Johannes' Blog

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).

I have been asked for a schematic of my C64 power supply a couple of times. So here it is.



The correct value for the transformer's primary rating depends on your mains voltage, of course.

For a detailed description of my circuit, please have a look at the original article.

Since the wide availability of blue LEDs, manufacturers of electronics devices tend to use blue LEDs as power indicators. They especially seem to like those extra-bright blue LEDs.



I, on the contrary, find them pretty annoying. Am I alone here? Do people actually like them?

Recently, I have been asked by Farnell if I were interested in taking part in their free product road test program. As I like tinkering with electronics stuff, I said yes and chose the STM32F4-Discovery board as an item to test.



The STM32F4-Discovery board is little development/evaluation board from ST to promote their STM32F4 micro controller series. The STM32F407 on the Discovery board consists of a 32 bit Corex-M4F ARM processor (which can run at up to 168 MHz), 192 kB of RAM (112+16+64 kB), 1 MB of flash memory and lots of peripherals (timers, DMA controllers, DACs, ADCs, two USB OTG ports, ...) and of course lots of general purpose I/O pins.