9

You could use a cheap and readily found 74HC595 (or similar) shift register to easily control hundreds of LEDs using just a few pins from the arduino. Theres even a a tutorial on this on the Arduino site! Serial to Parallel Shifting-Out with a 74HC595 Shifting Out & the 595 chip At sometime or another you may run out of pins on your Arduino ...


9

When you multiplex a large number of LEDs individually the common way is to use an N x M matrix. The time is divided in N steps, in each step you activate one of the N row lines, and the column lines that correspond of the LEDs you want to enable. Note that the row lines can each carry M times the LED current, which asks for some buffering. Each LED is on ...


7

Actually this is a very common arrangement. Each digit has its anodes connected together, and the segments for all digits have their cathodes connected. The controller enables one of the common anodes, drives the segments, and waits, then turns off the cathodes and moves on to the next common anode. This arrangement and control method is called multiplexing, ...


5

You say you did this successfully with 27 LEDs all in "one layer". As starblue said in a comment, 27 LEDs is 27 LEDs, regardless of how they are arranged mechanically. As a thought experiment, imagine the same 27 LEDs you already have working in one layer arranged in a line. Now fold them up to be a rectangle of 3 x 9 LEDs. Now imagine each group of 3 x ...


4

You can't use Charlieplexing with common anode, nor common cathode. You need to have the anodes/cathodes across every pin. A relatively simple solution in your case would be to acquire a couple of shift registers, the 74HC595 gives you 8 extra outputs at the cost of three pins on the ESP32. You can daisy chain the 74HC595 and have 16 extra outputs and ...


3

The answer is no. If the matrix has 4 cathodes and 4*3=12 anodes, and the driver has 8 current-sourcing pins, it is not possible. If the LEDs' pins were individually accessible, you could rearrange them to 8 cathodes and 6 anodes which would work, like this: But still, there would be a problem with different perceived intensity for different colours. ...


3

Charlieplexing is fun, I do it too much. Usually the advantage of fewer lines costs too much in restricted facility, and the need to three-state the outputs rather than just drive them high and low. You can light one digit at a time, which is the same as you can do with normal 15 line multiplexing. Anybody that tells you only a single segment at a time ...


3

Turns out the answer was on the wikipedia page. Current will still flow across alternate paths (an alternate 2-LED path exists for every pair of pins in the 3-pin diagram, for example), but the reduced voltage drop across those LEDs in multi-LED paths will not be enough that they actually significantly illuminate. So, the other two LEDs are lit, just ...


3

This technique is called multiplexing. This allows more segments to be controlled using less number of I/O pins. To read more about multiplexing display read this article Using a high speed micro-controller it is very easy to multiplex segment displays in software. You have to ensure that your micro-controller & software run faster than the scanning ...


3

You need an external tri-state buffer to support increased source and sink drive while maintaining the necessary high-Z state required for Charlieplexing. This forum post discusses a few options. Several posts suggest a tri-state amplifier with a single microcontroller pin using a circuit similar to the following: By biasing the pin at Vcc/2, a tri-state ...


2

A bit of a late answer to this question, but here are 528 LEDs Charlieplexed off a single PICAXE 40X2. It would go up to 930 LEDs if all pins were dedicated to the job. The build : http://www.picaxeforum.co.uk/entry.php?25-The-PICaxe-orrery A video: http://www.youtube.com/watch?v=82LvqiaH-iA The PICAXE architecture is quite slow, so the maximum number of ...


2

I would build this in a modular manner. Maxim's 6960 will drive 64 LEDs for you, though it is a bit pricey. They are driven with a serial interface, and you can connect up to 256 of them together. The 7218/7221 would also work.


2

With Charlieplexing you only turn a single segment on at a time. You will quickly see that it's pretty much useless for a configuration such as yours because the duty cycle is so low (1/64) that it will not be visible in normal lighting. Conventional multiplexing will allow you to get a 1/8 duty cycle which is about as far as I would recommend pushing it....


1

*Figure 1. A 6-pin LED allows access to each LED's individual anode and cathode. Source: LEDs with more than two pins. No. Charlieplexing would be possible with 6-pin RGB LEDs but not with a common anode or cathode. simulate this circuit – Schematic created using CircuitLab Figure 2. An RGB charlieplexing scheme would need access to individual ...


1

You can't. Regular multiplexing using n column drivers and m * 3 row drivers (and m * 3 resistors if they're not constant current), where m and n are integers. So if you pick n = 5 and m = 5 you need 5 + 15 = 20 pins. The duty cycle would be 1/5 = 20%. So for 5mA average current you'll need 25mA row drive and 375mA column drive, which will also be the ...


1

simulate this circuit – Schematic created using CircuitLab Figure 1. Since accidental contact closure is not an issue the switch contacts can simply be wired in parallel for redundancy. Using this arrangement any multiplexed configuration including charlieplexing can be used. I don't think you can use less than one diode per switch except for switch ...


1

I love charlieplexing, perhaps too much. Do you mean 'any one' or 'only one' LED on at a time? With a 595 pin per LED, you can drive them continuously at high current, there is no reason why they should be dim. You can drive any combination of LEDs at full power. With charlieplexing, if done niavely, then the best duty cycle you get is 1:N when there are ...


1

The easiest way to control that many RGB LEDs is to use a strip of LEDs that already include their own controller, such as the WS2812B. In addition, there are libraries for many of the models of "addressable" LEDs already available. From there it's simply a matter of instantiating an object for the correct number of LEDs, setting them to the desired colors, ...


1

Proteus VSM (Virtual System Modeling) does not operate in real-time, at least not on even very high end desktop computers. The simulation is very processor-intensive, as you would notice if you brought up Windows Task Manager while the simulation is running. Depending on your computer's capabilities and the number of active simulation elements in your design,...


1

I am not sure if my answer is good or not...but why not speaking about WS2811 addressable leds stripes?? We want to do a LED matrix to show text. There is a project here (https://www.pjrc.com/teensy/td_libs_OctoWS2811.html), made on a Teensy, which is near same thing than an Arduino. I think it uses the concept of PWM (Pulse Width Modulation), and thus ...


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