At my wits end - Electronic Circuits Projects Diagrams Free

zanes · 29th April 2008, 02:43 PM

As mentioned in my previous thread, I'm having real trouble with my photovore.I'm using a PIC16F54 connected to 2 h bridges made of BD139 and BD140s. When I tell the PIC to turn on both h bridges (ie, keep two pins high) it's all fine and dandy. When I load up code to take inputs from 2 LDR/resistor dividers and turn on the motors appropriately, nothing happens, although if I spin the motor shaft the motor will turn and run, but slowly. I've rewritten the code, changed pins, tried a BC337 pre amplifier and tried phototransistors as sensors all to no effect.
Boosting the h bridge voltage to 9v had some effect, but a Nicad 9v pack is far too large for my bot. The PIC is running at 5v, as is the LDR sensors. Trying PICKIT2 +5v and a regulated 5v supply from a PP3 made no difference. The hbridge is running at 3volts.
I know it sounds childish, but I'm really beginning to regret ever starting this project. I've had lots of problems, but I've solved them. I've been working on this one for a day, and I've had no luck. It's the last thing in the way of this project, and it's getting to me.

Pommie · 29th April 2008, 02:47 PM

Can you post the code? Put [code] before it and [/code] after it so it keeps it's format.

Mike.

zanes · 29th April 2008, 02:57 PM

Code:

;*****
;Alex E-S
;27/4/2008
;Version 2 (original did not work at all)
;Revision 3 (reassigned ports to simplify full h-bridge implementation later)
;for PIC 16F54
;Clock 2.4576MHz
;Function: control file for lightseeking robot.

	list P = 16F54
	include "c:\PIC\P16F5X.inc"
	__config  _XT_OSC&_WDT_OFF&_CP_OFF
;==========

;Declarations:

rmotfor equ 00h
rmotrev equ 01h
lmotfor equ 00h
lmotrev equ 01h
rightldr equ 02h
leftldr equ 03h
porta 	equ 05h
portb   equ 06h
	org 1FFh
	goto Start
	org 0
	
	
;==========

; Subroutines:

Init
	clrf porta ;Resets porta
	clrf portb ;Resets portb
	movlw b'1100' ;Sets porta
	tris porta 		;as outputs
	movlw b'00000000' ;sets portb
	tris portb		  ;as i/o
	retlw 0		    ;resets working reg to 0

;==========when dark sensors go low, when light sensors go high
;Program Start
Start 
	call Init
Main
	bcf porta,rmotfor ;turns both 
	bcf porta,lmotfor ;motors off
	btfsc portb,rightldr ;tests light on right LDR
	goto rightlight		;if light,goto rightlight 
	btfsc portb,leftldr ;tests light on left LDR
	goto leftlight		;if light,goto left light
	goto Main
rightlight
	btfsc portb,leftldr ;tests if light on left LDR too
	goto bothlight		;if there is,goto bothlight
	bsf porta,lmotfor ;if not turns on left motor to turn towards light
	goto Main
leftlight
	btfsc portb,rightldr ;tests if light on left LDR too
	goto bothlight 		 ;if there is,goto bothlight
	bsf porta,rmotfor ;if not turns on right motor to turn towards light
	goto Main
;nolight			;behaviour if no light (rotate set amount?(90 degrees?)
	;goto Main
;	bsf porta,rightmotor  initially no action,call from Main when developed.
bothlight		;behaviour if both light
	bsf porta,rmotfor ;turns on 
	bsf porta,lmotfor  ;both motors (later for set time?)
	goto Main
	END

**Nigel Goodwin** · 29th April 2008, 02:57 PM

For a start remove the pic entirely, and test the H-bridge - manually connect the inputs to 5V or 0V with a 1K resistor and see how the motor moves then.

zanes · 29th April 2008, 03:01 PM

Done that-full operation, works off pickit supply too.

Pommie · 29th April 2008, 03:07 PM

You seem to have both the left and right motor forward signals on PortA,0 and the two reverse signals on PortA,1. How is your H-Bridge connected to your pic?

