zone7();
    // IER |= M_INT3;
    // Enable EPWM INTn in the PIE: Group 3 interrupt 1-6
    // PieCtrlRegs.PIEIER3.bit.INTx1 = 1;
    // Enable global Interrupts and higher priority real-time debug events:
    EINT; // Enable Global interrupt INTM
    ERTM; // Enable Global realtime interrupt DBGM
    // Step 6. IDLE loop. Just sit and loop forever (optional):
    i=0;
    while(GpioDataRegs.GPADAT.bit.GPIO7 !=0){}//ABUSY
    *add=0x1000; //指令 0x100h,,,CONVST=1;
    // temp=*(add);
    for(k=0;k<10;k++)
    {
    temp=*(add-2); //CONVST=0; 启动保持 和 转换 上一次结果
    }
    while(GpioDataRegs.GPADAT.bit.GPIO7 !=0){}
    temp=*(add); //CONVST=1; 启动保持 和 转换
    for(;;)
    {
    for(k=0;k<10;k++)
    {
    temp=*(add-2); //CONVST=0; 启动保持 和 转换 上一次结果
    }
    while(GpioDataRegs.GPADAT.bit.GPIO7 !=0){}
    VoltageA=(*add >>4);
    for(k=0;k<10;k++) ;
    VoltageB[i++]=(*add >>4);
    if(i==5)
    i=0;
    }
    }
    void Init_epwm1_timer()
    {
    EALLOW;
    SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 0; // Stop all the TB clocks
    EDIS;
    // Setup Sync
    //EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
    // Allow each timer to be sync'ed

    //EPwm1Regs.TBCTL.bit.HSPCLKDIV=3;
    //EPwm1Regs.TBCTL.bit.CLKDIV=1; //epwm1clk=1/12*systemclk
    EPwm1Regs.TBCTL.bit.HSPCLKDIV=3;
    EPwm1Regs.TBCTL.bit.CLKDIV=0; //epwm1clk=1/6*systemclk

    EPwm1Regs.TBPRD = 50000/10;
    EPwm1Regs.TBCTL.bit.CTRMODE = 0; // Count up
    EPwm1Regs.ETSEL.bit.INTSEL = 2; // Select INT on Zero event
    EPwm1Regs.ETSEL.bit.INTEN = 1; // Enable INT
    EPwm1Regs.ETPS.bit.INTPRD = 1; // Generate INT on 1st event
    EALLOW;
    SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1; // Start all the timers synced
    EDIS;
    }

