Course notes: Ansible on OSX


Notes from Jeff Geerling’s Ansible 101 videos.

Side note: Jeff uses a 2016 13″ MacBook Pro (no touchbar), at the start of the series, but the batteries keep on swelling causing a bulging keyboard and need replacing (twice). This model was upgraded to a newer model after a few episodes.

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OpenCV trackbars and OS X


Notoriously poor coding by the OpenCV group here, with trackbars being barely functional.

The two main issues are:

  • Trackbar value is not displayed
  • Trackbar ordering is not the same as the order in which they are coded
    • In fact is is apparently random, or pseudo-random – it is a logic, but it is not clear what that logic is

Additional issues are:

  • Named windows containing only trackbars do not move with moveWindow()
  • Named windows containing only trackbars do not resize with resizeWindow() – check this!!!
  • Code execution pauses when a trackbar is adjusted
  • Performance hits
    • When trackbars are in the same window as the image being adjusted

I have seen these issues consistently in Python. I am not sure if they all occur in C++ as I haven’t tested for them (yet).

Version info:

  • OS X: High Sierra
  • Python 3.7/3.9
  • OpenCV:

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Course notes: Another Arduino based robot car


Notes from Robotics Training LESSON 1: An Introduction to Robotics for Absolute Beginners

Yet another robot car, based on Arduino. This project uses the Elegoo robot car.

It’s interesting to compare this one with the Murtaza car projects. The movement functions are more sophistimcated on this project.


Note that this course code is for V3 of the Elegoo car. V3+ and V4 will not work, without some modification.

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