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Coreboot for the Lenovo T420 / T420i with Ivy Bridge support

Usually I tend to decline offers for old laptops, because I have too many projects anyway, but when a friend offered me a broken T420, I thought “Hmm, good opportunity to try out Coreboot…”. Because, why not?! The laptop The device arrived in a sad state: It was dirty, had old stickers on it, itsContinue reading “Coreboot for the Lenovo T420 / T420i with Ivy Bridge support”

Using a 24C256 / 24LC256 EEPROM on Raspberry Pi with device overlays

For my HappyPlayer project I needed non-volatile storage for some settings, but I wanted to make the RPIs SD card read-only to prevent data-loss or file system corruption in case of power loss of the whole device. So I used an EEPROM (Atmel 24C256) to store the settings in regular intervals to be able toContinue reading “Using a 24C256 / 24LC256 EEPROM on Raspberry Pi with device overlays”

Compiling SDL2 / image / mixer / ttf for the Raspberry Pi without X11

If you want accelerated SDL2 graphics when on the console, e.g. on Raspbian Lite you don’t want to use X11. You could get away with just installing SDL2 from the repository, but my SDL2 version had problems regarding touch screens, so I needed to recompile. Also if you install any of the libsdl2* libraries aContinue reading “Compiling SDL2 / image / mixer / ttf for the Raspberry Pi without X11”

Use a rotary encoder and button on Raspberry Pi with device overlays

For my HappyPlayer project I needed to control the audio volume using a rotary encoder and GPIOs. I used device tree overlays for this. The encoder used is a standard type with an additional momentary switch when you press it. It needs 4 pins: Common GND -> Pi GND Momentary switch -> GPIO 6 RotaryContinue reading “Use a rotary encoder and button on Raspberry Pi with device overlays”

Overclocking the Raspberry Pi Zero / Zero 2

As my OctoPi installation was a bit slow on my RPi Zero I wanted to try overclocking it. I found a lot of different reports about overclockability and temperature, so I did some measurements myself. Make sure your CPU governor is set correctly Otherwise you CPU will not clock to the maximum clock speed youContinue reading “Overclocking the Raspberry Pi Zero / Zero 2”

Booting up OctoPi fast(er)

OctoPrint is awesome, but especially if you use a Rasperry Pi 0 you want to make it boot up as quickly as possible. Here’s what you can do. I compiled this from different sources on the internet, e.g. this. Warning: Make sure you have OctoPrint up and running and make a backup of your SDContinue reading “Booting up OctoPi fast(er)”

Overclocking SD cards on the Raspberry Pi

Warning: Overclocking SD cards can corrupt your data and possibly damage your SD card! If you want better SD card speed and have an UHS-1/3-capable SD card, you can make the Pi run it with more than the standard of 50 Mhz. I tried this with a Rasperry Pi 0 (the non-W variant) and aContinue reading “Overclocking SD cards on the Raspberry Pi”

Running GUI applications over SSH on a Raspberry Pi

Sometimes you have a RPi attached to a screen, but no keyboard or mouse attached and want to run GUI applications on it via SSH. This will also let you cross-compile RPi applications on a development machine and test them on the real machine. Prepare the RPi for ssh access To enable SSH access onContinue reading “Running GUI applications over SSH on a Raspberry Pi”

Signing your kernel modules on Ubuntu 16.04

I have an Asus UX3410UA laptop. To silence the fan I use ACPI calls to adjust the fan tipping point. See this. This needs the kernel module “acpi-call-dkms” for being able to run the “acpi_call” executable. If secure boot is enabled on a computer this module will not load if it is not signed andContinue reading “Signing your kernel modules on Ubuntu 16.04”

Compiling Android x86 5.1.1 from source

I had this Medion Lifetab P8314(.2) tablet and kernel sources from the vendor and wanted to compile Android x86 5.1.1 64Bit for it. Compiling Android x86 is described in detail here, but there are some caveats, so I’ll noodle it all down here from the beginning. Note that I use Ubuntu 16.04.03 as a hostContinue reading “Compiling Android x86 5.1.1 from source”