Question

Using uVison: Write a C program that generates a 1 second square wave on Pin 2 Port B. Using generated signal from that Pin 2, as an input to Pin 3 Port B drive the red LED at the same rate and the Blue LED at half the rate of the Red LED.

Answer 1

I m writing this program for 8051 microcontroller

#include<reg51.h>
void T0M1Delay(void);
sbit mybit=P2^2;
sbit LED=P2^3;

getting input from P2^2
unsignedint i; //data type
void main(void)
{
while(1)
{
mybit=~mybit; //for generation of square wave
RLED=~RLED; //Red led as per the square wave it will be on and off

for(i=0;i<28;i++)
{
T0M1Delay() ; //this is to provide the delay of 1 sec which is required
}
}
BLED=~BLED; //for blue led we want half time
for(i=0;i<14;i++)
{
T0M1Delay() ;//this is to provide half the time delay
}

}
This loop should repeat 28 times to get the delay of 1 sec

void T0M1Delay(void)
{
TMOD=0×01; //timer 0 in mode 1
TL0=0×00; //load the value of TL0
TH0=0×00; //load the value of TH0
TR0=1; //start timer
while(TF0==0); //wait untill TF0 becomes 0
TR0=0;
TF0=0;
}
XTAL frequency=22MHz
so the maximum delay with this crystal frequency is 37.75ms
to get 1 sec delay we take a loop which runs 28 times
=28*35.75
=1000ms=1sec