Brian Harris wrote :

> I'm using a 18F452 to read a HCTL 2016 
quadrature decoder. 
> I can read the output bytes anytime before 
overflow with:
> 
>   bcf  OE           ;enable tristate output
>   
bcf  SEL          ;for high byte
>   nop
>   movf portb,w     ;data 
from HTCL 2016 received on portb
>   movwf d_hi       ;store
>   bsf  
SEL          ;for low byte
>   nop
>   movf portb,w     ;data from HTCL 
2016 received on portb
>   movwf d_low     ;store
>    bsf  
OE            ;disable tristate output
> 


Just a tought and might not 
apply
to your actual problem... :-)

Is there something in the encoder 
that
makes sure that there isn't a change
in high/low byte betwen the 
two reads ?
Much like when reading TMR1H/L regs (for
which there is a 
fix in the PIC hardware).

>   bcf  RST          ;to reset counter
>   
nop
>   nop
>   bsf  RST

What happens if the encoded moves
between the 
bcf/bsf ? Does it still
"count" internaly in some way ?

Jan-Erik.



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