You Can Achieve What You Believe: August 2016

Lowest square wave frequency that we can generate using mode 1 and mode 2 At XLAT=16MHZ

2KHZ Frequency Wave Generation Programme:

#include<reg51.h>
sbit OUTPUT=P1^7;
void delay()
{
    unsigned int i;
    TMOD=TMOD & 0xF0;
    TMOD=TMOD | 0x01;
    TH0=0xFD;
    TL0=0x66;
    TR0=1;
    while(TF0==0);
    TR1=0;
}
void main()
{
    while(1)
    {
        OUTPUT=1;
        delay();
        OUTPUT=0;
    }
}

Lowest Frequency Generation Explanation:

Lowest Square Wave Frequency Means Highest Time Delay.

Here Our Crystal Or Oscillator Frequency Is 20KHZ.
So Our CP=12/16KHZ=0.75 micro
To Get Maximum Time Delay We Must Have Value Of THX-TLX is 0(zero).

For Mode 1:
    Mode 1 is 16bit-Timer.
    When We Take Initial Value as a 2^16 Than THX-TLX become 0(zero).
    so Initial Value= 2 ^ 16 = 65536
    And We Know CP=0.6 micro
    So TIME= CP * Initial Value
           = 0.75 * 10^-6 * 65536
           = 49152 microsecond
    Now Frequency=1/TIME
                 =1/(49152 * 10^-6)
                 =20.3450 HZ

For Mode 2:
    Mode 1 is 8bit-Timer.
    When We Take Initial Value as a 2^16 Than THX-TLX become 0(zero).
    so Initial Value= 2 ^ 8 = 256
    And We Know CP=0.6 micro
    So TIME= CP * Initial Value
           = 0.75 * 10^-6 * 256
           = 192 microsecond
    Now Frequency=1/TIME
                 =1/(192 * 10^-6)
                 =5.2083 KHZ

Program Timer 0 to generate a square wave of 0.5KHz

XLAT = 20MHz

#include<reg51.h>
sbit OUTPUT=P1^7;
void delay()
{
    unsigned int i;
    TMOD=TMOD & 0xF0;
    TMOD=TMOD | 0x01;
    TH0=0xF2;
    TL0=0xFB;
    TR0=1;
    while(TF0==0);
    TR1=0;
}
void main()
{
    while(1)
    {
        OUTPUT=1;
        delay();
        OUTPUT=0;
    }
}

8051 C program to generate wave of 60 % duty cycle(XLAT=12MHz)

#include<reg51.h>
sbit OUTPUT=P1^7;
void delay(unsigned in T)
{
    unsigned int i;
    TMOD=TMOD & 0x0F;
    TMOD=TMOD | 0x10;
    for(i=0;i<T;i++)
    {
        TMOD=TMOD & 0xF0;
        TMOD=TMOD | 0x01;
        TR0=1;
        while(TF0==0);
        TR0=0;
    }
}
void main()
{
    while(1)
    {
        OUTPUT=1;
        delay(60);
        OUTPUT=0;
    }
}

Genrate Frequancy In 8051 GPIO Pin Using Switch

A switch is connected to pin P1.2. Write an 8051 C program to monitor SW and create the following frequencies on pin P1.7:
SW = 0 :- 500 Hz
SW = 1 :- 750 Hz
XLAT=14MHz

#include<reg51.h>
sbit S=P1^2;
sbit OUTPUT=P1^7;
void delay_1(unsigned int T)
{
    unsigned int i;
    TMOD=TMOD & 0xF0;
    TMOD=TMOD | 0x01;
    for(i=0;i<T;i++)
    {
        TH0=0xFC;
        TL0=0x18;
        TR0=1;
        while(TF0==0);
        TR0=0;
    }
}
void delay_2(unsigned int T)
{
unsigned int i;
TMOD=TMOD & 0xF0;
    TMOD=TMOD | 0x02;
TH0=255;
for(i=0;i<T;i++)
{
  TR0=1;
  while(TF0==0);
  TR0=0;
}
}
void main()
{
    if(S==0)
    {
        OUTPUT=1;
        delay_1(2);
        OUTPUT=0;
    }
    else
    {
        OUTPUT=1;
        delay_2(1333);
        OUTPUT=0;
    }
}

8051 C program to toggle all bits of P2 continuously every 500 ms.

A. Use Timer 1, mode 1 to create delay.

XLAT = 11.0592 MHz

#include <reg51.h>

#define TOG P2;

void delay(int time)

{

                unsigned int i;

                TMOD=TMOD & 0x0f;

                TMOD=TMOD | 0x10;

                for(i=0;i<time;i++)

                {

                TH1=0xfc;

                TL1=0x66;

                TR1=1;

                while(TF1==0);

                TR0=0;

                }

        }

      void main()

     {

                while(1)

                {

                TOG=0xff;

                delay(500);

                TOG=0x00;

                delay(500);

                }

      }
XLAT = 12 MHz

#include <reg51.h>

#define TOG P2;

void delay(int time)

{

                    unsigned int i;

    TMOD=TMOD & 0x0f;

    TMOD=TMOD | 0x10;

    for(i=0;i<time;i++)

    {

        TH1=0xfc;

        TL1=0x18;

        TR1=1;

        while(TF1==0);

        TR0=0;

    }

}



void main()

{

    while(1)

    {

        TOG=0xff;

        delay(500);

        TOG=0x00;

        delay(500);

    }

}
XLAT = 22 MHz

#include <reg51.h>

#define TOG P2;

void delay(int time)

{

    unsigned int i;

    TMOD=TMOD & 0x0f;

    TMOD=TMOD | 0x10;



                   for(i=0;i<time;i++)

    {

        TH1=0xf8;

        TL1=0xd7;

        TR1=1;

        while(TF1==0);

        TR0=0;

    }

}

void main()

{

    while(1)

    {

        TOG=0xff;

        delay(500);

        TOG=0x00;

        delay(500);

    }

}

B. Use Timer 0 , mode 2 to create delay.

XLAT = 11.0592 MHz

#include <reg51.h>

#define TOG P2;

void delay(int time)

{

    unsigned int i;

    TMOD=TMOD & 0xf0;

    TMOD=TMOD | 0x02;

    TH0=0xA3;

    for(i=0;i<time*10;i++)

    {

        TR0=1;

        while(TF0==0);

        TR0=0;

    }

}

void main()

{

    while(1)

    {

        TOG=0xff;

        delay(500);

        TOG=0x00;

        delay(500);

    }

}
XLAT = 12 MHz

#include <reg51.h>

#define TOG P2;

void delay(int time)

{

    unsigned int i;

    TMOD=TMOD & 0xf0;

    TMOD=TMOD | 0x02;

    TH0=156;

    for(i=0;i<time*10;i++)

    {

        TR0=1;

        while(TF0==0);

        TR0=0;

    }

}

void main()

{

    while(1)

    {

        TOG=0xff;

        delay(500);

        TOG=0x00;

        delay(500);

    }

}
XLAT = 22 MHz

#include <reg51.h>

#define TOG P2;

void delay(int time)

{

    unsigned int i;

    TMOD=TMOD & 0xf0;

    TMOD=TMOD | 0x02;

    TH0=72;

    for(i=0;i<time*10;i++)

    {

        TR0=1;

        while(TF0==0);

        TR0=0;

    }

}

void main()

{

    while(1)

    {

        TOG=0xff;

        delay(500);

        TOG=0x00;

        delay(500);

    }

}