I read MagPi 84 Aug 2019 page 44 Melissa LeBlanc_Williams's article on using Rpi4 circuitPython to control a robot using two boards:
(1) BNO055 9-Degrees-of-Freedom (DOF) Absolute Orientation Module, and
(2) PCA9685 16-Channel 12-bit PWM/Servo Driver Module.
I followed the instructions to install python3, setup tools, adafruit-blinka library. I got stuck at Step 8:
pip3 install adafruit-blinka
The error message was:
cannot find version that satisfies the requirement, ... no matching distro found for adafruit-blinka
My configuration is Rpi4B 2GB Raspbian 10 buster.
Any help or tip appreciated.
Update 2019jul27hkt1629
@milliways' Rpi4B buster works OK. I am not sure if the reason is that my kernel is too old. I need to update my kernel and tried again.
I checked that my raspbian release date was 2019jun20. The latest release is 2019jul10. I guessed beside the kernel, there might be other packages or drivers out of date. I might have also installed other conflicting software when I played with other things earlier. So I guessed the cleanest solution is to start everything from scratch: download the latest raspbian, and first thing first is to install Adafruit circuit python blinka.
So I installed Raspbian (buster 2019jul10) again. The welcome screen says the release page is not ready, until some 20 days later. I guess this might cause trouble. So I exit GUI desktop straight away and start installing circuit python blinka in terminal mode.
This time everything went smoothly. My conclusion that the root cause of my installation problem is that my Raspbian dated 2019jun20 is out of date. I might also installed other packages earlier and they crash with circuit python's blinka library.
Anyway, problem solved.
Update 2019aug08hkt1121
I have also clarified my mind on why using "sudo pip3 install" first, and just "pip3 install" (no sudo) later. See this thread for details: No module named 'adafruit_circuitpython_servokit'