DSP28335的上手试用LED灯闪烁-第一篇

1. 本次以三兄弟的DSP28335开发板为例，看下JTAG接口，EMU0，EMU1的用途，不是很懂，不深入研究，用到再说

EMU0/1是TI芯片的JTAG才有的信号，本身不属于JTAG标准里的信号，有两个作用。

（1）设定芯片是仿真模式（上拉）还是边界扫描模式（下拉）。

（2）用做高速实时数据交换RTDX及TRACE等功能时。这个一般用户可能用不到。

所以这两个信号是双向的，这个信号一般来说不需加要buffer，直接连起来就好了，不用管他是单向还是双向。

2. 打开工程，E:\dsp\SXD_C28335\SXD28335_PRO_1_V2\Example_2833x_LEDBlink，建立一个CCXML文件，编译一下工程

3. 看下引脚原理图，28335有3组GPIO，每组GPIO最多有32个引脚，但是28335是16位的，所以每组GPIO有高低寄存器

4. GPIO寄存器

5. 代码研究一下，看了一下底层用的是C2000WARE里面的库函数。

 #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. Initalize 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 to interrupt every 500 milliseconds:
 // 150MHz CPU Freq, 50 millisecond Period (in uSeconds)
    ConfigCpuTimer(&CpuTimer0, , );
 #endif
 #if (CPU_FRQ_100MHZ)
 // Configure CPU-Timer 0 to interrupt every 500 milliseconds:
 // 100MHz CPU Freq, 50 millisecond Period (in uSeconds)
    ConfigCpuTimer(&CpuTimer0, , );
 #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 = 0x4001; // Use write-only instruction to set TSS bit = 0

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

 // Configure GPIO32 as a GPIO output pin
    EALLOW;
    GpioCtrlRegs.GPBMUX2.bit.GPIO53 = ;
    GpioCtrlRegs.GPBDIR.bit.GPIO53 = ;
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = ;
    GpioCtrlRegs.GPADIR.bit.GPIO0 = ;
    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 = ;

 // 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++;
    GpioDataRegs.GPBTOGGLE.all = 0x40000004; // Toggle GPIO32 once per 500 milliseconds
    GpioDataRegs.GPBTOGGLE.bit.GPIO53 = ;
    GpioDataRegs.GPATOGGLE.bit.GPIO0 = ;
    // Acknowledge this interrupt to receive more interrupts from group 1
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
 }

6. 看下GPIO的全局变量volatile struct GPIO_CTRL_REGS GpioCtrlRegs;，volatile 确保本条指令不会被编译器优化，从下面看的出来，函数库将GPIOA，GPIOB，GPIOC，的控制寄存器全部写在一起了。数据寄存器也是一样的GpioDataRegs.GPATOGGLE.bit.GPIO0 = 1;

 struct GPIO_CTRL_REGS {
    union  GPACTRL_REG  GPACTRL;   // GPIO A Control Register (GPIO0 to 31)
    union  GPA1_REG     GPAQSEL1;  // GPIO A Qualifier Select 1 Register (GPIO0 to 15)
    union  GPA2_REG     GPAQSEL2;  // GPIO A Qualifier Select 2 Register (GPIO16 to 31)
    union  GPA1_REG     GPAMUX1;   // GPIO A Mux 1 Register (GPIO0 to 15)
    union  GPA2_REG     GPAMUX2;   // GPIO A Mux 2 Register (GPIO16 to 31)
    union  GPADAT_REG   GPADIR;    // GPIO A Direction Register (GPIO0 to 31)
    union  GPADAT_REG   GPAPUD;    // GPIO A Pull Up Disable Register (GPIO0 to 31)
    Uint32              rsvd1;
    union  GPBCTRL_REG  GPBCTRL;   // GPIO B Control Register (GPIO32 to 63)
    union  GPB1_REG     GPBQSEL1;  // GPIO B Qualifier Select 1 Register (GPIO32 to 47)
    union  GPB2_REG     GPBQSEL2;  // GPIO B Qualifier Select 2 Register (GPIO48 to 63)
    union  GPB1_REG     GPBMUX1;   // GPIO B Mux 1 Register (GPIO32 to 47)
    union  GPB2_REG     GPBMUX2;   // GPIO B Mux 2 Register (GPIO48 to 63)
    union  GPBDAT_REG   GPBDIR;    // GPIO B Direction Register (GPIO32 to 63)
    union  GPBDAT_REG   GPBPUD;    // GPIO B Pull Up Disable Register (GPIO32 to 63)
    Uint16              rsvd2[];
    union  GPC1_REG     GPCMUX1;   // GPIO C Mux 1 Register (GPIO64 to 79)
    union  GPC2_REG     GPCMUX2;   // GPIO C Mux 2 Register (GPIO80 to 95)
    union  GPCDAT_REG   GPCDIR;    // GPIO C Direction Register (GPIO64 to 95)
    union  GPCDAT_REG   GPCPUD;    // GPIO C Pull Up Disable Register (GPIO64 to 95)
 };

7. 还有一些汇编指令，以后再研究吧

 #define  EINT   asm(" clrc INTM")
 #define  DINT   asm(" setc INTM")
 #define  ERTM   asm(" clrc DBGM")
 #define  DRTM   asm(" setc DBGM")
 #define  EALLOW asm(" EALLOW")
 #define  EDIS   asm(" EDIS")
 #define  ESTOP0 asm(" ESTOP0")