Matrix keypad
16 keys - 8 bits - keypad
Fig. 1 keypad with adapter
Description:
This board allows the connection of a 12 or 16 keys keypad to an 8 bits port.
The keypad is organised as 4 rows of 3 or 4 keys.
The board can be powered by 1.8 to 5V processor board.
Specifications:
Input voltage2.5 to 5V
Keypad type12 or 16 keys
Interface8 bits
Schematic:
The schematic is very simple. R1 to R4 pull high the columns. It is needed if connected to open drain pins. Bit 0 to 3 are connected to the rows of the keypad, and bit 4 to 6 or 7 to the columns (12 keys have 3 columns, 16 keys 4).
K1 connects the keypad to an 8 bits bus, K2 connects the keypad itself.
Fig. 2 keypad schematic
Construction:
The PCB fits on a small single sided board. All components are on the top side. K2 is a female header. The keypad is fitted with a male header, so it can easily fit on the adapter.
Fig. 3 keypad layout
Once all the components are soldered, the board is ready.
| Keypad Component list |
|---|
| R1, R2, R3, R4: 100 K K1: Connector AMP MT 10pins male K2: Header 2.54mm 8 pins female KP1: 12 or 16 way keypad with matrix output |
How to use / Testing:
To check the board, you need a processor board running tutorial 12 - keypad.
Files and links:
Eagle PCB and schematics files for keypad.PDFs of PCB, layout and schematics of keypad.
PIC Tutorials 12 with keypad.