- Parallax P2 Eval LED Matrix Add-On Board
- Equipped with 56 Charlieplexed green LEDs
- Requires only 8 I/O pins for full LED control
- Features a pass-through socket for easy stacking
- Assembled and tested in Rocklin, California
The Parallax P2 Eval LED Matrix Add-On Board is equipped with an 8 x 7 grid of Charlieplexed green LEDs. This board is designed to be used with Propeller 2 multicore microcontroller projects, enabling the display of text or graphics across 56 LEDs using a mere 8 I/O pins. The board utilizes Charlieplexing, a technique that controls a larger number of LEDs with fewer I/O pins. This is achieved by leveraging the one-way current flow properties of diodes, including Light Emitting Diodes, in conjunction with the tri-state properties of the Propeller 2 I/O pins.
The board does not light multiple LEDs simultaneously but rather switches them on and off rapidly enough to create the illusion of simultaneous illumination to the human eye. This is achieved when the Propeller 2 code switches each LED on and off at least 50 times per second (50 Hz), resulting in a flicker-free appearance and the illusion of the LEDs being permanently on. The Propeller 2 is capable of switching at speeds faster than 180 MHz, providing ample time to activate every LED if necessary.
The Parallax P2 Eval LED Matrix Add-On Board also includes a pass-through socket that stacks on top of a 2x6 accessory header on the Propeller 2 Evaluation Board. Additionally, it is compatible with a P2 Edge Module Breadboard or a P2 Edge Mini Breakout Board with a P2 Edge Module installed.
