September 18th, 2021—
For many makers, it’s always fun to take some piece of old technology and give it a new lease on life, especially when the item in question was destined for the landfill. This is what prompted Alastair Aitchison — better known on YouTube as Playful Technology — to grab a deprecated vacuum fluorescent display (VFD) module from an Epson point-of-sale device and interface it with an Arduino Nano as a real-time display.
VFDs can be thought of as character LCDs, but rather than having many dot-matrix units that use the alignments of suspended crystals to block light, tiny phosphor crystals light up when a current is applied. The module isn’t driven directly by the Arduino Nano since it requires a far higher voltage so a special display controller chip is integrated, which receives commands/data over an RS-232 port and manipulates the onscreen graphics accordingly. This meant a MAX232 had to be used to convert the Nano’s 5V TTL voltage into the -15V to 15 range.
The programming for the Epson VFD unit was quite straightforward due to Epson’s great documentation, so knowing what data to send and when was a breeze. The code starts by initializing the display module and gives some example text. It finally enters a loop that reads data from the serial port and sends it over UART to be shown. To see all of this in action, you can view Aitchison’s video below.