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Keypad Demo for SBCMON SBC Hardware: Main | SBC Schematic/Parts List | Technical Details | All pages in PDF format
SBC In-System Programming: Information | VisISP-52 ISP Application
SBCMON Monitor/Operating System: Main Page | Manual
SBCMON-based Software: SBCMON Monitor | Keypad Demo | LCD Echo Demo | Hardware Clock | Software Clock
SBCMON-based PS/2 Software: PS/2 Comm Monitor | PS/2 Keyboard | PS/2 Mouse
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Download Keypad Demo for SBCMON

You may download either the source code or the ready-to-use Intel-Hex version of the keypad demonstration program. The Intel-Hex version may be loaded into SBCMON's memory using the L or Q commands. Download the source ASM program if you'd like to see the code that makes the keypad demo work.

Keypad Demo Program Source (keypad.asm)
Keypad Demo Intel HEX (keypad.hex)

NOTE: This demo program requires SBCMON monitor program to run. Be sure to download SBCMON first, install on your SBC, and then run this demo from within SBCMON itself. This program may require additional modification in order to run without SBCMON.

What Does this Program Do?

This is a 4x4 keypad demonstration program which will read keypresses on the keypad and echo them to the serial port where they may be viewed with the PC terminal program. The code includes simple debounce logic to filter phantom keypresses that would otherwise be observed due to the mechanical bounce of the key itself.

The routine will exit and return to SBCMON's main menu when the user presses any key in the PC terminal program.

Concepts Demonstrated by Program

This program demonstrates the following concepts:

1. Reading a 4x4 keypad.
2. Memory-mapped device & memory-mapped I/O.
3. Key debounce.
4. Code look-up table.
5. Delay based on instruction loops (1/20th of a second).