hi Engineers;

i want set up touch screen lcd but i have some problem.

i can't working with ADC and geting x,y coordinate.

this below is my code of codevision :

thanks for your help.

LCD specifications:
3.2 inch
chip : ssd1289

microcontroller:
AT mega32

#include <mega32a.h>
#include <delay.h>
#include<stdlib.h>

#include "SSD1289.h"


#define ADC_VREF_TYPE 0x00

// Read the AD conversion result
unsigned int read_adc(unsigned char adc_input)
{
ADMUX=adc_input | (ADC_VREF_TYPE & 0xff);
// Delay needed for the stabilization of the ADC input voltage
delay_us(10);
// Start the AD conversion
ADCSRA|=0x40;
// Wait for the AD conversion to complete
while ((ADCSRA & 0x10)==0);
ADCSRA|=0x10;
return ADCW;
}

 int xx,yy;
 char strx[5];
 char stry[5];
void main(void)
{
  char strx[16];
  char stry[16];
 int x,y;
 
int Temp_adcY,Temp_adcX;
// ADC initialization
// ADC Clock frequency: 1000.000 kHz
// ADC Voltage Reference: AREF pin
ADMUX=ADC_VREF_TYPE & 0xff;
ADCSRA=0x83;
lcd_init();
   
  DDRB=0xff;
  DDRC=0xff;
  DDRD=0xff;
   
   
   
  while(1)
  {   
   
   
  lcd_clear();
  lcd_background_color(YELLOW);
   
   
  DDRA= 0xF3;
  PORTA.0= 0;
  PORTA.1=1;
  xx = read_adc(2);
  DDRA= 0xFC;
  PORTA.2= 0;
  PORTA.3=1;
  yy = read_adc(0);
  itoa(yy,stry);
  itoa(xx,strx);
  lcd_gotoxy(0,0);
  lcd_puts(strx,RED,BLACK);
  lcd_gotoxy(10,10);
  lcd_puts(stry,RED,BLACK);
  delay_ms(125);
  lcd_clear();
   
  }
 
   
   
}

 

values on the lcd is stable. not variable
i think my adc cofigurations is incorrect. please checking it. thnaks

 

please give me correct code of adc configurations

 

Your A2D just might be correct (I will not check as this is not a device I am familiar with). However, it seems you are just reading the pin output voltage on your A2D due to improperly driving the touch sensor.

I am assuming this is a resistive sensor from the scant information you give based on the outputs being in the form of X+, X-, Y+, Y-. These are sensed by establishing a voltage across one direction and reading the voltage on the other direction. Why?

Say you put 3.3V on Y+ and 0V on Y-. When you touch the screen you connect the Y side to the X side, so whatever voltage is on Y at that point will be conducted to both X terminals (so you could read either one). But to read the X terminals you need to make them analog inputs as the voltage can be anywhere from 0 to 3.3V (and digital inputs don't work well with in between voltages).

So to read Y:
A0=analog input
A1= high
A3=low
A4=analog input
Read either A0 or A4.

To read X:
A0=high
A1= analog input
A3=analog input
A4=low
Read either A1 or A3.

If you set and forget in either X or Y reading conditions you should be able to take a voltmeter and watch the voltage change as your finger skims across the screen.

 

hi. thanks for help

i have new problems. plz help me!!

this is my code

base on my code and ifs in codes .this should type my text but ..

#include <mega32a.h>
#include <delay.h>
#include <stdlib.h>
#include "SSD1289.h"

#define ADC_VREF_TYPE 0x20
unsigned char read_adc(unsigned char adc_input)
{
ADMUX=adc_input | (ADC_VREF_TYPE & 0xff);
delay_us(10);
ADCSRA|=0x40;
while ((ADCSRA & 0x10)==0);
ADCSRA|=0x10;
return ADCH;
}



int xx,yy;
char strx[15];
char stry[15];

void init();
 
void main(void)
{  
      int x,y;
   char out[20];
 
  
  
   int i,j=5;



