LED BLINKING USING DSP BY CPU TIMERS

 

LED BLINKING USING DSP BY CPU TIMERS

To blink LED using Switch by using 4-GPIO Pins that are connected to 4- LED’s at the Peripheral Explorer Board.

SOFTWARE: Code Composer Studio

HARDWARE REQUIRED: DSP controller board (TMS320F28335), JTAG, XDS100V2 board

THEORY:

A Light Emitting Diodes (LEDs) are the most commonly used components, usually for displaying pin’s digital states.

The  TMS320F28335 board has 4- LED Connected with DSP general-purpose I/O pins. The Anode of each LED connects to ground and Cathode of each LED connects port via 220Ω resistor. To light an individual LED, drive the associated port signal to High.

 

The general-purpose input/output (GPIO) peripheral in the TMS320 Digital Signal Processor (DSP). The GPIO peripheral provides dedicated general-purpose pins that can be configured as either inputs or outputs. When configured as an input, we can detect the state of the input by reading the state of an internal register. When configured as an output, we can write to an internal register to control the state driven on the output pin.

Embedded ‘C’ CODE for LED Blinking:

#include "DSP2833x_Device.h"

// Prototype statements for functions found within this file.
void Gpio_select(void);
void InitSystem(void);
void delay_loop(long);


void main(void)
{
    int counter=0;      // binary counter for digital output

    InitSystem();       // Basic Core Initialization

    DINT;               // Disable all interrupts

    Gpio_select();      // GPIO9,GPIO11,GPIO34 and GPIO49 as output (LEDs @ peripheral explorer)

    while(1)
    {

            switch(counter&3)
            {
            case 0:
                GpioDataRegs.GPASET.bit.GPIO9 = 1;
                GpioDataRegs.GPACLEAR.bit.GPIO11 = 1;
                GpioDataRegs.GPBCLEAR.bit.GPIO34 = 1;
                GpioDataRegs.GPBCLEAR.bit.GPIO49 = 1;
                break;
            case 1:
                GpioDataRegs.GPASET.bit.GPIO11 = 1;
                GpioDataRegs.GPACLEAR.bit.GPIO9 = 1;
                GpioDataRegs.GPBCLEAR.bit.GPIO34 = 1;
                GpioDataRegs.GPBCLEAR.bit.GPIO49 = 1;
                break;
            case 2:
                GpioDataRegs.GPBSET.bit.GPIO34 = 1;
                GpioDataRegs.GPACLEAR.bit.GPIO9 = 1;
                GpioDataRegs.GPACLEAR.bit.GPIO11 = 1;
                GpioDataRegs.GPBCLEAR.bit.GPIO49 = 1;
                break;
            case 3:
                GpioDataRegs.GPBSET.bit.GPIO49 = 1;
                GpioDataRegs.GPACLEAR.bit.GPIO9 = 1;
                GpioDataRegs.GPACLEAR.bit.GPIO11 = 1;
                GpioDataRegs.GPBCLEAR.bit.GPIO34 = 1;
                break;
            }
            counter++;
            delay_loop(10000000);
    }
}

void delay_loop(long end)
{
    long i;
    for (i = 0; i < end; i++)
    {
        asm(" NOP");
        EALLOW;
        SysCtrlRegs.WDKEY = 0x55;
        SysCtrlRegs.WDKEY = 0xAA;
        EDIS;
    }
}

void Gpio_select(void)
{
    EALLOW;
    GpioCtrlRegs.GPAMUX1.all = 0;       // GPIO15 ... GPIO00 = General Puropse I/O
    GpioCtrlRegs.GPAMUX2.all = 0;       // GPIO31 ... GPIO16 = General Purpose I/O
    GpioCtrlRegs.GPBMUX1.all = 0;       // GPIO47 ... GPIO32 = General Purpose I/O
    GpioCtrlRegs.GPBMUX2.all = 0;       // GPIO63 ... GPIO48 = General Purpose I/O
    GpioCtrlRegs.GPCMUX1.all = 0;       // GPIO79 ... GPIO64 = General Purpose I/O
    GpioCtrlRegs.GPCMUX2.all = 0;       // GPIO87 ... GPIO80 = General Purpose I/O

    GpioCtrlRegs.GPADIR.all = 0;
    GpioCtrlRegs.GPADIR.bit.GPIO9 = 1;  // peripheral explorer: LED LD1 at GPIO9
    GpioCtrlRegs.GPADIR.bit.GPIO11 = 1; // peripheral explorer: LED LD2 at GPIO11

    GpioCtrlRegs.GPBDIR.all = 0;        // GPIO63-32 as inputs
    GpioCtrlRegs.GPBDIR.bit.GPIO34 = 1; // peripheral explorer: LED LD3 at GPIO34
    GpioCtrlRegs.GPBDIR.bit.GPIO49 = 1;     // peripheral explorer: LED LD4 at GPIO49
    GpioCtrlRegs.GPCDIR.all = 0;        // GPIO87-64 as inputs
    EDIS;
}

void InitSystem(void)
{
    EALLOW;
    SysCtrlRegs.WDCR = 0x0028;    //0x0028 to Watchdog enabled, 4.3 milliseconds, 0xE8 to disable
    SysCtrlRegs.PLLSTS.bit.DIVSEL = 2;
    SysCtrlRegs.PLLCR.bit.DIV = 10;     // 30MHz * 10 / 2 = 150 MHz
    SysCtrlRegs.HISPCP.all = 0x0001;
    SysCtrlRegs.LOSPCP.all = 0x0002;
    SysCtrlRegs.PCLKCR0.all = 0x0000;
    SysCtrlRegs.PCLKCR1.all = 0x0000;
    SysCtrlRegs.PCLKCR3.all = 0x0000;
    SysCtrlRegs.PCLKCR3.bit.GPIOINENCLK = 1;
    EDIS;
}

 

OBSERVATION:

The LED is blinked in the fashion that the first LED with the minimum blinking, the second one with the more and it keeps the frequency of blink increasing.

 

RESULT:

Hence by the above code, we have blinked the LED with the 4 GPIO Pins.