Displaying ADC result on GLCD with C18 - Electronic Circuits Projects Diagrams Free

superbrew · 27th March 2008, 04:21 PM

Hello, I would like to display the result of an ADC conversion on my GLCD, but all I am getting is about 2.5 lines of garbage. Here is the code that I am using:
(GLCD functions created by Pommie and modified for my use)

Code:

#include <p18f2520.h>
#include <GLCD.h>
#include <adc.h>
#include <delays.h>
#include <stdlib.h>

#pragma config WDT = OFF, LVP = OFF, OSC = INTIO67

void main (void){
	int read;
	char adc_ret[10];
	
	ADCON1 = 0x0d;
	CMCON = 0x07;		// no comparators
	OSCCON = 0x70;
	TRISA = 0XFF;
	TRISC = 0x00;	
	
	//Setup
	Init_GLCD();
	OpenADC(ADC_FOSC_RC & ADC_LEFT_JUST & ADC_12_TAD,
		ADC_CH1 & ADC_INT_OFF & ADC_VREFPLUS_VDD & 
			ADC_VREFMINUS_VSS, 13);
	SetChanADC( ADC_CH1 );

	PutMessage((rom char*)"test");
	Delay10KTCYx(200);

	while (1){
		ConvertADC(); // Start conversion
		while( BusyADC() ); // Wait for completion
		
		read = 523;ReadADC();
		itoa(read,adc_ret);
		PutMessage((rom char*)adc_ret);
		Delay10KTCYx(250);
		SetPos(0,0);	
	}
        //This section of code works, I used it check ADC function
	/*ConvertADC();
	while(BusyADC());
	i = ReadADC();
	if(i<125)PORTC = 0b00000001;
	else if(i>126 && i<250)PORTC = 0b00000011;
	else if(i>251 && i<375)PORTC = 0b00000011;
	else if(i>376 && i<400)PORTC = 0b00000111;
	else if(i>401 && i<525)PORTC = 0b00001111;
	else if(i>526 && i<650)PORTC = 0b00011111;
	else if(i>651 && i<750)PORTC = 0b00111111;	
	else if(i>751 && i<875)PORTC = 0b01111111;
	else if(i>876 && i<1023)PORTC = 0b11111111;
	*/
}

Stepping through using MPLAB simulator, it seems to get hung up at the itoa function. Thanks

Pommie · 28th March 2008, 12:45 AM

Your problem is due to pointer differences. PutMessage expects a pointer to a rom string and you are passing it a ram variable.

You can get it working by doing,

Code:

    while (1){
        ConvertADC(); // Start conversion
        while( BusyADC() ); // Wait for completion
        read = 523;ReadADC();
        itoa(read,adc_ret);
        pos=0;
        while(adc_ret[pos])
            PutChar(adc_ret[pos++]);
        Delay10KTCYx(250);
        SetPos(0,0);    
    }

Not very elegant, but should work. Someday soon I'll get around to tidying those GLCD routines.

Mike.

superbrew · 28th March 2008, 03:46 AM

It works! Thanks again. Now I just have to figure out how to get the numbers on the display to be right justified.

Pommie · 28th March 2008, 04:02 AM

How about,

Code:

    while (1){
        ConvertADC(); // Start conversion
        while( BusyADC() ); // Wait for completion
        read = 523;ReadADC();
        itoa(read,adc_ret);
        SetPos(0,16-strlen(adc_ret));
        pos=0;
        while(adc_ret[pos])
            PutChar(adc_ret[pos++]);
        Delay10KTCYx(250);
        SetPos(0,0);    
    }

Mike.
Edit, forgot this was for a GLCD. The above is for a 16 character LCD. The principle is the same but it will be 128-strlen(adc_ret)*charwidth.

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28th March 2008, 12:45 AM	(permalink)
Pommie	Your problem is due to pointer differences. PutMessage expects a pointer to a rom string and you are passing it a ram variable. You can get it working by doing, Code: while (1){ ConvertADC(); // Start conversion while( BusyADC() ); // Wait for completion read = 523;ReadADC(); itoa(read,adc_ret); pos=0; while(adc_ret[pos]) PutChar(adc_ret[pos++]); Delay10KTCYx(250); SetPos(0,0); } Not very elegant, but should work. Someday soon I'll get around to tidying those GLCD routines. Mike. Last edited by Pommie; 28th March 2008 at 12:59 AM.

28th March 2008, 03:46 AM	(permalink)
superbrew	It works! Thanks again. Now I just have to figure out how to get the numbers on the display to be right justified.

28th March 2008, 04:02 AM	(permalink)
Pommie	How about, Code: while (1){ ConvertADC(); // Start conversion while( BusyADC() ); // Wait for completion read = 523;ReadADC(); itoa(read,adc_ret); SetPos(0,16-strlen(adc_ret)); pos=0; while(adc_ret[pos]) PutChar(adc_ret[pos++]); Delay10KTCYx(250); SetPos(0,0); } Mike. Edit, forgot this was for a GLCD. The above is for a 16 character LCD. The principle is the same but it will be 128-strlen(adc_ret)charwidth. Last edited by Pommie; 28th March 2008 at 04:15 AM.*