Introduction

Sometimes, it’s nice to use a luxury display such as a VFD! This short blog post describes how to get a 12-character alphanumeric display functioning with an Arduino. It's a straightforward task - just six wires to connect!

Exploring the Display

I used this particular display; others may work too, but I don't know!:

The display has six connections on the right side.

The underside of the board has not much, mainly a couple of voltage regulator integrated circuits (ICs). I don’t know what the part codes are, but connecting up a 5V supply and probing with a multimeter reveals that the left regulator provides approximately 27.8V output, and the right one generates a 3.3V output.

The in-built controller chip is part code PT6302, which I only learned through guesswork! The AliExpress product page had zero information about the display.

Connecting It Up

I’m not 100% sure, but I'm 95% sure the display requires 3.3V logic levels if I assume that the 3.3V regulator is providing the logic supply for the PT6302 chip, which is inaccessible to probe directly. Therefore, a 5V-logic Arduino (such as Arduino Uno R3) would require logic-level conversion.

I used an Arduino R4 Minima, which normally requires 5V logic levels but was modified for 3.3V capability:  Modifying the Arduino Uno R4: Making it 3.3V-Friendly 

There are plenty of 3.3V logic Arduino boards that could be used instead if desired, of course.

Just four digital pins are needed. The connections I used are below.

Arduino Code

Download the Vfd12 zip file library (it is based on code I found here. I turned that code into a library and tweaked it a bit to suit the particular VFD that I was using).

In the Arduino environment, click on Sketch -> Include Library -> Add .ZIP Library and select the zip file.

Click on File -> Examples and then near the bottom of the list, you'll see Vfd12 12-character VFD Library. Click on that and select VfdTest

Example code will be displayed. Connect to your Arduino and click on the Upload button!

It should immediately display a “Hello World” message.

The code is easy to use, and mainly just a vfd.print command will be used, for instance:

vfd.print(0, “Hello There!”);

The first parameter is the start position (0-11), and the second is the text string to display.

The code is easy to modify, but if you have problems, please leave a comment below.

What Characters are Supported?

All English characters and numbers can be displayed, i.e. alphanumeric, along with various punctuation. It is possible to user-define up to eight custom characters/symbols. The definition consists of five bytes for each custom character.

The example code demonstrates how to do that in an array. I've created some commonly-used symbols, such as degrees, left- and right-pointing triangles, and so on. The ones I created are:

0: right-pointing triangle

1: left-pointing triangle

2: pause symbol

3: overscore

4: degree symbol

5: u (micro) symbol

6: ohm symbol

7: phi character

To display a custom character, the vfd.printchar command could be used, for instance, to show a degree symbol at the seventh position on the display:

vfd.printchar(6, 4);

Summary

It was a pleasant surprise that it was so easy to use a VFD. I’d never tried this before.

The display is very clear to read and supports a decent character set with the capability to have custom symbols too. Just six wires are needed to use the display with any 3.3V logic-level Arduino board. A 5V supply is needed to power the display, however. When displaying a typical message, the current consumption of the display is about 70mA at 5V. I did not measure the current with all pixels illuminated.

All code is on GitHub. Direct link to the library.

Thanks for reading!

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