The P2 Eval LED Matrix Add-on Board board features an 8 x 7 grid of Charlieplexed green LEDs. Your Propeller 2 multicore microcontroller projects may use this board to display text of graphics across 56 LEDs using only 8 I/O pins.
Charlieplexing allows for control of more LEDs with fewer I/O pins by taking advantage of the one-way current flow properties of diodes (including Light Emitting Diodes), along with the tri-state properties of the Propeller 2 I/O pins.
To light multiple LEDs, rely on the fast operating speed of the Propeller 2. While Charlieplexing doesn’t actually light the LEDs simultaneously, it switches them on and off fast enough to trick the human eye into believing they are on simultaneously.
When Propeller 2 code switches each LED on and off at least 50 times a second (50 Hz), flickering should not be noticeable and the LEDs will appear to be permanently on. (For the Propeller 2 this switching speed is no problem as each I/O could switch faster than 180 MHz, which is plenty of time to turn on every LED if needed).
This board features a pass-through socket that stacks on top of a 2×6 accessory header on the Propeller 2 Evaluation Board. It is also compatible with a P2 Edge Module Breadboard or P2 Edge Mini Breakout Board with a P2 Edge Module (#P2-EC) installed.P2 Eval LED Matrix Add-on Board Features:
- 56 LEDs in a 8×7 grid
- Only required 8 Propeller 2 I/O pins for full LED control
- Total current consumption 4 mA, thanks to Charlieplexing
- PCB Dimensions: 1.6 x 0.8 in (4.1 x 2 cm)