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Repurposing the VFD unit from an old Epson POS display using Arduino

Arduino TeamSeptember 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.