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RealtimePi – out of the box real-time RaspberryPi Raspbian October 9, 2017

Posted by GuySoft in linux, open source, programming.
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RealtimePi logo

RealtimePi logo

Hey all,
So it started as a curiosity, and it looks like its working. I made a Raspbian-based distro that ships with a realtime kernel called RealtimePi. You can download the latest here.  It’s open source, sources are here.

A realtime system means its deterministic, it means you should know how long things take to run. They way to do is is to apply a patch to the linux kernel that makes it non-preemptible. To explain – Preemption is the act of temporarily interrupting a task being carried out by a computer system, without requiring its cooperation, and with the intention of resuming the task later.

This is useful for building hardware and robotics, low latency audio and other gpio because there are no surprises when it comes to timing. It seems like something good to try out with the RaspberryPi, because of the GPIO and IOT capabilities.

Bundled with CustomPiOS you can build your customized realtime-kernel device.


  • Both armv6 and arm v7 are supported! Aka all versions of RaspberryPi to date!
  • 4.9.52-rt37-v7 with PREEMPT kernel
  • Easy way to set up the network using realtimepi_wpa_supplicant.txt in the boot partition

Steps to install

  1. Download the image here
  2. Unzip and flash it to an SD card (small enough to fit a 2GB card)
  3. Open newly flashed image and edit two files, one for the wifi, and one for the bot token:
  4. Put in realtimepi-wpa-supplicant.txt your wifi address (skip if using Ethernet cable). Here is how it should look:

You can test the realtime kernel is enabled, by running in the commandline

uname -a

You should see something like this, note PREEMPT RT which indicates its realtime:

 Linux realtimepi 4.9.52-rt37 #1 PREEMPT RT Fri Oct 6 22:29:28 UTC 2017 armv6l GNU/Linux

The line should  look a little different for armv7

I am not an expert with actually building realtime systems, so input on how it preforms, and examples would be appreciated!


How to reuse your old Raspberry Pi as a Telegram-controlled Alarm Clock – AlarmPi August 14, 2017

Posted by GuySoft in diy, Electronics, open source, programming, python, Uncategorized.
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RaspberryPi Alarm clock

RaspberryPi alarm clock

Hey all,

So do you have a RaspberryPi not doing anything at home? Got that 2GB class 4 SD card that you just don’t know what to do with it? Well this guide is for you! It will let you turn your Pi in to an IOT alarm clock, no code, no complicated commands, just flash, edit two text files and you are good to go. The alarm clock is controlled from Telegram, so you can set it and turn it off from your smartphone. I find that usually using my phone wakes me up. So it’s useful for me. You can also edit the alarm and use any mp3 file you want.
The code is all available in github. AlarmBot is the Telegram Bot. An AlarmPi is the distro (built with CustomPiOS yet again). (more…)

ElectricSheepPi – Use your spare RaspberryPi to run evolving digital art! July 18, 2017

Posted by GuySoft in open source, programming.
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Electric Sheep running on a RaspberryPi

Electric Sheep running on a Raspberry Pi

Hey all,
So its been a while since I had time to release something fun. After developing CustomPiOS I thought I might write something to demonstrate how easy it is to make your own RaspberryPi distribution with it. So I made one that runs Electric Sheep on boot. Its called ElectricSheepPi.
Electric Sheep is a collaborative abstract artwork that keeps evolving as you vote for “sheep”. So it makes nice visuals and is great to play on a spare screen and Pi. Raspberrypi 2 works, Raspberrypi 3 is recommended for smooth visuals. You can see examples of the visuals on youtube.

To run it

  1. Download the image
  2. Flash it like any distro
  3. set up wifi, set your wifi settings with the file electricsheep-network.txt or electricsheep-wpa-supplicant.txt.
  4. Plug to HDMI display, internet and boot

Its easy to write a custom distro with CustomPiOS!

To write I had to write a module for CustomPiOS, it was just 32 lines mostly copied from the electric sheep install manual. To make stuff start on boot I used the gui module which lets you start any gui application full screen at boot, that’s 2 lines in the config file.

Thank you Doc’s Tech for hosting the image yet again!