DSP_CPU_Example_2833x_CpuTimer

  

 

 

• 中斷副程式的宣告

__interrupt void cpu_timer0_isr(void);

進入副程式

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

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

 

　其目的是把  InterruptCount ++

接下來  PIEACK.all = 1來把ACK信號清除(如下圖)

 

 (一定要清除，不然若有其他週邊中斷就無法使用這個cpu中斷)

•  系統初始化

InitSysCtrl();

 

進入該程式

InitSysCtrl();

void 
InitSysCtrl(void)
{

    DisableDog();        //Disable看門狗計數器
    InitPll(DSP28_PLLCR,DSP28_DIVSEL);     //初始SYSCLKOUT??幹!!還看不懂
    InitPeripheralClocks();
}

 

進入InitPll(DSP28_PLLCR,DSP28_DIVSEL);   已得知DSP28_PLLCR=10；DSP28_DIVSEL=2
只看相關聯的部分

void 
InitPll(Uint16 val, Uint16 divsel)        //val=10; divsel=2
{
    //
    // Change the PLLCR
    //
    if (SysCtrlRegs.PLLCR.bit.DIV != val)
    {
        EALLOW;
        
        //
        // Before setting PLLCR turn off missing clock detect logic   在設置PLLCR之前，關閉先漏掉時鐘檢測邏輯
        //
        SysCtrlRegs.PLLSTS.bit.MCLKOFF = 1;
        SysCtrlRegs.PLLCR.bit.DIV = val;
        EDIS;
　　　　

        DisableDog();

        while(SysCtrlRegs.PLLSTS.bit.PLLLOCKS != 1)
        {
            //
            // Uncomment to service the watchdog
            //
            //ServiceDog();
        }

        EALLOW;
        SysCtrlRegs.PLLSTS.bit.MCLKOFF = 0;
        EDIS;
    }

    //
    // If switching to 1/2
    //
    if((divsel == 1)||(divsel == 2))
    {
        EALLOW;
        SysCtrlRegs.PLLSTS.bit.DIVSEL = divsel;
        EDIS;
    }

    //
    // NOTE: ONLY USE THIS SETTING IF PLL IS BYPASSED (I.E. PLLCR = 0) OR OFF
    // If switching to 1/1
    // * First go to 1/2 and let the power settle
    //   The time required will depend on the system, this is only an example
    // * Then switch to 1/1
    //
}

 

 

 

 

• Disable CPU interrupts

 DINT;  //中斷Disable

 

 

 

• 初始PIE的控制

 InitPieCtrl();

 

進入該程式

void 
InitPieCtrl(void)
{
    //
    // Disable Interrupts at the CPU level    DINT;


    // Disable the PIE    PieCtrlRegs.PIECTRL.bit.ENPIE = 0;

    // Clear all PIEIER registers    PieCtrlRegs.PIEIER1.all = 0;
    PieCtrlRegs.PIEIER2.all = 0;
    PieCtrlRegs.PIEIER3.all = 0;    
    PieCtrlRegs.PIEIER4.all = 0;
    PieCtrlRegs.PIEIER5.all = 0;
    PieCtrlRegs.PIEIER6.all = 0;
    PieCtrlRegs.PIEIER7.all = 0;
    PieCtrlRegs.PIEIER8.all = 0;
    PieCtrlRegs.PIEIER9.all = 0;
    PieCtrlRegs.PIEIER10.all = 0;
    PieCtrlRegs.PIEIER11.all = 0;
    PieCtrlRegs.PIEIER12.all = 0;

    // Clear all PIEIFR registers

    PieCtrlRegs.PIEIFR1.all = 0;
    PieCtrlRegs.PIEIFR2.all = 0;
    PieCtrlRegs.PIEIFR3.all = 0;    
    PieCtrlRegs.PIEIFR4.all = 0;
    PieCtrlRegs.PIEIFR5.all = 0;
    PieCtrlRegs.PIEIFR6.all = 0;
    PieCtrlRegs.PIEIFR7.all = 0;
    PieCtrlRegs.PIEIFR8.all = 0;
    PieCtrlRegs.PIEIFR9.all = 0;
    PieCtrlRegs.PIEIFR10.all = 0;
    PieCtrlRegs.PIEIFR11.all = 0;
    PieCtrlRegs.PIEIFR12.all = 0;
}    

 

 把所有的PIEIER跟PIEIFR的旗標寫成0 (如下圖參考)

 

 

 

 

 

 

•  Disable CPU interrupts and clear all CPU interrupt flags:

   IER = 0x0000;
   IFR = 0x0000;

 

 

 

•  初始化PIE向量表

 InitPieVectTable();

 

 

• 將中斷服務程式對應到PIE中斷向量表來啟動相對應的服務

   EALLOW;  // 解除暫存器保護(有的暫存器要解開保護才能寫入)
   PieVectTable.TINT0 = &cpu_timer0_isr;
   EDIS;    // 讓暫存器進入保護

 

 

• 初始CPU Timers

InitCpuTimers();

 

