decoding quadrature encoders

[ice]

Thanks Luciano,
Im read up the pbp manual and others for interrupts...
..however my test program isnt compiling..

		wsave 	VAR BYTE $20 system				'bank0
		wsave1 	VAR BYTE $a0 system				'bank1
		'wsave2 	VAR BYTE $120 system		'bank2
		'wsave3 	VAR BYTE $1a0 system		'bank3
		ssave 	VAR BYTE bank0 system
		psave 	VAR BYTE bank0 system
		led 	VAR PORTB.1
		
		GoTo start_0 					' Skip around interrupt handler	


		DEFINE INTLHAND myint			' DEFINE INTERRUPT handler
		Asm
myint:	bsf _led 						; Turn on LED (for example)
		bcf intcon.0
				
		retfie
		EndAsm
    
	
		
										' Assembly language INTERRUPT handler    
		

    
start_0:
		
		TRISB=%11111101	
		Low led 						' Turn LED off
		INTCON = %10001000				' Enable INTERRUPT ON PORTB.0
        
	
loop: 		GoTo loop 						' Wait here till interrupted

1> compile error "DEFINE INTHAND myint"
....undefined symbol myint
however if i relpace it with DEFINE INTLHAND myint,(which is only for th 18x series),it complies ok..

2>im using a 16F873A,which has a 4K flash,meaning 4 banks...
according to the PBP manual, i have to define wsave,wsave1,wsave2,wsave3...
it takes in wsave and wsave1...but when i declare wsave2 and wsave3..it gives a RAM_END 255 error

3>i cannot get the LED to blink either by using the int0 or the Interr On change<4:7>

[ice]

Hmmm..
I got the program to compile and work with interrupts on portB<4:7>

Ill try to implement the quadrature decoding in assembly now..

[Luciano]

Example from:
http://www.microengineeringlabs.com/...manual/9_0.htm

Luciano

	' Assembly language interrupt example

	led	 var	PORTB.1

	wsave var	byte $20 system
	ssave var	byte bank0 system
	psave var	byte bank0 system


	Goto start	' Skip around interrupt handler

	' Define interrupt handler
	define INTHAND myint

	' Assembly language interrupt handler
	asm
	; Save W, STATUS and PCLATH registers
	myint	movwf	wsave
		swapf	STATUS, W
		clrf	STATUS
		movwf	ssave
		movf	PCLATH, W
		movwf	psave

	; Insert interrupt code here
	; Save and restore FSR if used

		bsf	_led	; Turn on LED (for example)

	; Restore PCLATH, STATUS and W registers
		movf	psave, W
		movwf	PCLATH
		swapf	ssave, W
		movwf	STATUS
		swapf	wsave, F
		swapf	wsave, W
		retfie
	endasm

	' PICBASIC PRO™ program starts here
	start: Low led	' Turn LED off

	' Enable interrupt on PORTB.0
		INTCON = %10010000

	loop:	Goto loop	' Wait here till interrupted

[ice]

Thanks Luciano,
But it's the same program as in the datasheet...
Im now trying to write the decoding program in assembly..

[Luciano]

Rotary encoder in assembly for 16F84:
http://emp.byui.edu/fisherr/EET255/encdr.asm

Luciano

[ice]

Luciano,
I added the code from the lin you posted..
I'm using interrupt on INT0 connected to channel A..


I'm able to count and detect directions..with 1 big problem

i cannot monitor or dispaly the counts either using LCDout or software serial to hyperterminal.
it's good for 2 seconds and then the whole LCD screen corrupts
...is it because the LCDout line is being interrupted by the encoder
...if i disable/enable interrupts within the LCDout line..i lose encoder counts


in the code..i use 2 leds connected to portB.6,7 to show direction.
LOOP is my main program

my code is below

		GoTo start 					' Skip around interrupt handler	


		DEFINE INTHAND display			' DEFINE INTERRUPT handler
		Asm
display 
		movwf	wsave
		swapf	STATUS, W
		clrf	STATUS
		movwf	ssave
		movf	PCLATH, W
		movwf	psave
		
	
		;;;bsf _led 						; Turn on LED (for example)
		;new=PORTB & %11000000

		;Get intitial input from ENCODER & put the value in OLD.
     	movf	PORTB,W
     	movlw   _old

     	;Strip off all but the last  2 LSBs in OLD.
		movlw	0x03				;Create bit mask for 2 LSBs (bits 6 & 7). 11000000
     	andwf	_old,F          	;Zero bits 0 thru 6.

