[SOLVED] PIC18F2550 RB5 pin not functioning

[denujith]

Hi Everybody,

I have connected 4 LEDs to RB7, RB6, RB5 and RB4 pins of PIC18F2550 via a 470 ohm resistor. My intension is to blink LED one after the other.

My C code is:

#include <pic18.h>
#include <18f2550.h>

#pragma config FOSC = INTOSCIO_EC
#pragma config WDT = OFF

void delay (unsigned int interval){
	unsigned int i;
	for ( i=0; i!=interval; i++ );
}

void main(){
	char dir;
	TRISB = 0;
	PORTB = 0;
	while(1)
	{
		RB4 = 0;
		RB7 = 1;
		delay(2000);
		RB7 = 0;
		RB6 = 1;
		delay(2000);
		RB6 = 0;
		RB5 = 1;
		delay(2000);
		RB5 = 0;
		RB4 = 1;
		delay(2000);
	}		
}

But LED connected to RB5 is not blinking. Can any one of you please let me know any reason as to why RB5 LED is not blinking?

Regards,
/Lakmal

 

[john blue]

Try using LATB,5 =1;

PORT registers read back the instantaneous pin state and the LAT registers read back what each pin was last written to. Look up "read/modify/write" to see why this matters

 

[denujith]

LATB5=1; didn't solve the problem. can you please explain more about "read/modify/write"?

 

[spiralbrain]

do you disconnect your programmer when you run this? its the PGM pin sometimes its held high or low by programmers like PICKIT2

 

[denujith]

Yes I disconnected. Should I have to set CONFIG bits?

 

[spiralbrain]

yes check the LVP bit, if it is set, all RB5's functions are disabled. Page 117 of the datasheet also page 312.

 

[denujith]

These are my config bits:

#pragma config FOSC = INTOSCIO_EC
#pragma config WDT = OFF
#pragma config LVP = OFF
#pragma config BOR = ON
#pragma cinfig PWRT = ON

But, still it doesn't work

 

[spiralbrain]

upload the hex file please.

 

[denujith]

It doesn't allow me to upload .hex files. says: Invalid File Type.

 

[spiralbrain]

zip it, or change extension

 

[denujith]

I uploaded .hex as .zip

 

[denujith]

This is the source file.

 

[spiralbrain]

the hex is perfectly alright, here is the simulation:



double check your hardware, last guess is the Port pin is faulty. Try another PIC.

 

[denujith]

Thank you a lot for your effort. I'll replace the PIC and try again.

 

[denujith]

This is my hardware setup. Just to make sure everything else is OK.

 

[spiralbrain]

just a thought: using a common resistor for all the LED's is a bad practice, each one must have its own resistor to limit current. in your case only one LED lights at a time so its fine.

 

[denujith]

Hi spiralbrain,

I seems I have to replace PIC.
Anyway, Thank you a lot for your time and effort spent helping me.

/Lakmal

 

[john blue]

I remember you must do something to the LAT rather that the port directly. If not if will not work.

Can you try this and see whether it works:

LATB.5 = 1;

 

[denujith]

Cannot use LATB.5 = 1; Compile errors. I am planning to test on a new PIC. Thank you all for your help.