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:dspSXD_C28335SXD28335_PRO_1_V2Example_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, 150, 500000);
#endif
#if (CPU_FRQ_100MHZ)
// Configure CPU-Timer 0 to interrupt every 500 milliseconds:
// 100MHz CPU Freq, 50 millisecond Period (in uSeconds)
   ConfigCpuTimer(&CpuTimer0, 100, 500000);
#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 = 0;
   GpioCtrlRegs.GPBDIR.bit.GPIO53 = 1;
   GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 0;
   GpioCtrlRegs.GPADIR.bit.GPIO0 = 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(;;);
}

interrupt void cpu_timer0_isr(void)
{
   CpuTimer0.InterruptCount++;
   GpioDataRegs.GPBTOGGLE.all = 0x40000004; // Toggle GPIO32 once per 500 milliseconds
   GpioDataRegs.GPBTOGGLE.bit.GPIO53 = 1;
   GpioDataRegs.GPATOGGLE.bit.GPIO0 = 1;
   // 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[8];
   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")