ADC on 18F4525 coded in C langage under MPLAB (C18)

[lionkid]

c18 adc

Hi all!

This is my first topic because i'm new in PIC programming. I have C langage knowledge and i want to handle a new device which is a PIC.

I've done the hardware programmer Schaer+ and i use Winpic for programming my code, but it seems that it doesn't work! I've tested my pic with a led blinking and it works. So, i'm sure that my problem is due to the ADC use...

Here is my code (mixed with french, because i'm french) :

#include <p18f4525.h>
#include <adc.h>
#include <delays.h>

#pragma config WDT = OFF

void main(void)
{
	int result=0;
	float tension=0;
	/**************** CONFIGURATION DE L'OSCILLATEUR DU PIC *********************/
	
	OSCCONbits.SCS1=1;				// Use of the internal oscillator at 8Mhz frequency
	OSCCONbits.SCS0=1;				// Utilisation de l'oscillateur interne du PIC
	
	OSCCONbits.IRCF0=1;				//
	OSCCONbits.IRCF1=1;				// Fréquence d'utilisation de l'oscillateur = 8Mhz.
	OSCCONbits.IRCF2=1;				//
	
	/****************************************************************************/	
	
	
	TRISEbits.TRISE0=1;				// Configure la patte RE0 en entrée pour le capteur de lumière (AN5), RE0 as input for the light sensor
	TRISEbits.TRISE1=0;				// Configure la patte RE1 en sortie pour la LED. (AN6), RE1 as output for the LED.
	
	OpenADC(ADC_FOSC_2 & ADC_RIGHT_JUST & ADC_12_TAD,
			ADC_CH5 & ADC_INT_OFF & ADC_REF_VDD_VSS,
			ADC_6ANA);	// Open the ADC in the Channel 5 (RE0, AN5) with +5V reference level (=Vdd) and 0V as Vss.
	while(1)		
	{
		Delay10TCYx( 5 );
		ConvertADC();
		while(BusyADC());
		result=ReadADC();
		tension = (result*5)/1023;
		if(tension>=1) PORTEbits.RE1=1;	// Allume la LED si activitée detectée sur CAN, LED is ON if Voltage supplied by the sensor is greater than 1Volt.
		if(tension<1) PORTEbits.RE1=0;	// Eteint la LED si tension inférieure à 1Volt, LED is OFF otherwise.
	}
	CloseADC();	// In reality, the ADC is never closed due to the while(1)...
}

So, what's wrong? In my test board i've put the MCLR (bar)pin on +Vdd, the Vdd pin to +5V (given by a 78M05), Vss pin to the ground (of the 78M05), then i've got my light sensor on the RE0 pin which is mounted like that :

+5V
|
|
[sensor]
|--------------> RE0
| |
| | 10k resistor
|
GND

for my LED (3mm, 2mA @ 1.9V), i've got :

RE1
|
|
| | 1.5k
| |
|
LED
|
GND.

Have i made any mistakes? I'm discouraged because the Schaer+ programmer have taken a lot of time for working (soft + hard configuration) and now the PIC doesn't want to make what i want... :'(

PS : I don't use any external oscillator (no quartz), should i? (more stability ??).
PS2 : Is my PIC dead??

Regards,

lionkid.

 

[marcotulli]

18f4525

Hi,

I don't know if you are still waiting for an answer on this topic ....
I think the problem is in :
tension = (result*5)/1023; with result being an (int) and tension a (float) and the you check if tension is >=1 or <1.
I think you will get always <1 and so the LED OFF always.
Try to use result (int) only and then
if result is grater then or equal to 205 LED ON else LED OFF.

Regards,

mt