Johannes' Blog

The Gmu source code is now available on Github. There are also a couple of previously unreleased features and a new branch of Gmu that supports the more modern SDL2 (instead of SDL1.2).

If you want to build Gmu yourself, go check it out.

While the CH341A Mini Programmer is a very versatile device - not only can it be used as an SPI flash programmer, but also as a UART and possibly even an AVR programmer, it is known to have a design flaw, probably due to a misinterpretation of the fairly vague CH341A datasheet by the people who have designed the Mini Programmer.

I have designed a 3D printable case for the Hardkernel Odroid-H2 single board computer (SBC) with OpenSCAD. The H2 is an x86-based board with an Intel Celeron J4105, two DDR4 SO-DIMM slots and lots of I/O (2x GbE, 2x SATA, M.2 SSD, USB3, DisplayPort, HDMI, ...).

The case is configurable and supports up to one 2.5" disk drive with a height of up to 15 mm. It consists of two parts and is pretty easy to print.

I've got one of these simple remote controlled RGB LED strips. Using the IR remote control that came with it to select colors is fine, but I wanted to be able to control it through a computer. That way it would be possible to do things like turning it off when playing a movie for instance, or using it to signal any kind of event.



There are different options on how to achieve that. I could have replaced the whole LED controller circuitry with my own, but I didn't want to do that. What I decided to do instead is create a small circuit that emits IR signals that the original controller understands. That way I can still use the original remote control and do not have to modify any of the original LED strip components. The downside to this is that I am stuck with the capabilities of the original controller, which are rather limited.

I have finally come around to install Coreboot on my X220 laptop. It is an X220 with a Core i5-2520M and 16 GB of DDR3-1600 RAM.

Coreboot is an open source replacement for the BIOS/UEFI firmware of a variety of laptops and mainboards. Coreboot needs to be combined with a payload component, since Coreboot itself doesn't do a whole lot besides hardware initialization. The payload I am using here is SeaBIOS, which implements the features of a PC BIOS.



It allows you to boot most PC operating systems, including those that rely on the classic PC BIOS features. For UEFI support there is the TianoCore payload. It is also possible to use the GRUB bootloader as a payload or embed a Linux kernel as a payload (if the flash chip is large enough).