ADMUX=ADC_VREF_TYPE & 0xff;
ADCSRA=0x83;


  lcd_init();
   

     /* 
        lcd_gotoxy(5,10);
        lcd_puts("wellcom to my project",GREEN,BLACK);
        delay_ms(50);
        */     
         
       
     
          lcd_clear();
         
           //YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY
             lcd_draw_line(22,238,22,320,BLACK);    
             lcd_draw_line(44,238,44,320,BLACK);
             lcd_draw_line(66,238,66,320,BLACK);
             lcd_draw_line(88,238,88,320,BLACK);
             lcd_draw_line(110,238,110,320,BLACK);
             lcd_draw_line(132,238,132,320,BLACK);
             lcd_draw_line(154,238,154,320,BLACK);
             lcd_draw_line(176,238,176,320,BLACK);
             lcd_draw_line(198,238,198,320,BLACK);
             lcd_draw_line(220,238,220,320,BLACK);
             //-------------------------------------
             //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
             lcd_draw_line(0,238,240,238,BLACK);    
             lcd_draw_line(0,266,240,266,BLACK);
             lcd_draw_line(0,293,240,293,BLACK);
           
             lcd_gotoxy(1,239);
             lcd_putchar('Q',BLACK,WHITE);
              lcd_gotoxy(4,239);
             lcd_putchar('W',BLACK,WHITE);
              lcd_gotoxy(7,239);
             lcd_putchar('E',BLACK,WHITE);
              lcd_gotoxy(9,239);
             lcd_putchar('R',BLACK,WHITE);
              lcd_gotoxy(12,239);
             lcd_putchar('T',BLACK,WHITE);
              lcd_gotoxy(15,239);
             lcd_putchar('Y',BLACK,WHITE);
              lcd_gotoxy(18,239); 
             lcd_putchar('U',BLACK,WHITE);
              lcd_gotoxy(20,239);
             lcd_putchar('I',BLACK,WHITE);
              lcd_gotoxy(23,239);
             lcd_putchar('O',BLACK,WHITE);
              lcd_gotoxy(25,239);
             lcd_putchar('P',BLACK,WHITE);
             lcd_gotoxy(28,239);
             lcd_putchar('(',BLACK,WHITE);  
           
             lcd_gotoxy(1,241);
             lcd_putchar('A',BLACK,WHITE);
              lcd_gotoxy(4,241);
             lcd_putchar('S',BLACK,WHITE);
              lcd_gotoxy(7,241);
             lcd_putchar('D',BLACK,WHITE);
              lcd_gotoxy(9,241);
             lcd_putchar('F',BLACK,WHITE);
              lcd_gotoxy(12,241);
             lcd_putchar('G',BLACK,WHITE);
              lcd_gotoxy(15,241);
             lcd_putchar('H',BLACK,WHITE);
              lcd_gotoxy(18,241); 
             lcd_putchar('J',BLACK,WHITE);
              lcd_gotoxy(20,241);
             lcd_putchar('K',BLACK,WHITE);
              lcd_gotoxy(23,241);
             lcd_putchar('L',BLACK,WHITE);
              lcd_gotoxy(25,241);
             lcd_putchar(';',BLACK,WHITE);
             lcd_gotoxy(28,241);
             lcd_putchar(')',BLACK,WHITE);
           
               lcd_gotoxy(1,243);
             lcd_putchar('Z',BLACK,WHITE);
              lcd_gotoxy(4,243);
             lcd_putchar('X',BLACK,WHITE);
              lcd_gotoxy(7,243);
             lcd_putchar('C',BLACK,WHITE);
              lcd_gotoxy(9,243);
             lcd_putchar('V',BLACK,WHITE);
              lcd_gotoxy(12,243);
             lcd_putchar('B',BLACK,WHITE);
              lcd_gotoxy(15,243);
             lcd_putchar('N',BLACK,WHITE);
              lcd_gotoxy(18,243); 
             lcd_putchar('M',BLACK,WHITE);
              lcd_gotoxy(20,243);
             lcd_putchar(',',BLACK,WHITE);
              lcd_gotoxy(23,243);
             lcd_putchar('.',BLACK,WHITE);
              lcd_gotoxy(25,243);
             lcd_putchar('?',BLACK,WHITE);
             lcd_gotoxy(28,243);
             lcd_putchar('!',BLACK,WHITE);
            
             lcd_gotoxy(7,1); 
              lcd_puts("typed text : ",BLACK,WHITE);
             lcd_draw_rectangle(50,40,185,100,BLACK);
            
             lcd_gotoxy(20,10); 
              lcd_puts("Save text ",BLACK,WHITE);
             lcd_draw_rectangle(158,155,236,185,BLACK);
            
   while (1)
      {        
            
           
             
      
      DDRA.0=1;        //-x
      DDRA.1=0;        //y
      DDRA.2=1;        //x
      DDRA.3=0;        //-y
      PORTA.0=0;
      PORTA.1=0;
      PORTA.2=1;
      PORTA.3=0;
      
      y=read_adc(1); 
      y=y/4.26;  
      itoa(y,stry);
     
       lcd_gotoxy(0,1);
      lcd_puts("X= ",RED,WHITE);
      lcd_puts(stry,RED,WHITE);
     
      DDRA.0=0;
      DDRA.1=1;
      DDRA.2=0;
      DDRA.3=1;
      PORTA.0=0;
      PORTA.1=1;
      PORTA.2=0;
      PORTA.3=0;
      x=read_adc(2);
      x=x/3.19;  
      itoa(x,strx);   
   
      lcd_gotoxy(0,0);    
      lcd_puts("Y= ",RED,WHITE);
      lcd_puts(strx,RED,WHITE); 
     
        //-----------------------------------------------
         lcd_gotoxy(j,3);    
        
          if(y<25 && y>19 && x==10 ){               
          lcd_putchar('Q',BLACK,WHITE);
           j++; 
         }  
        
         if(y<25 && y>19 && x>11 && x<15){               
          lcd_putchar('W',BLACK,WHITE);
          j++;
         }
       
         if(y<25 && y>19 && x<19 && x>15){               
         lcd_putchar('E',BLACK,WHITE);
         j++; 
         }   
       
          if(y<25 && y>19 && x<23  && x>19 ){               
          lcd_putchar('R',BLACK,WHITE);
           j++;  
         }
        
          if(y<25 && y>19 && x>23 && x<27){                
          lcd_putchar('T',BLACK,WHITE);
           j++;
         }
       
         if(y<25 && y>19 && x>28 && x<32){               
         lcd_putchar('Y',BLACK,WHITE);
          j++;
         }
        
          if(y<25 && y>19 && x>32  && x<37){               
          lcd_putchar('U',BLACK,WHITE);
          j++;
         } 
        
         if(y<25 && y>19 && x<41 && x>37){               
          lcd_putchar('I',BLACK,WHITE);
          j++;
         }
       
         if(y<25 && y>19 && x<45 && x>41){              
         lcd_putchar('O',BLACK,WHITE);
         j++;
         }
        
          if(y<25 && y>19 && x<49  && x>45 ){              
          lcd_putchar('P',BLACK,WHITE);
          j++; 
         }  
        
         if(y<25 && y>19 && x<41 && x>49){               
          lcd_putchar('(',BLACK,WHITE);
          j++;
          }
        //----------------------------------------------
      }      
  }     
      
void init()
{

PORTA=0x00;
DDRA=0x00;
PORTB=0x00;
DDRB=0x00;
PORTC=0x20;
DDRC=0xFF;
PORTD=0x00;
DDRD=0xFF;


// Analog Comparator initialization
// Analog Comparator: Off
// Analog Comparator Input Capture by Timer/Counter 1: Off
ACSR=0x80;
SFIOR=0x00;
// ADC initialization
// ADC Clock frequency: 125.000 kHz
// ADC Voltage Reference: AREF pin
// ADC Auto Trigger Source: None
ADMUX=ADC_VREF_TYPE & 0xff;
ADCSRA=0x83;
}
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