Mailbag: ePaper Display Module

Look what I’ve got by post today from our Chinese comrades at ‘Good Display’ factory: a nice small 2.04-inch electrophoretic display (EPD), or better known as ePaper/eInk display or ’electronic paper’.

[caption id=“attachment_232” align=“alignnone” width=“856”] ePaper EPD display front side view[/caption]

[caption id=“attachment_231” align=“aligncenter” width=“632”] ePaper EPD display back side[/caption]

Electrophoretic displays (EPD) do not require any power to retain  an image. Power is needed only when redrawing the screen. The technology is thus used in electronic paper readers such as Amazon Kindle or the Pebble smartwatch (correction: Pebble uses different display: Memory LCD).

The unit I’ve got is 2.04" display designed for use as electronic price tag at shelves in shops. The resolution is 172x72 pixels. It has 2-bit ‘colour’ depth, which corresponds to 4 grades of shade. The model number is GDE021A1.

If I read the datasheet correctly, the display requires DC-DC converter circuit to supply relatively high voltage 40V for refresh. Luckily the DC-DC controller is integrated, but a power MOSFET, a coil, and diodes must be connected externally over the connector. All other communication with the display is via SPI-like interface, so it should be quite easy.

I will get back once I have it working somehow. What is my target application? Well, I always loved Falout’s Pip-Boy (Personal Information Processor) device, but-you know-wearing a CRT on your wrist is not entirely practical (maybe unless there are mutant scorpions around).

UPDATE 2014-04-28: Below you can find a driver circuit for interfacing to an MCU. It is redrawn from the datasheet.

[caption id=“attachment_250” align=“aligncenter” width=“1354”] Basic EPD driver circuit, redrawn from datasheet[/caption]

 Tutorial video by the manufacturer:

https://www.youtube.com/watch?v=JUQKQ4mF4AY