Troubleshooting & Errata
The Raspberry Pi ecosystem is continuously changing and evolving, unfortunately this can mean that things which did work during test, may not work forever. Although I had tried to test and check everything within the book several times, as much as I wanted it to be perfect, it was inevitable with a publication of this size and the limited time I had available that some things would get missed.
My sincere apologies if you discover any errors which cause you additional hassle or inconvenience, I hope that you still enjoy the book.
I’ve compiled a list of corrections which I’ve been made aware of or have discovered since the publication of the book. While the publisher will ensure that the book is corrected, both in digital format and in subsequent reprints of the book, to avoid confusion I will also list them here so any issues can be avoided (particularly if you have an older copy of the book or have not downloaded a fresh version).
I’ve only included technical errors, or issues which may cause actual problems (any minor, grammatical or spelling mistakes I’m aware of will also be corrected in future updates).
Chapter 7 – P201
The equation for potential divider circuits is incorrect (when I re-drew the equation last minute for the final version I incorrectly included VCC in the denominator), the equation should be as follows (the resulting calculations should still be correct in the section):
Chapter 8 – P236:
Issue: Preview on camera examples are black
Although this isn’t an error as such, this issue appears to occur using the latest camera drivers (which I believe were updated after I developed the code for this section). Fortunately the fix is fairly straight forward (since everything is so modular), and the issue only affected the preview feature.
If you get black preview images then version of the camera driver you are using may have an issue with generating .gif images correctly. If this occurs you can change the preview image to use .jpg files by altering the PREVIEW_FILE name as follows:
Within cameraGUI.py change:
The .gif format was used to speed up the preview process.
Chapter 9 – P303:
The same equation diagram which was on Page 201 was also used here (so unfortunately the equation is incorrect here too):
If you spot anything else which you may think is an error or have particular difficulty with something then please do let me know. I would rather be aware of any issues and be able assist and provide solutions than for people to have problems which become hurdles to getting the most out of the book.