EDTP Packet Whacker / EECS - Chipselect usage ?

[Izolator]

Hi guys :-)
Hope you can help me out with a simple Chipselect question.

I'm doing my Finals with a project:
Pic16F877
Packet whacker - www.edtp.com
HD44780 LCD - 2*16, scrollable

What I am doing:
I am out of datapins on the pick with the basic setup of the Pic and the Whacker. I figured I could use PORTD as a shared databus between the LCD and the Whacker, cool.

Problem:
I need to make sure that the Whacker does NOT recieve the data sent to the LCD. The LCD has a CS option (e.g. pin6 Enable= '1').
The Whacker however does not have an apparent CS option.
I did notice that 1 pin on the whacker is not used/connected. EDTP calls it EECS.

My question:
Has anyone got experience with this combo or at least enough diagram knowledge to tell me whether or not I could use the EECS to deselect the Whacker and thus make sure that the Whacker does not use/read the databus while I am adressing the LCD.

My fear is that the EECS is only for the eeprom part of the whacker, not the entire kit.


Hope someone smarter than me can crack this one :-)

Reference:
http://www.edtp.com/download/pw/whacky.exe


Thanks, always a pleasure reading this forum.

BR
Rasmus 'Izolator'

[rwyoung]

Here are some suggestions. Since this is for your schoolwork (and congratulations on saying that up-front, most people don't) these are a little vague but should stimulate the creative process...

0) Look at CCS LCD example code to see how they mapped the LCD to port B. Would also work for mapping to port D
1) Use 4-bit interface for LCD instead of 8-bit wide version. Saves 4 I/O lines.
2) Use 3 lines to control LCD by putting shift register (eg 74hc164 or 74hc595) between PIC and LCD. Again use LCD in its 4-bit interface mode. However this does not let you read-back from the LCD although most people don't do that anyway.
3) Use bus transceivers like 74hc245, 240, 241, 244, etc and selector/decoder like 74hc138 or 139 to make data bus. Then everybody gets to ride the bus.
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month!

[Izolator]

mmm mmm...

That was exactly what I was hoping for
I think I will go for a solution with external IC's for sharing the bus.

Thankyou so much


BR
Rasmus 'Izolator'