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Coreboot on the Lenovo Thinkpad X220

2016-12-30 11:00
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.

SeaBIOS payload

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).
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Schematic for the C64 power supply project

2016-04-06 16:13
I have been asked for a schematic of my C64 power supply a couple of times. So here it is.

C64 power supply

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.

A simple power indicator LED mod or: Why are super-bright blue LEDs so common in consumer electronics?

2012-10-15 17:29
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?
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STM32F4-Discovery board review

2012-07-04 22:25
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 the first 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.
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USB controlled SPÖKA night light

2012-03-12 10:28


This is an IKEA SPÖKA light. It is a small night light resembling a little ghost.


Originally powered by an internal rechargable battery, the light is controlled by a single button. When pressing that button it starts cycling through various color combintations. When you press that button again it freezes the current color. That's all it can do. Depending on the model the colors can be a combination of either blue and green or red, orange and blue.

Inspired by another SPÖKA mod I decided to also modify such a light, but instead of wirelessly communicating with the device, I wanted to be able to control it through USB. As the power requirements of the SPÖKA light are very low, it can easily be powered through the USB as well.
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