Mike.

zanes · 29th April 2008, 03:57 PM

Ah, that's a relic from troubleshooting, the left motor is connected to porta 0 and 1. Changing that makes no difference, it was merely something I was trying. H-bridge is connected directly to the PIC (was that what you were asking?)

ericgibbs · 29th April 2008, 04:35 PM

Quote:

Originally Posted by zanes

Ah, that's a relic from troubleshooting, the left motor is connected to porta 0 and 1. Changing that makes no difference, it was merely something I was trying. H-bridge is connected directly to the PIC (was that what you were asking?)

hi Zanes,
Just put your program on the Oshonsoft sim, had to use 16F84 for sim.

You are setting PORTB as output, yet you are testing for LDR's on the PORTB inputs.

I have had to move the 'org' 's as the program crashes with a stack fault.!

Hope this helps.

zanes · 29th April 2008, 04:49 PM

Thanks. Where did you move the orgs to? I'll try it tomorrow probably, I've had enough for today.

ericgibbs · 29th April 2008, 04:58 PM

Quote:

Originally Posted by zanes

Thanks. Where did you move the orgs to? I'll try it tomorrow probably, I've had enough for today.

Hi,

org 0x0;1FFh
goto Start
org 0x04

The declarations are causing problems in the right/left.
For test do this, use numbers in place of all these labels
bsf porta,0; rmotfor ;turns on
bsf porta,1; lmotfor ;both motors (later for set time?)

And it all works OK...

zanes · 29th April 2008, 05:05 PM

So because I've defined two things as "01" and "00" it's having problems? Or shouldn't I be using equ for this stuff (I have no problems using numbers, it just helped me write and think about the code)

ericgibbs · 29th April 2008, 05:32 PM

Quote:

Originally Posted by zanes

So because I've defined two things as "01" and "00" it's having problems? Or shouldn't I be using equ for this stuff (I have no problems using numbers, it just helped me write and think about the code)

hi,
I didnt dig too deep why, but the problem was that A.0 was the output selected for both rmotfor and lmotfor.
The correct subr was entered but it was always the A.0 bit that was set..?

Likewise when it was the both subr it was still only A.0.

When I changed these two labels to their numeric value, the prog worked OK.

Does this help.?

Dont forget to TRISB as 0xff, Inputs

zanes · 29th April 2008, 08:38 PM

Hmmm... I think I only changed that as a troubleshooting attempt, and then changed part of the program back. I'll try it, and change those orgs. I also need to reread my pic book it seems....

ericgibbs · 30th April 2008, 07:55 AM

Quote:

Originally Posted by zanes

Hmmm... I think I only changed that as a troubleshooting attempt, and then changed part of the program back. I'll try it, and change those orgs. I also need to reread my pic book it seems....

Hi zanes,
Post the latest program and I will re-run it in the Oshonsoft Sim.

As I have said, my Sim dosn't have a 16F54 in its options, but the 16F84 option seems to work OK.

zanes · 30th April 2008, 02:48 PM

Right, here we go. Still the same, LEDs connected to the outputs work perfectly, exactly how I programmed then. When I made a mistake in reworking the code, so one hbridge was on all the time, the motor behaved perfectly. It almost as if either a; The microcontroller is not giving full voltage when acting as a decision maker, or b; The code is acting as a very crude PWM, which is dropping the voltage supplied to the h-bridge, which I find unlikely. Anyway, here's the latest version of the code;

Code:

;*****
;Alex E-S
;27/4/2008
;Version 2 (original did not work at all)
;Revision 4 (rework)
;for PIC 16F54
;Clock 2.4576MHz
;Function: control file for lightseeking robot.

	list P = 16F54
	include "c:\PIC\P16F5X.inc"
	__config  _XT_OSC&_WDT_OFF&_CP_OFF
;==========

;Declarations:

porta 	equ 05h
portb   equ 06h
	org 0x0;1FFh
	goto Start
	org 0x04
	
	
;==========

; Subroutines:

Init
	clrf porta ;Resets porta
	clrf portb ;Resets portb
	movlw b'1100' ;Sets porta
	tris porta 		;as i/o
	movlw b'00000000' ;sets portb
	tris portb		  ;as outputs
	retlw 0		    ;resets working reg to 0

