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LCD display flickrign problem. Urgent help required.

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please also tell me how much delay will this routine produce with 12MHz crystal?

Code:
#include <reg51.h>
				   
sbit led=P0^0;

void delay(msec)
{
int i,j;
	for (i=0;i<msec;i++)
		for (j=0; j<1275; j++);

}

void main()
{
led=1;
delay(100);
led=0;
delay(100);

}
 
each iteration is about 9mS so with a delay(100) approx 900 mS...

We have been here before.... j<142 = 1ms... the j loop took 7 cycles... 7 * 143 = 994uS + the i loop take another 7 cycles .. 1001uS
 
With VREF+ being connected directly to Vcc any ripple or noise on the Vcc rail will affect the A/D conversion. VREF+ requires decoupling from Vcc by RC filtering components.
The LED drive transistors should each have a resistor (say 10k) between base and emitter to ensure they turn off completely.
 
With VREF+ being connected directly to Vcc any ripple or noise on the Vcc rail will affect the A/D conversion. VREF+ requires decoupling from Vcc by RC filtering components.
The LED drive transistors should each have a resistor (say 10k) between base and emitter to ensure they turn off completely.

hi alec,
This image shows what the d/s says about Vref decoupling.

E.
 
Thanks, Eric. That discusses decoupling the analogue inputs and Vref/2 pin. Can't see any Vref/2 pin on the schematic. Is it the same as VREF+ ?
 
plz check my this routine... i want to select one output at a time. just like rotation of 4 bit data (1000B). but it is giving random selection; with interrupt signal all bits goes high and then any one bit got selected randomly.... i dont know what acctually the problem is???????
Code:
#define select P3

 sbit v28=select^4;
 sbit v14=select^6;
 sbit v7=select^5;
 sbit off=select^7;


	void switching() interrupt 0
		   {

					if(count==0)
						{
							 off=0;  v7=1; v28=0; v14=0;
							 count++;
						}
					else	
					if(count==1)	
						{ 
							v7=0; v14=1; v28=0; off=0; 
							count++;
						}
					else
					if(count==2)
					    {
							v14=0; v28=1; v7=0;  off=0; 
							 count++;
						}

					else
						{ 
						
							count=v28=v14=v7=0; off=1; 
							
						}



		   		/*  if(v28==0 && v14==0 && v7==0 && off==1)
				  		{ off=0;  v7=1; v28=0; v14=0; }
					
				    else
                        if(v28==0 && v14==0 && v7==1 && off==0)
                              { v7=0; v14=1; v28=0; off=0; }
					
					else
						if(v28==0 && v14==1 && v7==0 && off==0)
						      { v14=0; v28=1; v7=0;  off=0; }
					
					else
					   { v28=v14=v7=0; off=1; }	 */
						
		   
		   }

and here is the immage of my circuit.

View attachment 62237
 
Last edited:
any help about my prevous post please??
during interrupt all the bits of port 3 got high and after interrupt it selects any one of the bit High Randomly.. not according to coad..... :( ... how to solve this problem..???
 
Last edited:
the problem is solved :)

the problem was with the interrupt.. we must force the interrupt to go high in order to disable it.. so it will be able to select the required pin correctly....

i am very thank ful to all who help me.

best regards
Qaisar azeemi
 
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