刚游泳回来，看到昨晚那篇博客访问量比较高，对我是莫大的鼓励，所以马不停蹄的去找了相关的手册准备我们今天的课程。
今天我们要说的是用定时器0产生的定时中断让LED闪烁。
大家都是大部分都是工科出身，应该都学过单片机，单片机也有定时器，跟我们DSP原理都是类似的，但有一点不同：单片机的定时器是加计数器，也就是装载一个预值后，在这个值的基础上进行递加，直到溢出产生中断；我们这款DSP芯片是减计数器，装载预值后，在时钟的基础上进行递减，直到减到0的下一个时钟产生中断。
类似毕竟类似，不是完全一样，我们现在来具体看下F28027的定时器。
我们在中断那节课的时候，96个中断是如何分布的，现在我们回顾下三个定时器
void InitCpuTimers(void)
{
// CPU Timer 0
// Initialize address pointers to respective timer registers:
CpuTimer0.RegsAddr = &CpuTimer0Regs;
// Initialize timer period to maximum:
CpuTimer0Regs.PRD.all = 999;
// Initialize pre-scale counter to divide by 1 (SYSCLKOUT):
CpuTimer0Regs.TPR.bit.TDDR = 59;
CpuTimer0Regs.TPRH.bit.TDDRH = 0;
// Make sure timer is stopped:
CpuTimer0Regs.TCR.bit.TSS = 1;
// Reload all counter register with period value:
CpuTimer0Regs.TCR.bit.TRB = 1;
// Reset interrupt counters:
CpuTimer0.InterruptCount = 0;
// CpuTimer 1 and CpuTimer2 are reserved for DSP BIOS & other RTOS
// Do not use these two timers if you ever plan on integrating
// DSP-BIOS or another realtime OS.
//
// Initialize address pointers to respective timer registers:
CpuTimer1.RegsAddr = &CpuTimer1Regs;
CpuTimer2.RegsAddr = &CpuTimer2Regs;
// Initialize timer period to maximum:
CpuTimer1Regs.PRD.all = 0xFFFFFFFF;
CpuTimer2Regs.PRD.all = 0xFFFFFFFF;
// Initialize pre-scale counter to divide by 1 (SYSCLKOUT):
CpuTimer1Regs.TPR.all = 0;
CpuTimer1Regs.TPRH.all = 0;
CpuTimer2Regs.TPR.all = 0;
CpuTimer2Regs.TPRH.all = 0;
// Make sure timers are stopped:
CpuTimer1Regs.TCR.bit.TSS = 1;
CpuTimer2Regs.TCR.bit.TSS = 1;
// Reload all counter register with period value:
CpuTimer1Regs.TCR.bit.TRB = 1;
CpuTimer2Regs.TCR.bit.TRB = 1;
// Reset interrupt counters:
CpuTimer1.InterruptCount = 0;
CpuTimer2.InterruptCount = 0;
}定时器初始化函数如上所示，现在开始写中断了，回顾下，大家还记得定时中断0 TINT0在哪个PIE中断组吗
interrupt void TINT0_ISR(void) // CPU-Timer 0
{
// Insert ISR Code here
GpioDataRegs.GPATOGGLE.all=0x000000ff;
// To receive more interrupts from this PIE group, acknowledge this interrupt
PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
// Next two lines for debug only to halt the processor here
// Remove after inserting ISR Code
//asm (" ESTOP0");
//for(;;);
}编写主函数：
void main(void)
{
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2802x_SysCtrl.c file.
InitSysCtrl();
// Step 2. Initalize GPIO:
// This example function is found in the DSP2802x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
InitGpio();
// 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 DSP2802x_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 DSP2802x_DefaultIsr.c.
// This function is found in DSP2802x_PieVect.c.
InitPieVectTable();
// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2802x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
// Step 5. User specific code:
GpioDataRegs.GPADAT.all = 0x00000000; //GPIO0-GPIO31 initial value are 0
CpuTimer0Regs.TCR.bit.TIE = 1;
StartCpuTimer0();
EALLOW;
PieCtrlRegs.PIEIER1.bit.INTx7 = 1;
PieCtrlRegs.PIECTRL.bit.ENPIE = 1;
IER = 0x0001;
EINT;
EDIS;
while(1)
{
// GpioDataRegs.GPATOGGLE.all=0x000000ff;
// DELAY_US(1000);
}
}OK，写完了，导入Proteus测试下。测试结果OK，达到预期效果。
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