工程搭建参考：https://blog.csdn.net/feisy/article/details/126380289

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F28069有三个32位的CPU定时器：0,1,2。0，1可用，如果程序未使用DIS/BIOS，定时器2也可用。

CPU定时器相关的有5个信号，四个输入信号，一个输出信号

1. Reset信号：复位信号，给定时器复位用的
2. Timer reload:定时器重载信号，控制定时器要不要重新装载周期计算器
3. SYSCLKOUT:系统时钟信号
4. TCR.4=TCR.bit.4.TSS:控制定时器计时开始或者停止
5. TINT:输出信息，周期中断

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CPU定时器涉及的寄存器

1. TDDR :定时器减一的时间长度，两个16位的寄存器表示
2. PRD：设置CPU定时器的周期，两个16位的寄存器表示
3. PSC开始计数时，会将TDDR 装载到这里，用来不断自减减到0,到0会产生TIMCLK信号，让TIM减一
4. TIM：开始计数时，会将PRD 装载到这里，用来不断自减，，会产生一个中断信号，这时会回调定时器中断函数
5. TPR：F28069里跟TDDR功能一样的寄存器？
6. TCR：装载，启用或者停止定时器的寄存器：TCR.bit.TSS = 1（1 = Stop timer, 0 = Start/Restart Timer），TCR.bit.TRB = 1（ 1 = reload timer），TCR.bit.TIE = 1（ 0 = Disable/ 1 = Enable Timer Interrupt）

定时器的寄存器的形式是XH:X这样的形式，后半部分X表示低位，前半部分XH表示高位

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#CPU定时器的工作原理

1. 给CPU周期寄存器赋值
   

2. 开始计数时，CPU会将计数值装在到TIM寄存器
   

3. 每个一个TIMCLK，TIM会不断减一，一直减到0
   

4. 减到0，完成一个定时周期，会产生一个中断
   .

TIMCLK代表是了计数器减一的时间长度，它是通过定时器 的分频寄存器TDDR来设置的

计数时，TIMCLK会被装载到PSC寄存器

PSC里面的数值在每个SYSCLK都会减一，减到0时，会产生一个让TIMCLK减一的信号

一个计算例子
PDR会被装载到PSC,每个SYSCLK都会减一，减到0时，会产生一个让TIMCLK减一的信号,TIMCLK=(1+PDR)个SYSCLKOUT,以F28335为例，主频是150M,TIMCLK=(1+PDR)*(1/150M)秒

一个周期是 (1+PRD) * TIMCLK

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代码演示，通过定时器来控制LED闪烁

1 设置定时器的回调函数

注意，TINT0是在PIE TABLE的第7位，后面还有关于启用第一组，以及启用第7个中断的设置

// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
   EALLOW;  // This is needed to write to EALLOW protected registers
   PieVectTable.TINT0 = &cpu_timer0_isr;

   EDIS;    // This is needed to disable write to EALLOW protected registers

2 获取定时器寄存器， 配置定时器的一些默认值

使用到的一个函数

void InitCpuTimers(void)
{
    // CPU Timer 0
	// Initialize address pointers to respective timer registers:
	CpuTimer0.RegsAddr = &CpuTimer0Regs;
	// Initialize timer period to maximum:
	CpuTimer0Regs.PRD.all  = 0xFFFFFFFF;//PRD寄存器设置CPU定时器的周期，两个16位的寄存器表示，这里设置到最大
	//TPR寄存器的作用是CPU会在(TPR[TDDRH:TDDR]+1)个SYSCLOUT后，将TIM减一,这里置0，表示，每个SYSCLKOUT都会让TIM减一
	// Initialize pre-scale counter to divide by 1 (SYSCLKOUT):
	//The 32-bit counter register TIMH:TIM is loaded with
	//the value in the period register PRDH:PRD. The counter decrements once every (TPR[TDDRH:TDDR]+1)SYSCLKOUT cycles, where TDDRH:TDDR is the timer divider. 

	CpuTimer0Regs.TPR.all  = 0;
	CpuTimer0Regs.TPRH.all = 0;
	// Make sure timer is stopped:
	CpuTimer0Regs.TCR.bit.TSS = 1;//TSS=0表示定时器停止
	// Reload all counter register with period value:
	CpuTimer0Regs.TCR.bit.TRB = 1;
	// Reset interrupt counters:
	//CpuTimer0.InterruptCount = 0;


// 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;

}

3 设置定时器的长度

因为F28069的主频是80M，所以我们设置定时器的周期步数是80，每一步是1000000，即1000000个SYSCLKOUT，定时器减一。

// Configure CPU-Timer 0, 1, and 2 to interrupt every second:
// 80MHz CPU Freq, 1 second Period (in uSeconds)

   ConfigCpuTimer(&CpuTimer0, 80, 1000000);

void ConfigCpuTimer(struct CPUTIMER_VARS *Timer, float Freq, float Period)
{
	Uint32 	PeriodInClocks;

	// Initialize timer period:
	Timer->CPUFreqInMHz = Freq;
	Timer->PeriodInUSec = Period;
	PeriodInClocks = (long) (Freq * Period);
	//设置CPU定时器的周期，
	Timer->RegsAddr->PRD.all = PeriodInClocks - 1; // Counter decrements PRD+1 times each period

	//这里这样的设置是每个SYSCLKOUT，都会产生一个TIMCLK，让其减一
	// Set pre-scale counter to divide by 1 (SYSCLKOUT):
	Timer->RegsAddr->TPR.all  = 0;
	Timer->RegsAddr->TPRH.all  = 0;

