Real Time Systems | 8 min | 28115
The Preempt-RT tutorial article is the most visited post on my blog. Therefore, I decided to update the tutorial to make it cleaner, and to introduce some other possible modifications and tips for solving problems.
Preempt-RT is a popular patch for the Linux kernel to transform Linux into such a real-time operating system. There is another option to get this done, and that's Xenomai (tutorial and performance tests here).
Tiejun Chen, the main responsible for the official Raspberry-Pi-RT branch, has published a video about Preempt-RT here. It includes tips, results and tests.
Getting the Sour...
Real Time Systems | 5 min | 4281
N-Queens Problem: A Benchmarking Solver for Raspberry Pi
The N-Queens Problem/Puzzle is a well-known problem that consists of placing N chess queens on an N × N chessboard so that no two queens attack each other. For example, one possible solution to the N-queens problem for N = 4 is the following:
Fig. 1: N-queens problem example (N = 4). Source: Google Optimization Tools
As you can see, no two queens are on the same row, column or diagonal. Usually the pro...
Real Time Systems | 3 min | 6022
The Raspberry Pi 3 Model B+ (Fig. 1) is now on sale and I bought one two weeks ago. The main modifications are the followings:
- A 1.4GHz 64-bit quad-core ARM Cortex-A53 CPU
- Dual-band 802.11ac wireless LAN and Bluetooth 4.2
- Faster Ethernet (Gigabit Ethernet over USB 2.0)
- Power-over-Ethernet support (with separate PoE HAT)
- Improved PXE network and USB mass-storage booting
- Improved thermal management
Fig. 1: Raspberry Pi 3 Model B+
The Raspberry Pi uses now the LAN2515 chip from Microchip instead of the LAN9514 for Ethernet and the USB Ports.
If you are looking for some Benchmarkin...
Real Time Systems | 1 min | 1463
~/rpi-kernel$ git clone https://github.com/raspberrypi/linux.git ~/rpi-kernel$ cd linux ~/rpi-kernel/linux/ git checkout rpi-4.14.y-rt
Then, you can follow the tutorial from here.
Real Time Systems | 2 min | 3704
Today I patched the kernel of a Raspberry Pi Zero W with Preempt-RT. I used the repo TiejunChina.
Update 18.03.2018: The official Preempt-RT patched Rasbian repo is here.
##~/rpi-kernel$ git clone https://github.com/TiejunChina/linux.git # update 18.03.2018: old repository## ~/rpi-kernel$ git clone https://github.com/raspberrypi/linux.git # update 18.03.2018: new repository ~/rpi-kernel$ cd linux ~/rpi-kernel/linux$ git checkout rpi-4.14.y-rt # today the kernel version is 4.14.22 # with rt17 resulting in 4.14.22-rt17+
You can find a complet...
Real Time Systems | 6 min | 24106
You can still read this article, but a new tutorial is available here:
There are a lot of tutorials for Raspberry Pi kernel patching using Preempt-RT, but I needed about 15 hours to get it working! I hate Kernel patching! and I have to say, that's not my first time. I have a system working with Ubuntu, RTAI and an Ethercat master. I patched the system more than once. But it is/was always a new thing! and It costs a lot of tim...