One input keypad?


New Member
Thats a good point 'Perhaps if none of these strategies work, the alarm should go off'. As per my code right now, the default PIN is stored in EEPROM. The user types in their PIN, hits enter and is then given the choice to arm/disarm the system, cancel or change the PIN. If they choose change PIN, they're prompted to enter a new PIN then hit enter. The new PIN is then stored in the EEPROM over the old one.

Im looking more and more at the 'divider chain' setup. The code is so short and simple. I could cut down 37 lines of code to about 10.

Im gonna get some parts and another protoboard Monday and build one to do some testing. I will try with 100k(maybe 1M) resistors. I may test the feasibility of making one of the alarms battery powered with solar recharge. The circuit with 10K resistors draws a constant 29uA. Using the 100k resistors draws a constant 2.94uA(1M draws .29uA). Regardless, Ill test it out, prove the mathcode works and possibly convert to it for my alarm. I certainly appreciate all you and everyone else who contributed input and opinions. More heads always make for a better product.

Edited by - Jon Henry on 12/08/2007 16:09:58

Edited by - Jon Henry on 12/08/2007 16:13:20


Senior Member
This is great work on the keypad. I am adding this post because of a product I just saw from a parallex distributer. It is a serial keypad. So maybe that is also worth a look ? I guess that would also be a one input keypad?


Senior Member
Serial Keypad(chip) and Serial LCD chip.
35 Woolart street
Strathmore Victoria 3041 Australia
Fax (61-3) 9338-4596


Senior Member
Thanks for the Info.

This appears to be a dedicated 18 pin PIC chip programmed as an interface to decode a standard matrix keypad. This is something that could also be done with a PICAXE.

The 'One input keypad', or the later 'ADC keypad' requires only resisitors and an ADC input. Refer to the spreadsheet on JonHenry's website for discussion & calculators for both Matrix and separate key keypads.


Edited by - BCJKiwi on 03/09/2007 10:39:28

Am unable to add the spreadsheet to this post - I guess it's too old??
Please see post #10 in finished projects/miscellaneous/ADC or 'one input' Keypad Decoder for the latest version of the spreadsheet.
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