On Sep 1, 2005, at 9:07 AM, Augusto Yipmantin wrote:

> The original program was working well in a pic16f84a, but when I change
> the headers and compile it for a pic16f628 never works.
>
The 628 has peripherals not present on the 84a that share the IO pins,
and must be turned off in order to use those pins and normal digitial
IO.  The usual problem is the analog comparator module (unfortunately
it makes a lot of sense that pins that might be connected to analog
voltages power up in analog mode!), and you need to insert 
initialization
code like:

    CLRF PORTA  ;Initialize PORTA by
                ;setting
                ;output data latches
    MOVLW 0x07  ;Turn comparators off and
    MOVWF CMCON ;enable pins for I/O  ;functions

(This from "example 5-1" of the 628a datasheet.)

BillW
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