Mark Crankshaw wrote:

> I'm still quite new to PICs (and have just returned to the list after a
> break) but have used 'F84s successfully for a couple of projects. Now that
> I can obtain 'F877s I am trying to convert my projects to use the 'F877 so
> that I can then expand the projects.
>
> However I'm having problems. I started by simply changing register
> addresses to suit the 'F877 but that didn't work. To cut a long story
> short I'm now back to trying to get LEDs to flash! I have a simple circuit
> on stripboard with an 'F877, voltage reg.,0.1 uF cap. across the supply, 4
> MHz crystal with 2 15 pF caps., MCLR tied directly to 5V and 8 LEDs with
> resistors on PORTB. The following program works, well kind of - the
> LEDs come on one at a time and then go off rather one running up and
> down the line, but at least it does something (WDT enabled of course):
>

Mark, you can use include files to set the values for each PIC special
function register:
example:
 #INCLUDE        <P12C671.INC>
(*.inc files will be hild in your MPLAB directory)

you can set config registers like this:
 __CONFIG _MCLRE_OFF & _WDT_OFF & _INTRC_OSC_NOCLKOUT & _PWRTE_ON & _CP_ON

free ram file registers can be set in bulk like this:
    CBLOCK  H'20'        ;(substitute free ram start value for your processor)

        INT_W,INT_STATUS,INT_FSR
        TRX_PTR,XBITPOS
(etc)
    ENDC

Check the initialisation values for special function registers, ports may be
set for analogue input etc.

regards,
Graham.