- Hello, PIC_World !


- I 'm thinking about how to make a minimised KeyBoarD interface to wire
with my PIC

- I 've two solutions :

  - A 3 wires version using 2 Output & 1 Input of the PIC & a external
IC, a CD4040 14-bit ripple counter &      some sheet around (pull-up,
transistor, etc...)

  - A 1 wire version using a ANALOGIC input of the PIC & some resistors
(R-2R net)

- In the 3 wires version, I could have how many key that I wish, but I
scan the KeyBoarD, key-after-key

  - 1 First I RESET the Counter(CD4040), keys are selected by Outputs of
the IC-Counter
  - 2 Then DATA line equal: 0=key_up  1=key_down
  - 3 For next key, I put a CLK pulse in the IC-Counter, and go to 2

  - RESET is an Output of PIC wired to IC-Counter (CD4040)
  - CLK is like RESET
  - DATA is an Input of PIC wired with all key_out

- In the 1 wire version, the Nbs of keys I want is less, but no
scanning, just an Input, and no other ICs

  - For each key I assigne a value :
     - key_1= R
     - key_2= 2R
     - key_3= 4R
     - key_4= 8R , etc ...


- I don't know if it's a good idea, may be 8 keys with 1 A/D Input(8
bits) ?

- And You ! What do You think about that ? Another(s) Idea(s) ? Hope you
reply .

:-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) (-: (-: (-: (-: (-:
(-: (-: (-: (-: (-: (-: (-: