Having problem with ADC display on PIC18F4520 LCD

[caramelz]

Hi, I'm having some problems on interfacing ADC with LCD display. The main purpose of using ADC is because I need to read the voltage of the batteries and transfer it, and display to LCD. I'm using MCC18 compiler. Please guide or help me!

include <p18f4520.h>
#include <delays.h>
#include <stdlib.h> 


void Init_LCD(void);    //Initialise the LCD
void W_ctr_8bit(char);  //8-bit Control word for LCD
void W_data_8bit(char); //8-bit Text Data for LCD


ADCON0=0b00000001;    
ADCON0bits.GO = 1;        // Start ADC 
Delay10TCYx(5); //give channel time to initiliase 
while(ADCON0bits.DONE); // Wait for conversion to finish. 
counts=ADRESH*255 +ADRESL; 
//for 3.62 volts, expect a count of 741 
millivolts = (counts * 1.367)/100; //gives a result of 3630.9 
    Init_LCD();
    W_ctr_8bit(0x80);
    for(i=0;i<8;i++)
    W_data_8bit(MESS3[i]);
    W_ctr_8bit(0x8C);
    W_data_8bit('V');


itoa(millivolts,Distance1); //(int value, char * str, int base); 


W_ctr_8bit(0x89);        
while(Distance1[i])
    {
        W_data_8bit(Distance1[i]);
        i++;
    }

[Click_here]

Are you trying to measure the voltage of the batteries that are running the PIC?

If so, that could be a problem.

[caramelz]

Are you trying to measure the voltage of the batteries that are running the PIC?

If so, that could be a problem.

nope. i'm making a batteries charging system. so measuring the voltage of the rechargeable batteries is the big problem i'm facing

[Salem]

> itoa(millivolts,Distance1); //(int value, char * str, int base);
Are you suggesting you have some hacked version of itoa() which doesn't have a base parameter?
Or are you just ignoring warnings, and feeding itoa a garbage base value?

How is Distance1 declared?
char *Distance1; // wrong!

char Distance1[20]; // Right!

> W_data_8bit(MESS3[i]);
Does this work? Do you see the message?
If not, then we need to get your printing a simple string working.

> millivolts = (counts * 1.367)/100; //gives a result of 3630.9
What type is millivolts?
Your odd comment at the end suggests that it may not be an integer (see your use of itoa later on).

Try say something like
millivolts = 1000; // millivolts = (counts * 1.367)/100; //gives a result of 3630.9
Do you see 1000 converted and printed OK?
Yes - the problem is in the ADC or the maths
No - the problem is in the printing / conversion.

Work through these steps and try and come up with a decent analysis of what works and what doesn't.

[caramelz]

Hi Salem. Thanks for the guide, I will work on it. if i declare char MESS[]="welcome"; and display it with W_data_8bit(MESS[i]); . the LCD is able to display. but when i tried using it on itoa, it is not able to display anything.

[stahta01]

> itoa(millivolts,Distance1); //(int value, char * str, int base);
Are you suggesting you have some hacked version of itoa() which doesn't have a base parameter?
Or are you just ignoring warnings, and feeding itoa a garbage base value?

From my own MPLAB C18 stdio.h file.

char *itoa (auto int value, auto char *s);

So, Microchip uses a non-standard prototype for itoa that does only base 10 conversion.

What type is millivolts?

The above is what I would like answered in Salem's list of question; since if it is wrong. I would suspect the approx. results being reported.

Tim S.