Raspberry Pi 2- What works and what doesn't!


Unfortunately there’s no way to recover your old Raspbian OS, it’s gone, kaput!

That’s a curious error- it suggests that i2c is setup correctly but that the system is having trouble communicating with the PiGlow. Is it seated on the header firmly and in the right place?

Just to be sure, try:

ls /dev/i2c*


i got this

pi@raspberrypi ~ ls /dev/i2c* /dev/i2c-1 pi@raspberrypi ~


i got this

pi@raspberrypi ~ ls /dev/i2c* /dev/i2c-1 pi@raspberrypi ~

what should i do now?


Well i2c is definitely set up- at least it looks that way. What about:

cat /boot/config.txt | grep dtparam

Have you double-checked that the PiGlow is seated correctly?


sorry! i am such a retard! i was using the wrong ip address so that means that everything i was typing in was going onto my security camera rips. can we please start over?


Whenver i try to do that i get this

Traceback (most recent call last):
File “arm.py”, line 7, in
from piglow import PiGlow
File “/usr/local/lib/python2.7/dist-packages/piglow.py”, line 16, in
from smbus import SMBus
ImportError: No module named smbus


Okay, that should be easy:

sudo apt-get install python-smbus


its working!

You have been such a help! can i donate through paypal?


Haha! You’re very kind, don’t worry about it. Save it for more cool toys!


I’ve been working on the USB display we’re selling, which also has problems with Pi 2, and is a hassle to get working on Pi 1.

Here it is working on a Pi 2:


I haven’t written step-by-step instructions for doing this yet because it involves a complete kernel recompile and I’m hoping the final process could be a little easier!


Any news on the Unicorn HAT?


We’ve got a very hacky and very temporary fix up and running which will get something out of your UnicornHAT, but it’s not great!

It’s for advanced users only, and the code is in GitHub here: https://github.com/pimoroni/unicorn-hat

If you want to try it:

sudo pip uninstall ws2812 unicornhat
git clone https://github.com/pimoroni/unicorn-hat
cd unicorn-hat/python/ws2812
sudo ./setup.py install
cd ../UnicornHat
sudo ./setup.py install
sudo python ../examples/random_blinky.py

Good luck!


Surely if it works then that’s great, no? What’s the problem?


There are definitely variations of “works” and this is pretty low on the scale! It sort-of works, but doesn’t push out all the pixel data properly, missing pixels. If you fire out enough data, fast enough, then your own persistence of vision fills in the gaps, but it still looks pretty awful.


Haha. Weird. Hence using the blinky example.

Any ideas what the issue might be?


We believe it’s related to the memory used in DMA being cached, so the data being output through PWM isn’t the data we’re sending it. The hack currently tries to flush the cache with empty data but this only works some of the time… with mixed results!


It works! I’m blind now, but at least I got to see it once!


Hurrah! Thank @Jon for persevering in the face of adversity. We’re still looking for a real solution, but this should let you damage your eyesight in the interim.


Well chuffed, it gets my LEDs blinking! Thanks for all the effort :)


i thought my unit was broken. For now at least it gets four LEDs on the upper right of my unicorn hat to light up. Hope things will be okay soon. Thanks for the effort guys!