Your Dot3k / Skywriter / etc doesn't work after running rpi-update or upgrading for Pi 2


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##Help, I updated my SD card ready for Pi 2, how can I get things working again?

Raspbian for Pi 2 has device-tree enabled by default, so it’ll cause the same problems as an rpi-update. To enable SPI and I2c it’s easiest to simply run:

sudo raspi-config

And then enable them in the resulting menu- which now supports the necessary additional options for enabling SPI/I2C under device-tree.

##Help, I’m running on a Pi 2 and everything is broken or slow!

Read above if you’re having missing directory errors, or other things associated with I2C or SPI not being enabled. If you’ve done all that and got Dot3K, or another product, running but find that it’s really… really… really… sllloooooowwwww… then you’ve just run into a bug with device-tree that prevents high resolution timers from running properly.

Every time python runs “time.sleep” it ends up sleeping for way, way longer than it should under normal circumstances resulting in everything running painfully slow.

The solution to this problem is known, and hopefully coming to a Raspbian near you!

##Help, I updated using rpi-update, how can I fix my Pi?

If you’ve recently upgraded using rpi-update and you didn’t know what you were in for then you’ll need to get your firmware back on track with the latest stable and tested Raspberry Pi release:

sudo apt-get install --reinstall raspberrypi-bootloader

##What’s this device-tree stuff, and what does it mean for me?

Please read this thread for information:

http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=97314

And read more about Device Tree here:


Word of caution: Don’t run “rpi-update”.

No, really. It’s not meant for the average user, and you should only run it if you really know what you’re doing. Stable and thoroughly tested kernel updates will come as part of an “apt-get update”, you don’t need to stay on the bleeding edge.

Note: I found myself falling into the trap of erroneously telling people to try this “rpi-update” as solution to some problems. Whoops! To confirm: “rpi-update” is not meant for general use. Don’t run it unless you absolutely have to!


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