[hoonsa]

Hi I need to make a control access unit with a PIC18F452.

I've Connected a 5V Regulated wall outlet, Timer, Reset Switch (to program the PIC) and a RS232 & MAX232 Chip for PC connection.


I've researched on the other parts i need and just want to know if im heading in the right direction:

*3x4 Keypad

http://www.altronics.com.au/index.asp?area=item&id=S5381

R1 – pin3 C1 – pin4

R2 – pin8 C2 – pin2

R3 – pin7 C3 – pin6

R4 – pin5

I found a MM74C922 4x4 Encoder I.C.

http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=1013909

There are 4 pins on this chip I’m unsure whether this is what im spose to do:

PIN5 – Oscillator (Connect 1u Cap then GND)
PIN6 – Keybounce Mask (10u Cap then GND)

PIN13 – OUTPUT ENABLE

(I saw 2 method to do this:

1. Connect PIN12 to a 74C922NOTGATE and follow it into PIN13 i.e PIN13 is the NOT of PIN12

2. Connect straight to Ground)
PIN12 - DATA AVAIL (This just shows that it goes directly to PIC I guess)<<i dont understand why we need this if we already have DATAOUT A,B,C pins going straight to the PIC???

Also Would i need a 10k Res inbetween the DATAOUT A,B,C and the PIC ?

[Ian]

I think this sort of question will be a bit out of the scope of the forums, as this is primarily for PC support. It may be better to ask somewhere that specialises in electronics, like :

http://www.dutchforce.com/~eforum/index.php

Good luck with the keypad