Flashing an LED problem...

[RobertD]

Hi folks. I'm using Pommie's program to flash an LED, first time it worked, and I have one chip that flashes, but the same programs on the next two chips hangs after a couple or three minutes, and the LED stops flashing. The same program I used is this one modified slightly for time. Does anyone know why it stops flashing after three minutes?

LIST p=16F88
include "P16F88.inc"
__config _CONFIG1, _WDT_OFF & _INTRC_IO & _MCLR_ON

cblock 0x20
;variables go here
d1
d2
d3
endc

org 0x0000 ;start of program
init
bsf STATUS,RP0 ;bank 1
movlw 0x42 ;8MHz internal osc
movwf OSCCON
movlw 0x07 ;turn comparators off
movwf CMCON
clrf ANSEL ;all pins digital
movlw 0x00 ;all pins outputs
movwf TRISA ;& 0x7f
movwf TRISB
bcf STATUS,RP0 ;select bank 0

main bsf PORTA,1
call delay
bcf PORTA,1
call delay
goto main

delay movlw 0x15
movwf d1
movlw 0x74
movwf d2
movlw 0x01
movwf d3
delay_0 decfsz d1,f
goto dd2
decfsz d2,f
dd2 goto dd3
decfsz d3,f
dd3 goto delay_0
return

end

 

[blueroomelectronics]

Looks fine, nothing looks like it would overflow the stack or stop after 3 minutes.
movlw 0x42 ; is 1MHz (0x72 = 8)

PS use the code "#" button tags instead of quotes as it retains the formatting.

 

[RobertD]

The debugger runs through no problem. I just don't know why it stops flashing...?

I tried different delays, same thing happens.
And yes I didn't change the 1mhz time when I adjusted the clock.

 

[Mike - K8LH]

Hi Robert,

Add _LVP_OFF to your configuration line...

Have fun.

Mike

 

[RobertD]

I found it... I was running the LED directly from the chip, and it was running hot. I put a current limiting resistor and changed the LED now it's running OK...

Baby steps can be frustrating sometimes...

_LVP_OFF, what will this do?

No... it stopped again...

I'll add _LVP_OFF see if that works.

 

[blueroomelectronics]

Use your Firefly, it has the limiting resistors.

You can blink a Firefly LED easy
change your PORTA,1 to PORTA,6 in the main loop.

 

[RobertD]

Baby steps are frustrating...

but necessary.

LED is on again.

 

[RobertD]

Use your Firefly, it has the limiting resistors.

You can blink a Firefly LED easy
change your PORTA,1 to PORTA,6 in the main loop.

OK will do that. I do have to get into the firefly for the AD programming.

Like this you mean:

main
bsf PORTA,6
call delay
bcf PORTA,6
call delay
goto main

 

[RobertD]

Fantastic, I have LED 1 and 2 flashing....

I programmed in the ZIF socket and transferred the chip to the tutor position.

Actually 1 flashes red, and 2 flashes green.

 

[RobertD]

Now I have to program RB4 (switch 3) to trigger the AD read when pressed. So I can read the output on ADRESH/L, in MPLAB.

The firefly has all the features I need for my program, LED's, A/D inputs, and switches...

First step, make PORTB,4 input.

 

[blueroomelectronics]

You don't have to move it from the ZIF to the Tutor socket, just turn the tutor dip switch on and the 40,18 switches off.

 

[RobertD]

I program the chip while it's running? I thought I had to stop the program before programming it. That'swhy I took it out of tutor and put it in the ZIF

I programmed this to get the flashing LEDs to stop when pressing the switch RB0, but it's not working. I use weak pull-up to turn all PortB switches on, when I press RB0, I ground it, at least that's what I'm thinking, unless the switch RB0 is not connected to ground.


movlw B'11111111' ;make all Bports input
movwf TRISB
BCF OPTION_REG,7
bcf STATUS,RP0 ;select bank 0

main
bsf PORTA,6
call delay
bcf PORTA,6
call delay
btfsc PORTB,0
goto main
goto skip

(delay routine here)

skip nop
end

 

[Boomslang]

I have not used that hardware, so can't comment on the RB0 to ground (did you try btfss). Just one thing I usually do, instead of letting the program run to end, rather put in something like:
GOTO $-0 which will put it in an infinite loop at that position, and you can put the rest of your delay and other routines under that line.

How long are your delays, are you keeping the switch pressed in long enough?

 

[RobertD]

Hi Boomslang, I tried btfss, that didn't work either, I use a one second delay, and I press the switch long enough, I just have to keep pecking at it until it works... I should read the user manuel and get to know how the firefly is built, it really is a handy programmer.

 

[Boomslang]

Have a look at the circuit diagram to see how the pin is setup.

A way to make your code a bit smaller:

main
      btg     PORTA,6
      call     delay
      btfsc   PORTB,0
      goto    main
      goto $-0

(delay routine here)

 

[RobertD]

I looked at the diagram, and the pins are grounded, so I set up the option_reg and the btfsc and it works, when I press SW4, the led stops flashing, but it doesn't go to the end of the program, as I thought. It goes back on flashing. Now I have to test rb0 and rb1 if the bits are set, as the option_reg says they are.

This is very exciting for me, like a baby making his first baby steps... It's like a whole new world opened up.


(And yes, sw0 and sw1 work as well, so the pull up command works, as well as the pull downs... )

 

[blueroomelectronics]

You can program & debug it all while leaving it in circuit. Try it

 

[RobertD]

Thanks Bill,

I found out how to program it in circuit, very easy, just flip dip #4, it's a lot easier than moving the chip each time I change something in the code. I'm beginning to appreciate the versatility of the firefly. Next step is to get the A/D working. I got the switches working, so I want to trigger the AD with the switch, and go to adresh/L and read the results. I'll write a program by itself just for that.

 

[Pommie]

Your program is probably continuing because it is running through memory and restarting. The END instruction doesn't stop the program from running, you need a loop going to itself.

		movlw	B'11111111'	;make all Bports input
		movwf	TRISB
		bcf	OPTION_REG,7
		bcf	STATUS,RP0	;select bank 0

main
		bsf	PORTA,6
		call	delay
		bcf	PORTA,6
		call	delay
		btfsc	PORTB,0
		goto	main
		goto	skip

(delay		routine	here)

skip		nop
[COLOR="Blue"]Hang		goto	Hang[/COLOR]
		end

Anyway, it sounds like you're having fun.

Mike.

 

[RobertD]

Indeed I am enjoying this. So the program restarts and that's why it keeps on flashing after I press the switch. Is there anyway to have the program stop after it's done it's thing? Hanging the program doesn't stop it, some kind of power down interrupt perhaps?

Today, I'll try to get the AD working all by itself. Once I have it running by itself, I'll incorporate it to the routine.