    // Interrupt routines uses in this example
    interrupt void epwm1_timer_isr(void)
    {
    LED=~LED;
    *add=0x0000;
    // while(GpioCtrlRegs.GPADAT.bit.GPIO7 !=0) { }//ABUSY
    // Check against sent data
    /* temp=*add;
    voltageA[count]=temp>>4;
    temp=*add;
    voltageB[count]=temp>>4;
    Count=Count+1;
    if (Count>=500) //end of an interrogation
    {
    Count=0;
    }*/
    //====================================================================
    // Clear INT flag for this timer
    EPwm1Regs.ETCLR.bit.INT = 1;
    // Acknowledge this interrupt to receive more interrupts from group 3
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
    }
    void init_Gpio(void)
    {
    EALLOW;
    GpioCtrlRegs.GPAMUX1.bit.GPIO7 = 0; // GPIO7 ABUSY
    GpioCtrlRegs.GPADIR.bit.GPIO7 = 0; // GPIO7 = input
    GpioCtrlRegs.GPAMUX2.bit.GPIO20 = 0; // GPIO20
    GpioCtrlRegs.GPADIR.bit.GPIO20 = 1; // GPIO20 = output
    EDIS;
    }
    void init_zone7(void)
    {
    // Make sure the XINTF clock is enabled
    SysCtrlRegs.PCLKCR3.bit.XINTFENCLK = 1;
    // Configure the GPIO for XINTF with a 16-bit data bus
    // This function is in DSP2833x_Xintf.c
    InitXintf16Gpio();
    EALLOW;
    // All Zones---------------------------------
    // Timing for all zones based on XTIMCLK = SYSCLKOUT
    XintfRegs.XINTCNF2.bit.XTIMCLK = 0;
    // Buffer up to 3 writes
    XintfRegs.XINTCNF2.bit.WRBUFF = 3;
    // XCLKOUT is enabled
    XintfRegs.XINTCNF2.bit.CLKOFF = 0;
    // XCLKOUT = XTIMCLK
    XintfRegs.XINTCNF2.bit.CLKMODE = 0;
    // Disable XHOLD to prevent XINTF bus from going into high impedance state
    // whenever TZ3 signal goes low. This occurs because TZ3 on GPIO14 is
    // shared with HOLD of XINTF
    XintfRegs.XINTCNF2.bit.HOLD = 1;
    // Zone 7------------------------------------
    // When using ready, ACTIVE must be 1 or greater
    // Lead must always be 1 or greater
    // Zone write timing
    XintfRegs.XTIMING7.bit.XWRLEAD = 1;
    XintfRegs.XTIMING7.bit.XWRACTIVE = 2;
    XintfRegs.XTIMING7.bit.XWRTRAIL = 1;
    // Zone read timing
    XintfRegs.XTIMING7.bit.XRDLEAD = 1;
    XintfRegs.XTIMING7.bit.XRDACTIVE = 3;
    XintfRegs.XTIMING7.bit.XRDTRAIL = 0;
    // don't double all Zone read/write lead/active/trail timing
    XintfRegs.XTIMING7.bit.X2TIMING = 0;
    // Zone will not sample XREADY signal
    XintfRegs.XTIMING7.bit.USEREADY = 0;
    XintfRegs.XTIMING7.bit.READYMODE = 0;
    // 1,1 = x16 data bus
    // 0,1 = x32 data bus
    // other values are reserved
    XintfRegs.XTIMING7.bit.XSIZE = 3;
    EDIS;
    //Force a pipeline flush to ensure that the write to
    //the last register configured occurs before returning.
    __asm(" RPT #7 || NOP");
    }

    //===========================================================================
    // No more.
    //===========================================================================
    配置参考电压程序如下，测量得REFOUT电压正确改变：
    #include "DSP28x_Project.h" // Device Headerfile and Examples Include File

    // Configure the period for AD
    Uint16 *add = (Uint16 *) 0x200002;
    Uint16 temp;

