4 x 7 Segment Display Multiplexing

Please give me code

This is a forum for programmers not for copiers. If you need to cheat to pass your examp, I hope, for the sake of the industry, that you do not pass.

Erik

I am using 89S51 and will use P0 and P1 for display
P0 and P1 can not source/sink enough current to give you a bright Display. So you have to use a driver IC.

Take a look to MAX7219 on http://www.maxim-ic.com

Here is my example-Programm

//**********************************************************************
//  C-Programm for driving a MAX7219
//  a 8 digit number is printed in a string (sprintf)
//  and then send to the MAX7219
//**********************************************************************
#include<c8051f200.h>
//#include<math.h>
//#include<string.h>
#include<stdio.h>

sbit Data7219 = P1^0;
sbit Load7219 = P1^1;
sbit Clk7219 = P1^2;

const unsigned char Font_B[16]=
{
        0x7e,0x30,0x6d,0x79,0x33,0x5b,0x5f,0x70,
        0x7f,0x7b,0x77,0x1f,0x4e,0x3d,0x4f,0x47
};

void Send7219 (char,char);
void Send7219byte(char);
void MAX7219init();
void Display(unsigned long int);
//**********************************************************************
void main (void)
{
        MAX7219init();
        Display(47110815);//my_weird_number
        while(1){}
}
//**********************************************************************
void MAX7219init()
{
        Data7219 =0;
        Load7219 =0;
        Clk7219 = 0;
        Send7219(0x09,0x00);//Decode Mode
        Send7219(0x0A,0x05);//Brightness
        Send7219(0x0B,0x07);//Scan limit
        Send7219(0x0C,0x01);
        Send7219(0x0F,0x00);
}
//**********************************************************************
void Send7219 (char Digit,char Data)
{
        Send7219byte(Digit);
        Send7219byte(Data);
        Data7219=0;
        Load7219=1;
        Load7219=0;
}
//**********************************************************************
void Send7219byte (char byte)
{
unsigned char I;
        for(I=0;I<8;I++)
        {
        if (byte & 0x80)
                Data7219=1;
        else
                Data7219=0;

        Clk7219=1;
        byte<<=1;
        Clk7219=0;
        }
}
//**********************************************************************
void Display (unsigned long int My_number)
{
        unsigned char i,string[8];
        sprintf(string,"%8.lx",My_number);
        for (i=0;i<8;i++)
        {
                if (string[i] == 0x20)//0x20 is ASCII " "
                Send7219(i+1,0);          //send MAX7219 " " to MAX7219
                else    if (string[i] <= 0x39)
                                Send7219(i+1,Font_B[string[i] - 0x30]);//0-9
                                else
                                Send7219(i+1,Font_B[string[i] - 0x57]);//A-F
        }
}
//**********************************************************************

"So you have to use a driver IC."

Well, you don't have to use an IC - you could use discrete transistors...

i will use discrete transistors the day, the hell is frozen ;-)

For my display driver, I use vacuum tubes.

This has the beneficial side effect of making the 8051 seem very modern and advanced by contrast.

... and also warms the room on a chill winter's evening...

For my display driver, I use vacuum tubes.

This has the beneficial side effect ...

Another benefit is that no current is required to drive the grid, just voltage.

Erik

"Another benefit is that no current is required to drive the grid..."

Just as well - cos all the current is being used up in the heater supply!

(6.3VAC, of course...)

(6.3VAC, of course...)

No, I make portable equipment, so I use 6.3V DC

Erik