decoding quadrature encoders

[Luciano]

File attachment = Incremental quadrature encoder direction drawing.

Luciano

[ice]

Luciano>>
Thanks for the file..i figured out the logic of the "XOR"..

i included this in my code...[the counting up and counting down lines]

quad:
	new= PORTC & %00000011
	
start:
	old=new & %00000011 

again:
	new= PORTC & %00000011
	IF new=old Then again
	direction_bit=old.bit1 ^ new.bit0
	IF direct=0 Then  cw
	LCDOut $fe,1,"Last was CCW"
	counter=counter+1
	LCDOut $fe,$c0,DEC counter
	Pause 5
	GoTo start
		
cw:
	LCDOut $fe,1,"Last was CW"
	counter=counter-1
	LCDOut $fe,$c0,DEC counter
	Pause 5
	GoTo start

...I am able to see the counter going up and down as the motor changes it's direction..however the LCD line "last was cw/ccw"..keeps on flipping and never remains the same..even if the motor has moved in the same direction..

Im still working on it..and will keep u all posted...

monitor the 'value' variable. or modify it easily to have CW and CCW flag in one shot....

Thanks for the link M_e
..i'll be doing tht to take care of the above problem

[Luciano]

Try this code. (Not tested).

(Problem in your code: you use 'direction_bit' but also 'direct').

Luciano

	old_val VAR BYTE
	new_val VAR BYTE
	direction_bit VAR BIT
	enc_counter VAR WORD

	enc_counter = 10000
	new_val = PORTC & %00000011
start:
	old_val = new_val
again:
	new_val = PORTC & %00000011
	
	IF new_val = old_val Then again

	direction_bit = old_val.bit0 ^ new_val.bit1
	
	IF direction_bit = 1 Then  
	
		LCDOut $fe,1,"Last was CW"
		enc_counter = enc_counter + 1
		LCDOut $fe,$c0,DEC enc_counter

	else
		LCDOut $fe,1,"Last was CCW"
		enc_counter = enc_counter - 1
		LCDOut $fe,$c0,DEC enc_counter	
	
	endif

	GoTo start

[RodSTAR]

File attachment = Incremental quadrature encoder direction drawing.

Luciano

Luciano: five stars!