    //==============================================================================================
    interrupt void epwm1_timer_isr(void);
    void Init_epwm1_timer(void);
    void init_zone7(void);
    void init_Gpio(void);
    //==============================================================================================
    void main(void)
    {
    Uint16 k=0;
    // Step 1. Initialize System Control:
    // PLL, WatchDog, enable Peripheral Clocks
    // This example function is found in the DSP2833x_SysCtrl.c file.
    InitSysCtrl();
    // Step 2. Initialize GPIO:
    // This example function is found in the DSP2833x_Gpio.c file and
    // illustrates how to set the GPIO to it's default state.
    // InitGpio(); Skipped for this example
    // Step 3. Clear all interrupts and initialize PIE vector table:
    // Disable CPU interrupts
    DINT;
    // Initialize PIE control registers to their default state.
    // The default state is all PIE interrupts disabled and flags
    // are cleared.
    // This function is found in the DSP2833x_PieCtrl.c file.
    InitPieCtrl();
    // Disable CPU interrupts and clear all CPU interrupt flags:
    IER = 0x0000;
    IFR = 0x0000;
    // Initialize the PIE vector table with pointers to the shell Interrupt
    // Service Routines (ISR).
    // This will populate the entire table, even if the interrupt
    // is not used in this example. This is useful for debug purposes.
    // The shell ISR routines are found in DSP2833x_DefaultIsr.c.
    // This function is found in DSP2833x_PieVect.c.
    InitPieVectTable();
    EALLOW; // This is needed to write to EALLOW protected registers
    // PieVectTable.EPWM1_INT = &epwm1_timer_isr;
    EDIS; // This is needed to disable write to EALLOW protected registers
    // Step 4. Initialize all the Device Peripherals:
    // This function is found in DSP2833x_InitPeripherals.c
    // InitPeripherals(); // Not required for this example
    // Init_epwm1_timer(); // For this example, only initialize the ePWM Timers
    // Step 5. User specific code:
    // This example is a basic pinout
    init_Gpio();
    init_zone7();
    // IER |= M_INT3;
    // Enable EPWM INTn in the PIE: Group 3 interrupt 1-6
    // PieCtrlRegs.PIEIER3.bit.INTx1 = 1;
    // Enable global Interrupts and higher priority real-time debug events:
    EINT; // Enable Global interrupt INTM
    ERTM; // Enable Global realtime interrupt DBGM
    // Step 6. IDLE loop. Just sit and loop forever (optional):
    while(GpioDataRegs.GPADAT.bit.GPIO7 !=0){}
    *add=0x1010; //指令 0x101h
    *add=0x1FD0; //DAC1.240V
    for(k=0;k<10;k++) ;
    *add=0x1030; //指令 0x103h
    *add=0x1FD0; //DAC1.240V
    for(;;)
    {
    }
    }
    void Init_epwm1_timer()
    {
    EALLOW;
    SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 0; // Stop all the TB clocks
    EDIS;
    // Setup Sync
    //EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
    // Allow each timer to be sync'ed

    //EPwm1Regs.TBCTL.bit.HSPCLKDIV=3;
    //EPwm1Regs.TBCTL.bit.CLKDIV=1; //epwm1clk=1/12*systemclk
    EPwm1Regs.TBCTL.bit.HSPCLKDIV=3;
    EPwm1Regs.TBCTL.bit.CLKDIV=0; //epwm1clk=1/6*systemclk

    EPwm1Regs.TBPRD = 50000/10;
    EPwm1Regs.TBCTL.bit.CTRMODE = 0; // Count up
    EPwm1Regs.ETSEL.bit.INTSEL = 2; // Select INT on Zero event
    EPwm1Regs.ETSEL.bit.INTEN = 1; // Enable INT
    EPwm1Regs.ETPS.bit.INTPRD = 1; // Generate INT on 1st event
    EALLOW;
    SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1; // Start all the timers synced
    EDIS;
    }

