Need help optimizing an LED design controlled by rotary switch

Question

Hello all I have a very specific project I am working on and while I have a working prototype I feel that there are things I can do to further optimize the design.

What it is

This is a simple feedback system for people to rate content they are watching live on a scale from -3-0-+3. The system consists of seven LEDs three red, followed by one blue and three green. These are controlled via a seven position rotary switch. I currently have this all plugged into gpio pins on an arduino mega and I would like to reduce the number of pins I am using. The reason I am using so many pins is I need to be able to light the leds sequentially i.e. three red, two red, one red, blue always on, one green, two green, three green. Meanwhile the Arduino program outputs the current selection over the serial port to a program that records this output.

What i want to do

Basically I want to reduce my pincount using Charlieplexing or some sort of led driver. I am currently using up 14 pins on the Arduino and I want to incorporate some other functions into this system. I am thinking charlieplexing is the answer but if there is a better solution I am open to suggestions!

Thanks in advance!

dougw · Accepted Answer

You could use the rotary switch with 7 resistors feeding a single analog input to indicate to the arduino which state is selected. Then you could de-multiplex 3 outputs from the arduino to implement the desired LED state.

Robert Peter Oakes · Answer

Perhaps use a rotary encoder with the assumption you can overshoot your desired reading as the pot turns continuously, this will only use 3 pins per rotary encoder and the software can take care of over run use WS2812B LEDS as these are serially connected and require only a single data line to control thousands if needed and only cost about 20-30c each on ebay and the like Oh, and then they can be any colour you like too Peter

Former Member · Answer

One great product is the attiny 85 with a the rotary charlieplex you can do everything you need as long as its less than 6 pins. The attiny uses arduino software and can be programmed with a few jumpers and an arduino.