Problem with 7 segment common Cathode display using C8051F350 Micro Controller

[Nallapaneni Sai Sankar]

 

//

---

#include <c8051f350.h>  

#include<stdio.h>                  // SFR declarations

 

sbit strobe =P1^1;

sbit din =P1^0;

sbit clk =P0^7;/*all chipselects are configured here using sbit;all on P1*/

sbit cs1 =P1^7;

 

sbit cy =PSW^7; //ealrier declared as global

bit temp;

 

unsigned char dd[10] ={~0x3f,~0x06,~0x5b,~0x4f,~0x66,~0x6d,~0x7d,~0x07,~0x7f,~0x6f};

unsigned int value;

 

void delay(void) //creating trouble

{

 

TMOD=0x10;

TL1=0xfb;

TH1=0xff;

TR1=1;

while(TF1==0);

TF1=0;

TR1=0;

 

}

 

void senddata(unsigned char x)

{

unsigned char i;

 

 

 

din = 0;

cy = 0;

strobe = 1;

temp =0;

P2 = x;

  for(i=1; i<=8; i++)

{

cy=0;

x= x << 1; //shifting x places the MSB in carryflag(cy);

temp = cy;

 

din=temp; //data input to the shift register should be sended serially;

clk=1;

clk=0;

}

 

strobe=1;

 

strobe=0;

 

 

}

 

void display(char f1)

{

 

cs1 = 0x01; //before every data send operation data line should be cleared sending 0xff

if(value == 10)

{

senddata(f1);

cs1 &=0x00;

delay();

cs1 |=0x01;

}

else

{

senddata(0xff);

cs1 &=0x00;

delay();

cs1 |=0x01;

if(value == 20)

    value = 0;

}

 

 

}

//

---

// MAIN Routine

//

---

 

void led_display() 

{

 

while(1)

{

value++;

display(dd[~0x3f]);

}

 

}

 

 

 

                                      Thye above is the code that i am using to blink a value in a 7 segment display but what happening is after "2 increments of the 'value' it was getting resetted and the 'value' is becoming zero"  and when i doing on board debugging after 'value' becomes 2 it was automaticalli becoming zero and going into start up code . Help me anyone to solve this .

[AJISH ALFRED]

Hi Nallapaneni,

It is obvious that your delay () function is causing trouble. For this particular project precise delay don’t have that much significance.

Just create a delay using loop waiting technique.

 

For example;

 

void delay_us ( int us )

{

        volatile int uss;

       

        uss = us;

 

        for ( ; uss; uss — );   //assume 1 microsecond for each loop

}

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