What is it?

The HPDL-1414 is a smart, four character, sixteen-segment, red GaAsP display, offering a retro-style alphanumeric screen. It is capable of displaying both numbers and a limited set of characters. With its bright and clear LED technology, it offers excellent visibility in different lighting conditions, making it suitable for indoor and outdoor applications. The monolithic LED characters are magnified by an immersion lens which increases both character size and luminous intensity. This display is perfect for retro smart watches, clocks and control panels. See video below for a demo.

The HPDL-1414 display typically requires 10 GPIO pins for operation. However, with this breakout board, I have combined it with an ATMEGA328p microcontroller and made modifications so that it can now be controlled using just one GPIO pin through a Serial UART TX connection. This greatly simplifies driving it.

To use it, you need to connect VDD (it has an onboard 3.3V voltage regulator) and GND, and then connect the TX pin of your microcontroller to the RX pin of the breakout board. You can leverage the standard Arduino Serial library at a baud rate of 9600. To change the characters displayed on the HPDL-1414, simply use serial print lines like Serial.println("TEST"), and the text will automatically appear on the display.