Old and beyond help ?

[duncan303]

this is the one that rises in the west then flashes and rotates etc.

A very secular star that happens to belong to David then, have you envisaged it playing a little tune


____

[mackrackit]

Three pins are all you need.
http://www.picbasic.co.uk/forum/showthread.php?t=10200

Not the star of David though...

[DavidFMarks]

Hi
My secular star of David has 16 arms each with 8 hi-brite leds so the easy way (i think) is a matrix which requires 24 I/O pins. Whilst I could use some other Ports it would be nice the way I have set up the 44 pin demo board to use Port A. Two questions now arise:
1. Can I use RA6 and RA7 as outputs if there is a xtal connected across them ( do not know what the DC characteristics of a xtal are)
2. How the devil do I program the 16F887 so that those two pins are available as outputs. I understand that I have to set up the configuration word (register 1) so that bits 2 -0 are 100 which should set the two pins as available for I/O (subject to item 1 ((above)) But what is the syntax for doing this ? I see no rference in the Picbasic manual (or anywhere else) to this. I have looked at examples but cannot figure it out from that. Any advice on this would be appreciated
Cheers

[mackrackit]

1. Can I use RA6 and RA7 as outputs if there is a xtal connected across them ( do not know what the DC characteristics of a xtal are)

No , you will have to use the internal OSC.

2. How the devil do I program the 16F887 so that those two pins are available as outputs. I understand that I have to set up the configuration word (register 1) so that bits 2 -0 are 100 which should set the two pins as available for I/O (subject to item 1 ((above)) But what is the syntax for doing this ? I see no rference in the Picbasic manual (or anywhere else) to this. I have looked at examples but cannot figure it out from that. Any advice on this would be appreciated
Cheers

@__config _CONFIG1, _INTRC_OSC_NOCLKOUT & _WDT_ON & _MCLRE_OFF & _LVP_OFF & _CP_OFF

So you did not like the shift registers?

[DavidFMarks]

Hi,
I have set the oscillator to internat but since the crystal is already mounted on the 44 pin board I did not really want to remove it ! .. and yes I dis like the shift register idea but need more time to get my ancient brain around it and to obtain the chips ( Meanwhile Christmas lights are going up all round me !)

[mackrackit]

My board did not come with an external OSC mounted, I assumed yours did not also.

I thought you were asking if the chip was running off the XT could the pins be used as an output.

Is it Monday or something?

[DavidFMarks]

Sorry you are right, there is no crystal (it's my age) I still haven't figured out where the terms in your config expression come from. They are clearly assembler terms of some kind