I finally brought up my BeagleBone AI with a 25mm x 7mm fan firmly screwed into the heat sink using M2 or
M3 (they were salvaged so I don't know for sure) machine screws. It was a lot quieter than I was expecting
although I don't believe it is running at the advertised 10K RPM. Attempting to update the software with
apt-get upgrade (after doing apt-get update) died with the message "FATAL -> failed to fork" which turned out
to be a low memory problem. The Getting Started program from the desktop was running the cloud9 IDE in
the Chromium browser so I shut that down and did the upgrade again and it worked. I had no problems with
any of the other updates after that.
The next thing I did was go look for where the SoC temperatures could be read and I think I found them several
sub-directories deep in the /sys directory. I do wish that there was a standard directory to put these in as
everybody puts them in very different places in the /sys directory. There are 5 different thermal zones and
each one has a directory in the /sys/devices/virtual/thermal/ directory named thermal_zone0 - thermal_zone4.
To display the temperature for thermal zone 0 use this command:
debian@beaglebone:~$ cat /sys/devices/virtual/thermal/thermal_zone0/temp
47000
debian@beaglebone:~$
The response, 47000 (your mileages WILL vary) is 47.0 deg. C.
At the time the AI was mostly idle with me on a terminal inside an LXDE window. The temperatures I was
reading were within a couple of degrees C across all the zones. There are many thermal management
configuration files in the thermal_zoneX directories and it would be great to get documentation on what/where
the thermal zones are as well as the thermal management settings used for them.
While the idle temperatures were OK for checking out and doing light work on the AI I'm going to have to
come up with some serious thermal solutions. A 40mm fan is the biggest you can get between the GPIO
headers and I don't know if that will be big enough when you start loading up several of the more interesting
cores.
