> >The last value written to PORT is in LAT. eg LATD holds the
> >contents that are to be written out if a pin is configured as an
> >output
>
> This is not quite correct. All writes to a port must by definition go
> to the data latch (LATx), even if you are actually writing to PORTx
> i.e. although you can read the pin states via PORTx you always
> change their state through LATx. The big problem comes from
> writing to PORTx, whereby the pins are read, the value modified
> and then written back to the data latch

Isn't that what I (hoped to have) said ? I tried to differentiate
between i/p and o/p and driving and reading

"The last value written to PORT is in LAT. eg LATD holds the
contents that are to be written out if a pin is configured as an
output"    <- here I was assuming an all-output port

"But, a read of PORT (which may be caused by a read-modify-
write instruction) over-writes what is in LAT. This can be trouble
if PORT is a mix of inputs and outputs, because PORT writes to
LAT"

That would have been better written without the parentheses. IOW
writing to PORT is a r-m-w action

We need a picture with some examples ;-)

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