Problem with PIC external interrupts

[dotz89]

Hello all,
I'm using PIC18 Explorer Board's **broken link removed**
PIC18F8722 chip https://ww1.microchip.com/downloads/en/devicedoc/39646c.pdf
MPLAB C18 Compiler
I wrote this to test out the external ADC interrupt functions before I proceed on with other parts of my project

I'm quite new to MCUs, so pardon my noobish way of coding.

#include <p18f8722.h>
#include<delays.h>

/***************************
*   Device configuration   *
***************************/
#pragma config OSC = HSPLL	// Using 10 MHz crystal with PLL (max = 10MHz*4)
#pragma config FCMEN = OFF // Disable Fail-Safe Clock Monitor
#pragma config IESO = OFF  // Disable Oscillator Switchover mode
#pragma config PWRT = OFF  // Disable Power-up timer
#pragma config WDT = OFF   // Disable Watchdog timer
#pragma config MCLRE = ON  // Enable MCLR Enable
#pragma config LVP = OFF   // Disable low voltage ICSP

// Function declarations
void config_adc(void);


void config_adc(void)
{	
	TRISAbits.TRISA1 = 1; //AN1 = RA1 TRIS set to input
	TRISDbits.TRISD6 = 0; //LED output
	ADCON0 = 0b00000101; //AN1 selected
	ADCON1 = 0b00001101; //AN0-AN1 analog
	ADCON2 = 0b00001101;//left justified, 2Tad, Fosc 16

	//ADC Interrupts config
	INTCONbits.GIE = 1;  // enable interrupts
        INTCONbits.PEIE = 1; // enable peripheral interrupts.
	INTCONbits.INT0IE =1; //enables external interrupts
	PIE1bits.ADIE=1;//set the A/D converter interrupt enable bit. 1 is enable
   	PIR1bits.ADIF=0;//clear (initialise) A/D converter interrupt flag bit

}


// start ISR code
#pragma code isr = 0x08 // store the below code at address 0x08
#pragma interrupt isr

void isr (void)
{
    	
		if (PIR1bits.ADIF == 1) {
		LATDbits.LATD6 = 1; //switch on LED
		Delay1KTCYx(1);
		LATDbits.LATD6 = 0;		
		
		PIR1bits.ADIF=0;
		ADCON0bits.GO_DONE=1;//reset GO/DONE to start conversion
		}						
}

#pragma code // return to the default code section

void main (void)
{
   
    config_adc();
    ADCON0bits.ADON=1;  	//switch on the adc module forever, to add a pushbutton interrupt to switch off
    ADCON0bits.GO_DONE=1;	//Start conversion (in progress)
    while(1)
    {
   	
    }   
}

I just want to switch on my board, when I input an analog signal into RA1/AN1, an LED will light up, and power off after a few seconds.
This is a prelude to my other parts of the project, where I will use the ADC values to display, count etc.

My interrupt code is activated upon power on of the board, before I input my desired analog signal.
The LED at RD6 is switched on, and this command is only in the ISR, no where else in my main function.
I realised that if I were to change ADCON0bits.GO_DONE=1 to 0, the light will be switched off.
But it doesn't make sense to me to set it to 0 in the ISR, otherwise I will never be able to turn it on again while the program is running.

I went through it line by line drawing out link maps and all to see what is done but I cannot find the error in my code.
I ran the "Watch" window in MPLAB SIM and realised that LATD is set to 0x40 on processor reset. This corresponds to LAT.D6
I removed the LATD6=1 line yet it still shows 0x40.

Could any veteran point out my mistake to me please? Thank you.

 

[dotz89]

i don't get it it's still not working. that particular LED that's supposed to light up only when conversion is complete still lights up at the start.

i switched to polling method and this still occurs. This means that there is analog input that is converted, but the light doesnt delay and switch off as planned.

both methods worked according to plan in the simulator. the bits are only enabled when conversion is complete.