使用TMS320F2812的捕获单元测量外部输入方波的频率的代码

以下是使用TMS320F2812的捕获单元测量外部输入方波的频率的代码：

#include "DSP2812_Device.h"      // DSP2812 Headerfile Include File
#include "DSP2812_Examples.h"    // DSP2812 Examples Include File

#define CPU_FREQ    150E6       // CPU Frequency in Hz
#define PWM_FREQ    10E3        // PWM Frequency in Hz
#define TBCLK_FREQ  CPU_FREQ/2  // TBCLK Frequency in Hz

Uint16 pwmPeriod = (Uint16)(TBCLK_FREQ / PWM_FREQ);

interrupt void cpu_timer0_isr(void);

void main(void)
{
    InitSysCtrl();

    // Configure CPU Timer 0 to interrupt every second
    ConfigCpuTimer(&CpuTimer0, CPU_FREQ, 1000000);

    // Initialize capture unit 1
    InitCpuTimers();

    // Configure GPIO
    EALLOW;
    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 1;   // Disable pull-up on GPIO0
    GpioCtrlRegs.GPAQSEL1.bit.GPIO0 = 0; // Qualify GPIO0 for 3 samples
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;  // Configure GPIO0 as CAP1
    EDIS;

    // Configure capture unit 1
    CpuTimer1Regs.TCR.bit.TSS = 1;       // Stop timer
    CpuTimer1Regs.TCR.bit.TRB = 1;       // Reload timer
    CpuTimer1Regs.TCR.bit.SOFT = 0;
    CpuTimer1Regs.TCR.bit.FREE = 0;
    CpuTimer1Regs.TCR.bit.TIE = 1;       // Enable interrupt
    CpuTimer1Regs.TCR.bit.TSS = 0;       // Start timer

    // Enable interrupts
    EINT;                               // Enable Global interrupt INTM
    ERTM;                               // Enable Global realtime interrupt DBGM

    while(1)
    {
        // Wait for interrupt
    }
}

interrupt void cpu_timer0_isr(void)
{
    // Clear interrupt flag
    CpuTimer0.InterruptCount++;

    // Calculate frequency
    Uint16 capturePeriod = CpuTimer1Regs.CAP1;
    float captureFreq = TBCLK_FREQ / (float)capturePeriod;

    // Reset capture unit 1
    CpuTimer1Regs.TCR.bit.TSS = 1;       // Stop timer
    CpuTimer1Regs.TCR.bit.TRB = 1;       // Reload timer
    CpuTimer1Regs.TCR.bit.TSS = 0;       // Start timer

    // Do something with captureFreq...
}

在这个示例中，我们使用CPU Timer 0定期触发中断。在中断处理程序中，我们读取捕获单元1的值，并计算输入方波的频率。然后，我们重置捕获单元1以准备下一个测量。请注意，我们使用CPU Timer 1作为捕获单元。在初始化函数中，我们将其配置为使用GPIO0作为输入端口，并启用中断。