Sunday, April 3, 2022
HomeIoTThis Tiny OLED Display screen Is Managed with an HDMI Cable

This Tiny OLED Display screen Is Managed with an HDMI Cable

A easy concept

For prolific maker Tim Alex Jacobs, who goes by mitxela, his tasks are pushed by the query “Is it attainable?” slightly than “Is it sensible?,” and his newest venture splendidly demonstrates this idea. After toying round with the thought of utilizing an HDMI connector for one thing, Jacobs realized that it incorporates a pair of conductors that comprise an I2C bus, and this could possibly be repurposed and mixed with a small OLED display that will turn out to be a really small monitor.

The HDMI specification

An HDMI connector has 19 pins in whole, with practically all of them going to high-speed knowledge, clock, and defend traces that carry huge quantities of show data to the display on the different finish. Nevertheless, pins 15 and 16 are for an I2C connection between the host and peripheral controllers, as they typically have to share setup data or modify a setting.


With this new information in thoughts, Jacobs set to work by first stripping off one finish of an HDMI cable and finding the pins for serial knowledge, serial clock, 5V energy, floor, and the new plug detect pin which alerts to the host {that a} show has been connected by pulling its sign excessive. Even higher, the 5V line is ready to supply as much as 50mA of present, which means that the OLED wouldn’t need to depend on an exterior energy provide.

Controlling the display

Utilizing linux on a laptop computer, Jacobs ran a number of I2C-related instructions that allowed him to view all the connected I2C buses and the gadgets on them. As soon as the OLED on the HDMI show knowledge channel (DDC) was discovered, a fast take a look at script was run that makes use of smbus through Python to ship an allow command adopted by some textual content that ensures the show is functioning appropriately.

Making a monitor

After making all of those modifications, the ultimate step was getting the tiny 128×64 OLED show to behave as if it was an precise monitor linked to the laptop computer, full with a mouse cursor. Writing a video driver from scratch would have taken an enormous period of time, so as an alternative, Jacobs opted so as to add a dummy monitor through the xrandr utility so as to make the xorg show server suppose an precise monitor is connected. Lastly, a Python script was added that makes use of the python-xlib package deal to seize the framebuffer from the digital monitor, overlay a mouse cursor, and ship it to the OLED over I2C.

Though the framerate may use some enhancements, it’s fairly enjoyable to observe one of many worst HDMI shows ever created act as a full-fledged monitor and even present a fundamental terminal with it. For extra data, you may examine this venture right here in Jacobs’ weblog put up or watch his video under.



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