Wireless LED Scoreboard
Overview
This project is an LED scoreboard that can be controlled using IR remotes. It consists of a central control unit onto which up to four display faces can be attached, and remotes that are used to update the display.
Control Unit
The scoreboard is controlled by a Raspberry Pi Pico. The control unit has a 26-pin header on each of its four edges, allowing up to four displays to be connected. The four displays are identical, and have the same output. The control unit provides 3.3V power to the displays, as well as directly controlling two 4-digit 7-segment LED displays, and indirectly controlling two 10-segment bar LEDs. It also receives signals from the IR detectors.
Display Face
The display face has two 4-digit 7-segment displays and two 10-digit bar LED displays. The 7-segment displays are driven directly by the control unit, with one pin for each of the seven segments on the left, and one each for the right display. The control unit cycles through enabling each of the four common cathodes, relying on persistance of vision to display the full number. Controlling the numeric display takes 18 pins. The bar LEDs are controlled by a decade counter. The decade counters only output one of their pins high at a time, and have a reset pin and a clock pin. On triggering the reset, they output zero, and on each clock rising edge the output increments by one, looping from nine to zero. This gives 10 of the eleven states for the bar LED, and the eleventh is obtained by holding the clock signal high. The bar display takes 3 pins. There is a 3.3V and GND pin, and a pin to send the output of the IR detector to the controller, for 24 total pins. This leaves 2 pins for potential future expansion.
Remote Control
The remote is powered by 2 AA batteries, and communicates with the scoreboard using an infrared emitter. There is a decade counter that is being cycled through at 1kHz. The output of the decade counter goes to the IR beacon in such a way that each button corresponds to a unique 10 bit sequence being emitted. The first five bits are always the same - so that the control unit can lock on to the beginning of the signal. There are 5 buttons, with 2 DIP-switches, for 20 possible outputs. The buttons may have to be pressed for up to 19 clock cycles to send a complete signal, although the clock speed can be adjusted by changing the capacitance of C2.
