Category: Displays

Framebuffer Drawing with u8glib [VIDEO]

GDE021A1 is a graphics display with a resolution 172×72 pixels, each pixel is 2 bits deep (4 shades of grey). The display has an internal controller SSD1606 with a framebuffer. The framebuffer size is 172*72*2/8=3096 Bytes. When the display is powered up, the system processor sends initialization sequence that first sets up controller’s internal registers (the controller SSD1606 is fairly generic) and then sends new framebuffer content. The display controller then autonomously pushes the framebuffer contents to the physical screen.

The display controller can be configured to orient the framebuffer almost any way. I configured it into a landscape mode, with the X-axis going right and the Y-axis down, as shown on the photo.

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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’.

ePaper EPD display front side view
ePaper EPD display front side view
ePaper EPD display back side
ePaper EPD display back side

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 172×72 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.

EPD Driver Circuit
Basic EPD driver circuit, redrawn from datasheet

 Tutorial video by the manufacturer: