Electrical Engineering

Questions tagged [charlieplexing]

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Charlieplexing is a multiplexing technique allowing to control N \$\times\$ (N-1) LEDs or buttons with N I/Os.

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How can I use Charlieplexing with common anode RGB LEDs?

I've an ESP32-based dev board (LoLin32) which has 26 digital I/O pins. I want to connect 25 common anode RGB LEDs to it. Connecting them in the 'normal' way would require 75 I/O pins, which I don't ...
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2answers
210 views

Charlieplexing ledstrips together

I know there is a lot of charlieplexing tutorials out there but non of them are very suitable for my case. I want to charlieplex 4 ledstrips together and control them by an arduino. This means that i ...
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0answers
511 views

Reading an LDR array with a Raspberry Pi

I am trying to repurpose a replica GPO 746 using a Raspberry Pi, however the rotary mechanism is rather different to that in an original 746. The circuit has 12 LDRs arranged in an array (3 columns, 4 ...
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2answers
989 views

200 LED through arduino via SN74HC595N shift register

I'm very new to any forms of multiplexing let alone electronics itself. From what I have researched, I can add more inputs/outputs to an Arduino via a shift register. I bought 10 SN74HC595N shift ...
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1answer
203 views

How to connect a large number of multi-throw switches efficiently?

I have a number of 7 pole single throw switches that I need to connect together in some sort of grid configuration to a microcontroller, while minimizing the number of pins on the micro and the number ...
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2answers
608 views

Charlieplexing 7-segment display segments vs segment

I understand the principle of charlieplex and the use of tri-state. What I don't understand is, can I light all segments on a display at once or do I have to light one segment at a time? Say I have 8 ...
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1answer
166 views

For 12X8 LED array with any 1 LED glowing at a time, should we charlieplex or use 74HC595n?

Apologies in advance for probably missing a lot of things. I'm pretty new to electronics. I'm building a 96(12X8) led (monochrome ultra bright, white) multiplexed array, driven by an Arduino nano. ...
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2answers
890 views

Arduino - Controlling 8 RGB LEDs (beginner question)

First time poster here. I have an Arduino Uno project that will require 8 RGB LEDs to be controlled. They will be turned on and off with pushbuttons, cycling through red, then green, then blue, then ...
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2answers
3k views

Is it possible to drive a 4x4 RGB common-cathode LED matrix with a MAX7219?

The MAX7219 (datasheet) is a LED matrix driver that's designed to drive an 8X8 single-colour LED array. tronixstuff has an intro on how to use it with an arduino that has some relevant diagrams. I'm ...
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1answer
491 views

How to debug a circuit that uses Charlieplexing and PWM with LEDs under ISIS?

Using mikroC and Proteus ISIS, I have built a circuit that uses a PIC12F629 (link to datasheet PDF). It controls several LEDs using Charlieplexing technique (and additionally PWM them to change their ...
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1answer
424 views

Need help understanding charlieplex circuit

I understand the principle behind charlieplexing, however I don't understand how the circuit below works. Say I wanted to illuminate LED5, wouldn't I set Pin1 to OUTPUT-LOW, Pin2 to INPUT, and Pin3 to ...
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1answer
2k views

Building a 3x3x3 LED cube?

I need to built a 3x3x3 LED cube. I need to be able to turn every LED on (not at the same time) in different patterns. I need to use Charlieplexing (note that any other method is not a viable option),...
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2answers
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7-segment LED display with multiple digits

I was looking at the datasheet for the LTC-4627JR, and it looks like each digit shares a common anode, and each segment shares a common cathode. My question is given this configuration, I don't ...
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7answers
32k views

How do I control several hundred individual leds with Arduino(s)?

I am working on an electronics project which involves hundreds of LEDs. (Talking upwards of six to seven hundred LEDs...a lot, I know.) Is there any way to control this many LEDs with one or a couple ...
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1answer
2k views

How to increase current drive of Charlieplexed LED array?

I am driving 15 LED's with a Charlieplexed circuit (using an Atmel ATTiny13). I've reached the current limit per I/O pin of 40mA and would like to drive the LED's higher (they're rated at 50mA). Is ...
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1answer
2k views

Chaining limit for shift registers in large led matrix

I am thinking of trying to build a large led matrix in a way that is both modular and scalable (maybe up to around 100x100, or 500x16). My thought is to make a single 8x8 module that I can make a few ...
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1answer
533 views

Charlieplexing different LEDs

I have four LEDS (Red,Green,Blue,Yellow) and want to use charlieplexing to light them up. I'll use an Attiny13V which needs 1.8 to 5.5V. I think one CR2032 with 3V will be suffice for the µC. The ...
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4answers
471 views

Charlieplexing Topology Question

I'm sitting here with a pencil and paper trying to arrange a charlieplexed 5x8 LED matrix. I'm trying to arrange this in such a manner that no two lines cross each other. Without a guiding theorem of ...
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2answers
6k views

Is Multiplexing ever superior to Charlieplexing?

I've reviewed the two methods, and multiplexing really only appears to have one advantage, that it would be easier to track down a failed LED than in a Charlieplex array. Can someone more ...
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3answers
1k views

CharliePlexing on a breadboard

I was making a breadboard demo for a Microcontroller class. Basically my project is to make a score keeping device. I want to drive 4 seven segment displays using an atmega8. I read about charlie ...