Warning message

The Propeller Object Exchange system is decommissioned and replaced with a GitHub repository to house the same existing and future Propeller objects. As of 12/5/2019, this site is read-only. You can continue to browse and download objects from here for a limited time; however, please begin using the Parallax Propeller repository for future reference.
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0
Request group membership
Auxiliary Files
By: created: 2014-07-02 | updated: 2014-07-02
This object uses the Interrupt-On-Change feature of the Microchip MCP23008 I/O Expander chip to interface a 4x4 Matrix Keypad (Parallax #27899) to a propeller MCU.
When a key on the keypad is pressed, the MCP23008 goes LOW and the propeller scans the rows and columns to determine which key is pressed.
Then it clears the interrupt as the key is released.
See Microchip's Application Note: AN1081


Original File Upload
Package icon I2CKeypad.zip19.47 KB
Image icon MCP23008 board.jpg90.04 KB