RE: [CAD_CAM_EDM_DRO] Re: PIC DRO

I haven't measured the length of the ISR. Next time I work on the code I'll
take a look though. My emulator has a timing
option so I can easily find out. I know it's way under 1MS though. I'm
running at 20mhz also.

I started with Pics on 16C5X's. But have been using mostly 16C74's then 77's
and now F877's for the last couple of years.

later,
Larry E.

-----Original Message-----
From: Matt Shaver [mailto:mshaver@...]
Sent: Wednesday, April 05, 2000 9:11 PM
To: CAD_CAM_EDM_DRO@egroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: PIC DRO

> From: Larry Edington <larrye@...>
> It is true that even with the F877, the databook says you shouldn't
> poll the port if you are using the interrupt on change feature.
> So, I use the upper nibble for the two encoders, I use the INT0 pin
> ( RB0 ) for a different external interrupt, and the other 3 pins for

outputs

> so there's no polling necessary of the port. ( well other than in the

ISR

> to look at the encoder's value )

How long is your ISR (timewise)? You're lucky to have an onboard hardware
USART for the serial interface! My own PIC experience is solely with the
C5x
series and I've done quite a lot with software UARTs.

Matt


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