On 22/09/2010 3:16 PM, Scott wrote:
>>   Up until now, I've only used the older (lower end?) PICs
> 16F and lower don't have LAT.

You might want to check that.  I'm using a 16F1934 and it does indeed=20
have LATx registers - 5 of them!

>> I think I understand the difference between PORTx and LATx, but in one
>> data sheet Microchip show port B being initialised like so:
>>
>> BANKSEL     PORTB
>> CLRF        PORTB
>> BANKSEL     LATB
>> CLRF        LATB
>> BANKSEL     ANSELB
>> CLRF        ANSELB
>> BANKSEL     TRISB
>> CLRF        TRISB
>>
>> Why bother clearing TRISB when you would be only writing to LATB anyway?
>> David...
> TRIS controls the direction of the pin (e.g. input or output).
> Use PORT when you want to read a digital input.
> Use LAT when you want to write a digital output.
>

Yes, I understand this.  But why bother clearing PORTx when clearing=20
LATx is really clearing the port?

Reading PORTx will give the actual pin level, but it seems redundant to=20
write to PORTx when LATx is available.

About the only reason to write to PORTx (when LATx is available) is=20
where you want the actual pin levels to be taken into account due to the=20
RMW operation.  I really can't think of a real application for this though.
David...

--=20
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David Duffy        Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717      Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au
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