c programming of 8051 with 8255a

[logukalipal]

hi.. I am connected ppi 8255a with 8051 on address of 4000h . How can i write the control word for 8255a in c programming?
Thanks in advance.hi.. I am connected ppi 8255a with 8051 on address of 4000h . How can i write the control word for 8255a in c programming?
Thanks in advance.

 

[bassa]

Before write to the control register of 8255, set the A0 = 1 and A1 = 1 then send the data to D0-D7. Sometime this may be 4003H based on your circuit diagram.

 

[logukalipal]

CODE:

xdata[4003]=0x9b;

But keil shows the below error,

syntax error near '['

Tanks in advance..

 

[jayanth.devarayanadurga]

Will 8051 hold such a big array? What type is xdata[], char or int? Post the full code.

 

[logukalipal]

I want to set portA of 8255 is O/P in mode 0.
So i write hex (0x83) to control register( 0x4003) of 8255 ppi ,
how can achieve this?

MY CODING:

//Program to make a digital thermometer with display in centigrade scale

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Code C++ - [expand]
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#include<reg51.h>
#include<absacc.h>
#define port P1
#define sec 100
 
char xdata lcdctr _at_ 0x4001;        //8255 ppi 1 portB for sending control signal to lcd
 
char xdata adc_input _at_ 0x8000;   // adc data connected to portA of 8255 ppi 2
char xdata dataport _at_ 0x4000;     // 8255 ppi 1 portA for sending data to lcd
 
 
unsigned char xdata[0x4003]==0x83;
 
//sbit rs = port^0;
//sbit rw = port^1;
//sbit e = port^2;
 
sbit wr= port^0;
sbit rd= port^1;
sbit intr= port^2;
 
int test_intermediate3=0, test_final=0,test_intermediate1[10],test_intermediate2[3]={0,0,0};
 
void delay(unsigned int msec )
{
int i ,j ;
for(i=0;i<msec;i++)
  for(j=0; j<1275; j++);
}
 
void lcd_cmd(unsigned char item)  //Function to send command to LCD
{
dataport = item;
lcdctr=0x04;
//rs= 0;
//rw=0;
//e=1;
delay(1);
lcdctr=0x00;
//e=0;
 
return;
}
 
void lcd_data(unsigned char item) //Function to send data to LCD
{
dataport = item;
lcdctr=0x05;
//rs= 1;
//rw=0;
//e=1;
delay(1);
lcdctr=0x01;
//e=0;
//delay(100);
return;
}
 
void lcd_data_string(unsigned char *str)  // Function to send string to LCD
{
int i=0;
while(str[i]!='\0')
{
  lcd_data(str[i]);
  i++;
  delay(10);
}
return;
}
 
void shape()     // Function to create the shape of degree
{
lcd_cmd(64);
lcd_data(2);
lcd_data(5);
lcd_data(2);
lcd_data(0);
lcd_data(0);
lcd_data(0);
lcd_data(0);
lcd_data(0);
}
     
void convert()    // Function to convert the values of ADC into numeric value to be sent to LCD
{
int s;
test_final=test_intermediate3;
lcd_cmd(0xc1); 
delay(2);
lcd_data_string("TEMP:");
s=test_final/100;
test_final=test_final%100;
lcd_cmd(0xc8);
if(s!=0)
lcd_data(s+48);
else
lcd_cmd(0x06);
s=test_final/10;
test_final=test_final%10;
lcd_data(s+48);
lcd_data(test_final+48);
lcd_data(0);
lcd_data('c');
lcd_data(' ');
delay(2);
}
 
void main()
{
int i,j;
//adc_input=0xff;   ////////////
lcd_cmd(0x38); 
lcd_cmd(0x0c);  //Display On, Cursor  Blinking
delay(2);
lcd_cmd(0x01);  // Clear Screen
delay(2);
 
while(1)
{
  for(j=0;j<3;j++)
  {
   for(i=0;i<10;i++)
   {
    delay(1);
    rd=1;
    wr=0;
    delay(1);
    wr=1;
    while(intr==1);
    rd=0;
    lcd_cmd(0x88);
    test_intermediate1[i]=adc_input/10;
    delay(1);
    intr=1;
   }
   for(i=0;i<10;i++)
   test_intermediate2[j]=test_intermediate1[i]+test_intermediate2[j];
  }
 
test_intermediate2[0]=test_intermediate2[0]/3;
test_intermediate2[1]=test_intermediate2[1]/3;
test_intermediate2[2]=test_intermediate2[2]/3;
test_intermediate3=test_intermediate2[0]+test_intermediate2[1]+test_intermediate2[2];
shape();
convert();
}
}

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[jayanth.devarayanadurga]

char xdata lcdctr _at_ 0x4001;
char xdata adc_input _at_ 0x8000;
char xdata dataport _at_ 0x4000;


unsigned char xdata[0x4003]==0x83;

The first 3 lines are wrong. If you want to declare a variable at some absolute address you have to use something like this

char xdata _at_ 0x4001;

In your declaration how does the compiler interpret space between xdata and lcdctr?

And in unsigned char xdata[0x4003] == 0x83; which is wrong because 0x4003 = d16387. So it created an array named xdata of 16387 elements and you are assigning only one value to the array and you are using == instead of =. In array initialization you have to initialize all the elements of the array.

You should use something like

char xdata _at_ 0x4001; which will create variable xdata at address 0x4001.

I don't know much about 8051 but in mikroE Compiler we use something like

unsigned char readbuff[64] absolute 0x500;
unsigned char writebuff[64] absolute 0x540;

It created an array of type unsigned char of 64 bytes starting at the addresses mentioned.

This might help you. https://sites.google.com/site/controlandelectronics/interface-lcd-with-8051-using-8255-pia