	// Initialize timer control register:
	Timer->RegsAddr->TCR.bit.TSS = 1;      // 1 = Stop timer, 0 = Start/Restart Timer
	Timer->RegsAddr->TCR.bit.TRB = 1;      // 1 = reload timer
	Timer->RegsAddr->TCR.bit.SOFT = 0;
	Timer->RegsAddr->TCR.bit.FREE = 0;     // Timer Free Run Disabled
	Timer->RegsAddr->TCR.bit.TIE = 1;      // 0 = Disable/ 1 = Enable Timer Interrupt

	// Reset interrupt counter:
	Timer->InterruptCount = 0;

}

4 启用定时器

	//TCR.bit.TSS = 0表示启动寄存器
   CpuTimer0Regs.TCR.all = 0x4000; // Use write-only instruction to set TSS bit = 0

5 启用 中断向量表的第一组

    //
    // Enable CPU INT1 which is connected to CPU-Timer 0
    //
    IER |= M_INT1;

6 启用 中断向量表的第一组的第7个中断

    //
    // Enable TINT0 in the PIE: Group 1 interrupt 7
    //
    PieCtrlRegs.PIEIER1.bit.INTx7 = 1;

7 打开全局中断

// Enable global Interrupts and higher priority real-time debug events:
   EINT;   // Enable Global interrupt INTM
   ERTM;   // Enable Global realtime interrupt DBGM

5 完整代码

//###########################################################################
//
// FILE:   Example_2806xLEDBlink.c
//
// TITLE:  Timer based blinking LED Example
//
//!  \addtogroup f2806x_example_list
//!  <h1>Timer based blinking LED(timed_led_blink)</h1>
//!
//!  This example configures CPU Timer0 for a 500 msec period, and toggles the
//!  GPIO34 LED once per interrupt. For testing purposes, this example
//!  also increments a counter each time the timer asserts an interrupt.
//!
//!  \b Watch \b Variables \n
//!  - CpuTimer0.InterruptCount
//!
//! \b External \b Connections \n
//!  Monitor the GPIO34 LED blink on (for 500 msec) and off (for 500 msec) on
//!  the 2806x control card.
//
//###########################################################################
// $TI Release:  $
// $Release Date:  $
// $Copyright:
// Copyright (C) 2009-2022 Texas Instruments Incorporated - http://www.ti.com/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//   Redistributions of source code must retain the above copyright
//   notice, this list of conditions and the following disclaimer.
//
//   Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the
//   distribution.
//
//   Neither the name of Texas Instruments Incorporated nor the names of
//   its contributors may be used to endorse or promote products derived
//   from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// $
//###########################################################################

//
// Included Files
//
#include "DSP28x_Project.h"     // Device Headerfile and Examples Include File

//
// Function Prototypes statements for functions found within this file.
//
__interrupt void cpu_timer0_isr(void);

//
// Main
//
void main(void)
{
    //
    // Step 1. Initialize System Control:
    // PLL, WatchDog, enable Peripheral Clocks
    // This example function is found in the F2806x_SysCtrl.c file.
    //
    InitSysCtrl();

    //
    // Step 2. Initalize GPIO:
    // This example function is found in the F2806x_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 the 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 F2806x_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 F2806x_DefaultIsr.c.
    // This function is found in F2806x_PieVect.c.
    //
    InitPieVectTable();

    //
    // Interrupts that are used in this example are re-mapped to
    // ISR functions found within this file.
    //
    EALLOW;    // This is needed to write to EALLOW protected registers
    PieVectTable.TINT0 = &cpu_timer0_isr;
    EDIS;      // This is needed to disable write to EALLOW protected registers

    //
    // Step 4. Initialize the Device Peripheral. This function can be
    //         found in F2806x_CpuTimers.c
    //
    InitCpuTimers();   // For this example, only initialize the Cpu Timers

    //
    // Configure CPU-Timer 0 to interrupt every 500 milliseconds:
    // 80MHz CPU Freq, 50 millisecond Period (in uSeconds)
    //
    ConfigCpuTimer(&CpuTimer0, 80, 500000);

    //
    // To ensure precise timing, use write-only instructions to write to the
    // entire register. Therefore, if any of the configuration bits are changed
    // in ConfigCpuTimer and InitCpuTimers (in F2806x_CpuTimers.h), the
    // below settings must also be updated.
    //

    //
    // Use write-only instruction to set TSS bit = 0
    //
    CpuTimer0Regs.TCR.all = 0x4001;

    //
    // Step 5. User specific code, enable interrupts:
    //

    //
    // Configure GPIO34 as a GPIO output pin
    //
    EALLOW;
    GpioCtrlRegs.GPBMUX1.bit.GPIO34 = 0;
    GpioCtrlRegs.GPBDIR.bit.GPIO34 = 1;
    EDIS;

    //
    // Enable CPU INT1 which is connected to CPU-Timer 0
    //
    IER |= M_INT1;

    //
    // Enable TINT0 in the PIE: Group 1 interrupt 7
    //
    PieCtrlRegs.PIEIER1.bit.INTx7 = 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)
    //
    for(;;);
}

//
// cpu_timer0_isr -
//
__interrupt void
cpu_timer0_isr(void)
{
    CpuTimer0.InterruptCount++;

    //
    // Toggle GPIO34 once per 500 milliseconds
    //
    //我之前一直用软件的角度去看代码，以为这个是赋值的意思，但其实这个是硬件中的GPIO的翻转操作
    //，即每次=1,会让GPIO的电平发生变化，变到另外一个状态。
    //比如，原先是高电平，执行一次=1，就变成了低电平了。。。。
    GpioDataRegs.GPBTOGGLE.bit.GPIO34 = 1;

    //
    // Acknowledge this interrupt to receive more interrupts from group 1
    //
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}

//
// End of File
//