		;Read latest input from ENCODER & put the value in NEW.
    	movf    PORTB,W
     	movwf	_new

     	;Strip off all but the 2 LSBs in OLD.
		movlw	0x03				;Create bit mask for 2 LSBs (bits 6 & 7). 11000000
     	andwf   _new,F     			;Zero bits 0 thru 6.





     	movf	_new,W				;Move the contents of NEW to TEMP and OLD to W
     	movwf   _temp      			;in order to compare them with XOR.
     	movf    _old,W     
     	xorwf   _temp,F    			;XOR previous inputs (in W) with latest inputs 
                         			;(in TEMP) to see if they are equal.
     	btfsc   STATUS,Z  			;Test result and skip next line if 0.
     	
     	GoTo	rtrn				;Result is 0.  Previous inputs equal latest 
                         			;inputs.  Rotary encoder did not move.  Return
                         			;to loop
     	
    	;Result is 1.  Rotary encoder moved.  Determine direction.
     	bcf		STATUS,C  			;Clear the carry bit in the status register and
     	rlf     _old,F     			;left shift it into OLD to align bit0 of OLD
                         			;with bit 1 of NEW.
     	movf    _new,W     			;Move the contents of NEW to W in order to XOR.
     	xorwf   _old,F    			;XOR previous inputs (in OLD) with latest
                         			;inputs (in W) to determine CW or CCW.
     	btfsc   _old,1     			;Test bit 1 of result (in OLD).  Skip next line
                         			;if it is 0 (direction is CCW).
     	GoTo    Up        			;Bit is 1 (direction is CW).  Go around Down
     	
     	
     	
Down
     	;Decrements COUNTER because encoder moved CCW.

     	decf	_enc_counter,F 
     	bsf		_led
     	GoTo    rtrn  				;Branch around UP.

Up
     	;Increments COUNTER because encoder moved CW.

     	incf    _enc_counter,F
     	bsf		_led2     	
                         			;and increment counter.

     	
rtrn	bcf intcon.1				; clear interrupt flag 
	    
	    ; Restore PCLATH, STATUS and W registers
		movf	psave, W
		movwf	PCLATH
		swapf	ssave, W
		movwf	STATUS
		swapf	wsave, F
		swapf	wsave, W
		retfie
		EndAsm
 
start:
		
		'SerOut PORTC.0,T9600,[#enc_counter,10,13]
		TRISB=%00111111
		TRISC=%00000000
		Low led 	
		Low led2				' Turn LED off
		INTCON = %10010000		' Enable INTERRUPT ON portb INT0
		option_reg=%01110000
      	
loop: 	
		'INTCON = %00000000
		'LCDOut $fe,1,DEC enc_counter
		'Pause 4
		'INTCON = %10010000
		Low led
		Low led2
		GoTo loop

[Luciano]

Hi!

If you use INT0 you will lose encoder counts.
See my Incremental quadrature encoder direction drawing.
(File encoder.zip posted the 9th April 2005, 13:44).

The two encoder signals A/B have to be connected to two of
the PINs RB<7:4> which have an interrupt-onchange feature.

* * *
When I post a code sample, the code is well formatted and
there are no dead commented statements.(I do my best).
Do you think that people on this forum will spend time
reading your code if it is not formatted?

* * *

See thread LCDOUT & interrupts.
http://www.picbasic.co.uk/forum/show...dout+interrupt

* * *

Luciano