    // Interrupt routines uses in this example
    interrupt void epwm1_timer_isr(void)
    {
    // Clear INT flag for this timer
    EPwm1Regs.ETCLR.bit.INT = 1;
    // Acknowledge this interrupt to receive more interrupts from group 3
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
    }
    void init_Gpio(void)
    {
    EALLOW;
    GpioCtrlRegs.GPAMUX1.bit.GPIO7 = 0; // GPIO7 ABUSY
    GpioCtrlRegs.GPADIR.bit.GPIO7 = 0; // GPIO7 = input
    GpioCtrlRegs.GPAMUX2.bit.GPIO20 = 0; // GPIO20
    GpioCtrlRegs.GPADIR.bit.GPIO20 = 1; // GPIO20 = output
    EDIS;
    }
    void init_zone7(void)
    {
    // Make sure the XINTF clock is enabled
    SysCtrlRegs.PCLKCR3.bit.XINTFENCLK = 1;
    // Configure the GPIO for XINTF with a 16-bit data bus
    // This function is in DSP2833x_Xintf.c
    InitXintf16Gpio();
    EALLOW;
    // All Zones---------------------------------
    // Timing for all zones based on XTIMCLK = SYSCLKOUT
    XintfRegs.XINTCNF2.bit.XTIMCLK = 0;
    // Buffer up to 3 writes
    XintfRegs.XINTCNF2.bit.WRBUFF = 3;
    // XCLKOUT is enabled
    XintfRegs.XINTCNF2.bit.CLKOFF = 0;
    // XCLKOUT = XTIMCLK
    XintfRegs.XINTCNF2.bit.CLKMODE = 0;
    // Disable XHOLD to prevent XINTF bus from going into high impedance state
    // whenever TZ3 signal goes low. This occurs because TZ3 on GPIO14 is
    // shared with HOLD of XINTF
    XintfRegs.XINTCNF2.bit.HOLD = 1;
    // Zone 7------------------------------------
    // When using ready, ACTIVE must be 1 or greater
    // Lead must always be 1 or greater
    // Zone write timing
    XintfRegs.XTIMING7.bit.XWRLEAD = 1;
    XintfRegs.XTIMING7.bit.XWRACTIVE = 2;
    XintfRegs.XTIMING7.bit.XWRTRAIL = 1;
    // Zone read timing
    XintfRegs.XTIMING7.bit.XRDLEAD = 1;
    XintfRegs.XTIMING7.bit.XRDACTIVE = 3;
    XintfRegs.XTIMING7.bit.XRDTRAIL = 0;
    // don't double all Zone read/write lead/active/trail timing
    XintfRegs.XTIMING7.bit.X2TIMING = 0;
    // Zone will not sample XREADY signal
    XintfRegs.XTIMING7.bit.USEREADY = 0;
    XintfRegs.XTIMING7.bit.READYMODE = 0;
    // 1,1 = x16 data bus
    // 0,1 = x32 data bus
    // other values are reserved
    XintfRegs.XTIMING7.bit.XSIZE = 3;
    EDIS;

    __asm(" RPT #7 || NOP");
    }

回帖（2）

张红

2025-1-8 15:55:09
 配置ADS7865内部DAC参考电压，是不是读写都用到了呢。是的话，读写都可以，时序就应该正确啊。电压值是从寄存器里读出来的吗。读别的寄存器看看是否正常。看看数据是否为原始数据。若原始数据不对。要么是读写操作有问题，要么是发送的指令到接收数据的过程不对。逐一排查一下。分析时序最好看示波器
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jjll652

2025-1-9 18:02:55
根据您的描述，您在使用ADS7865与DSP28335进行双通道信号采集时遇到了采集数据为随机数的问题。以下是一些可能的原因和解决方案：

1. 时序问题：确保您的程序时序正确。检查您的代码，确保在读取数据之前，ADS7865已经完成转换。您可以通过在代码中添加延时来解决这个问题。

2. 连接问题：检查您的硬件连接是否正确。确保所有管脚都已正确连接，并且没有短路或断路。特别是CONVST#管脚，您提到它连接到了DSP28335的152管脚，这可能会导致问题。尝试将CONVST#管脚连接到其他可用的GPIO管脚，并在程序中相应地修改。

3. 电源问题：检查您的电源是否稳定。不稳定的电源可能会导致采集数据为随机数。确保您的电源供应器能够提供足够的电流和电压。

4. 晶振问题：您提到使用了32M外部有源晶振。请确保晶振工作正常，频率稳定。您可以使用示波器检查晶振的输出波形。

5. 代码问题：检查您的代码，确保没有逻辑错误。特别是对ADS7865的读写操作，确保您正确地设置了控制寄存器和数据寄存器。

6. 干扰问题：检查您的电路是否存在电磁干扰。电磁干扰可能会导致采集数据为随机数。您可以尝试使用屏蔽电缆和接地来减少干扰。

7. 软件问题：确保您使用的CCS软件和DSP28335的驱动程序是最新的。软件问题可能会导致采集数据为随机数。

综上所述，您需要逐步排查以上可能的原因，找到问题所在，并进行相应的修复。希望这些建议能帮助您解决问题。
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模数转换器 DSP28335 信号采集
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