pic microcontroller discussion list <> wrote on Saturday, April 19, 2003
8:07 PM:

> Now...my understanding is that the only major difference between the
> 16F84 and the 16F628 is less ports, no UART, and no PWM.  Am I going
> to shoot myself in the foot trying to use the F84 for this?

The USART is a BIG time-saver, in development time and in the amount of
time you need to dedicate to bit-banging otherwise.

Probably the biggest other change between the 16f84 and '628 in your
application is that that the '628 has comparator inputs, and you need
to disable them to use the PORTA pins 'normally'.  I usually use
        movlw 0x15      ;
        movwf CMCON     ;

(The first line is from memory, check on the datasheet comparator section
to verify that is a setup for all digital I/O!)

You also need to check your __config settings, particularly MCLR enable and
the oscillator selection (the '628 has additional oscillator options,
including
a very useful internal 4MHz RC oscillator)

HTH,
Nigel

--
Nigel Orr, Design Engineer                 nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
               Tel:+44 1467 622332 Fax:+44 1467 625235
                   http://www.axoninstruments.co.uk

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