Wednesday, May 8, 2019

Project Ideas using Seven Segment Displays

Documenting some ideas using multiplexed / charlieplexed seven segment displays. A seven segment display can have an LED in reverse polarity connected between each segment pin and the common pin.

A common anode and common cathode seven segment display can be placed in parallel, only one of them will be lit, reverse the polarity of the pins to illuminate the other one.

1) Enigma Machine:
 - Arduino Mega2560 R3 Pro Mini
 - (4) 16 segment displays, 17 pins to drive segments, 4 pins to multiplex digits
 - (26) LEDS for lampfield, shares 17 drive pins with main display, in reverse polarity
 - (26) pushbuttons for keyboard, 17 drive pins with 2 selection lines
 - (26) plugs for plugboard, 26 individual pins, one configured as an output and 25 scanned for jumper

2) Enigma Z30 Machine
 - Arduino Nano
 - (4) 7 segment displays
 - (10) LED for lampfield
 - (10) push buttons for keyboard
 - (8) push buttons to increment/decrement each wheel
 - (1) push button to enter configuration menu

3) 144 digit seven segment art installation.(12x12 matrix)
 - 9 tiles, each one has 16 displays (4x4 matrix)
 - each tile has 8 common anode seven segments display in parallel with 8 common cathode.

4) 34 digits of PI
 - Arduino Nano (18 I/O pins), not using (2) serial port and (2) analog input only pins
 - 34 charlieplexed seven segment displays using this technique:
 https://www.instructables.com/id/Charlieplexing-7-segment-displays/
 - 17 common anode charlieplexed displays + 17 common cathode charlieplexed displays

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