>
>Carey Fisher - NCS
>
>> If you always read from PORTx and always write to LATx, you
>won't get
>> bit by the Read-Modify-Write situation. Right?
>
>Well, yes, but note that some instructions
>both reads and write to the same FSR in the same
>instruction, like BCF/BSF. If you concider those
>as "write-only" instructions, then yes. :-)

>-----Original Message-----
>From: Jan-Erik Soderholm [mailto:jan-erik.soderholm@TELIA.COM]
>Sent: 12 March 2004 08:12
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [PIC:] My first program, 18F452, please critique
>
>
>And, you still might have the case of capacitive loading
>on (output) pins that makes the READ from PORTx reading
>the wrong state (that is, not what's in LATx). If you
>have this rece condition, you might still need the
>shadow register to hold a "copy" of your output status.

The only time I could imagine wanting to do this is perhaps in some kind of
safety critical code where you need to confirm the pin is actually set the
same as the ouput latch, in which case reading the port a suitable time
after setting the LATx register would be the only real way to achieve this.

Regards

Mike




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