進入

void 
InitCpuTimers(void)
{
    //
    // CPU Timer 0 - 初始化地址指針到各自的定時器寄存器
    //
    CpuTimer0.RegsAddr = &CpuTimer0Regs;          //mapping到Register   &為取址(指向那裡用&)
    

//CouTimer0已經定義好需要哪些東西

struct CPUTIMER_VARS {
    //RegsAddr是一個幫忙Register的東西，所以必須把他只向一個位置，告訴她須從哪裡撈出這些Data，所以指向了extern volatile struct CPUTIMER_REGS CpuTimer0Regs;
　　volatile struct  CPUTIMER_REGS  *RegsAddr;  

    Uint32    InterruptCount;
    float   CPUFreqInMHz;
    float   PeriodInUSec;
};

//
    // Initialize timer period to maximum(設為最大值)
    //
    CpuTimer0Regs.PRD.all  = 0xFFFFFFFF;
    
    //
    // Initialize pre-scale counter to divide by 1 (SYSCLKOUT)
    //
    CpuTimer0Regs.TPR.all  = 0;
    CpuTimer0Regs.TPRH.all = 0;
    
    //
    // 初始時，把計時器先停止  TSS=1  為停止
    //
    CpuTimer0Regs.TCR.bit.TSS = 1;
    
    //
    // 初始時，要重載計時器暫存器的暫存值
    //
    CpuTimer0Regs.TCR.bit.TRB = 1;
    
    //
    // 重置中斷計數器
    //
    CpuTimer0.InterruptCount = 0;

 

 

 

• 設定CPU時間

 

ConfigCpuTimer(&CpuTimer0, 150, 1000000);      //150=>SYSCLKOUT    100000=M=10^6

 

進入

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

    //
    // Initialize timer period
    //
    Timer->CPUFreqInMHz = Freq;
    Timer->PeriodInUSec = Period;
    temp = (long) (Freq * Period);
    Timer->RegsAddr->PRD.all = temp;    //timer period to 150MHZ  =>  設為150*10^6

    //
    // Set pre-scale counter to divide by 1 (SYSCLKOUT)  (設為一秒鐘    (為什麼是1S???還要再確認一下))
    //
    Timer->RegsAddr->TPR.all  = 0;　　　　　　　　//除頻因子  
    Timer->RegsAddr->TPRH.all  = 0;　　　　　　　 //除頻因子　(TPRH:TPR+1=>0+1=1  故SYSCLKOUT/1=原本)

    //
    // Initialize timer control register
    //
    
    //
    // 1 = Stop timer, 0 = Start/Restart Timer
    //
    Timer->RegsAddr->TCR.bit.TSS = 1;     //TSS=1  Disable
    
    Timer->RegsAddr->TCR.bit.TRB = 1;    // 1 = reload timer  重新仔入
    Timer->RegsAddr->TCR.bit.SOFT = 1;
    Timer->RegsAddr->TCR.bit.FREE = 1;   // Timer Free Run   
    
    //
    // 0 = Disable/ 1 = Enable Timer Interrupt   計時器中斷Enable
    //
    Timer->RegsAddr->TCR.bit.TIE = 1;    

    //
    // Reset interrupt counter    (清除觀測變數)
    //
    Timer->InterruptCount = 0;
}

 

• 把TSS設為0來啟動Timer

CpuTimer0Regs.TCR.all = 0x4000;

 

(所以前面要先TSS設為1讓Timer先不跑，再把暫存器設定完成，最後再把TSS開啟)

 

• Enable CPU Timer 0

 IER |= M_INT1;

 

 

• 啟動PIE的INT1.7

PieCtrlRegs.PIEIER1.bit.INTx7 = 1;

 

可對照下圖得知把中斷向量

可看出INT1.7為 Timer 0 故要啟動它

 

•  最後步驟

// Enable global Interrupts and higher priority real-time debug events:
   EINT;   // Enable Global interrupt INTM=0
   ERTM;   // Enable Global realtime interrupt DBGM(啟動中斷在即時粉真模式下(CPU暫停)  ??靠北  也看不懂)

// Step 6. IDLE loop. Just sit and loop forever (optional):
   for(;;);

 

 

 

• 最後附上全部程式碼    (PS:有偷偷把Timer1&2先砍掉)

 

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

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

void main(void)
{
// 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 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 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();

// 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 DSP2833x_CpuTimers.c
   InitCpuTimers();   // For this example, only initialize the Cpu Timers

#if (CPU_FRQ_150MHZ)
// Configure CPU-Timer 0, 1, and 2 to interrupt every second:
// 150MHz CPU Freq, 1 second Period (in uSeconds)

   ConfigCpuTimer(&CpuTimer0, 150, 1000000);
#endif

// 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 DSP2833x_CpuTimers.h), the
// below settings must also be updated.

   CpuTimer0Regs.TCR.all = 0x4000; // Use write-only instruction to set TSS bit = 0


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

// Enable CPU int1 which is connected to CPU-Timer 0, CPU int13
// which is connected to CPU-Timer 1, and CPU int 14, which is connected
// to CPU-Timer 2:
   IER |= M_INT1;
   IER |= M_INT13;
   IER |= M_INT14;

// 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(;;);
}

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

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

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// No more.
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