;==========when dark sensors go low, when light sensors go high
;Program Start
Start 
	call Init
Main
	bcf porta,0 ;turns both 
	bcf porta,1
	bcf portb,0 ;motors off
	bcf portb,1
	btfsc porta,2 ;tests light on right LDR
	goto rightlight		;if light,goto rightlight 
	btfsc porta,3 ;tests light on left LDR
	goto leftlight		;if light,goto left light
	goto Main
rightlight
	btfsc porta,3 ;tests if light on left LDR too
	goto bothlight		;if there is,goto bothlight
	bsf portb,0 ;if not turns on left motor to turn towards light
	goto Main
leftlight
	btfsc porta,2 ;tests if light on right LDR too
	goto bothlight 		 ;if there is,goto bothlight
	bsf porta,0 ;if not turns on right motor to turn towards light
	goto Main
;nolight			;behaviour if no light (rotate set amount?(90 degrees?)
	;goto Main
;	bsf porta,rightmotor  initially no action,call from Main when developed.
bothlight		;behaviour if both light
	bsf porta,0 ;turns on 
	bsf portb,0  ;both motors (for set time?)
	goto Main
	
	END

29th April 2008, 02:43 PM	(permalink)
zanes Experienced Member	At my wits end As mentioned in my previous thread, I'm having real trouble with my photovore.I'm using a PIC16F54 connected to 2 h bridges made of BD139 and BD140s. When I tell the PIC to turn on both h bridges (ie, keep two pins high) it's all fine and dandy. When I load up code to take inputs from 2 LDR/resistor dividers and turn on the motors appropriately, nothing happens, although if I spin the motor shaft the motor will turn and run, but slowly. I've rewritten the code, changed pins, tried a BC337 pre amplifier and tried phototransistors as sensors all to no effect. Boosting the h bridge voltage to 9v had some effect, but a Nicad 9v pack is far too large for my bot. The PIC is running at 5v, as is the LDR sensors. Trying PICKIT2 +5v and a regulated 5v supply from a PP3 made no difference. The hbridge is running at 3volts. I know it sounds childish, but I'm really beginning to regret ever starting this project. I've had lots of problems, but I've solved them. I've been working on this one for a day, and I've had no luck. It's the last thing in the way of this project, and it's getting to me.

29th April 2008, 02:57 PM	(permalink)
Nigel Goodwin Super Moderator	For a start remove the pic entirely, and test the H-bridge - manually connect the inputs to 5V or 0V with a 1K resistor and see how the motor moves then. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

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29th April 2008, 02:47 PM	(permalink)
Pommie Experienced Member	Can you post the code? Put [code] before it and [/code] after it so it keeps it's format. Mike.

29th April 2008, 03:01 PM	(permalink)
zanes Experienced Member	Done that-full operation, works off pickit supply too.

29th April 2008, 03:07 PM	(permalink)
Pommie Experienced Member	You seem to have both the left and right motor forward signals on PortA,0 and the two reverse signals on PortA,1. How is your H-Bridge connected to your pic? Mike.

29th April 2008, 03:57 PM	(permalink)
zanes Experienced Member	Ah, that's a relic from troubleshooting, the left motor is connected to porta 0 and 1. Changing that makes no difference, it was merely something I was trying. H-bridge is connected directly to the PIC (was that what you were asking?)

29th April 2008, 04:49 PM	(permalink)
zanes Experienced Member	Thanks. Where did you move the orgs to? I'll try it tomorrow probably, I've had enough for today.

29th April 2008, 05:05 PM	(permalink)
zanes Experienced Member	So because I've defined two things as "01" and "00" it's having problems? Or shouldn't I be using equ for this stuff (I have no problems using numbers, it just helped me write and think about the code)

29th April 2008, 08:38 PM	(permalink)
zanes Experienced Member	Hmmm... I think I only changed that as a troubleshooting attempt, and then changed part of the program back. I'll try it, and change those orgs. I also need to reread my pic book it seems....