Reading BeagleBone AI Temperatures

Thanks gdstew

This is just the information I'll need soon. In a few days I'm expecting my USB-C cable and then I'll be powering up my BB-AI for the first time - having followed the various threads I'm keen to watch the temperatures.

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.

I too have noticed this. I think they got over zealous using TEMP in RAM... I plan to dial it back some. Also add external storage. The 16 G eMMC is a bit small. I will blog the results of tuning this over the weekend.

Without a fan, my temp0 was 67C. Too toasty for me... Thanks gdstew for finding how.

I would have imagined all these BB-AI were the same, however very cautiously I too ran the sudo apt update and upgrade from the Loud9 IDE and it did work. No errors!

I'm connected via Ethernet from a router/switch and connecting in via the Cloud9 web server from Mozilla Firefox.

I just attached a bash shell script I wrote to read one or all temperature zones on a BeagleBone AI. There is a bin directory in the debian users home

directory directory and I copied the script from a micro sd card to /home/debian/bin. The home/bin directory is not in the environment PATH variable

so either have to add it to PATH, include the path with the file name when you execute it, or copy it somewhere already in PATH. I chose to copy it to

/usr/local/bin using the command:

  debian@beaglebone:~$ sudo cp bin/ai_temp.sh /usr/local/bin

In order for the debian user to execute the script the file permissions have to be changed to allow it with the command:

   debian@beaglebone:~$ sudo chmod o+x /usr/local/bin/ai_temp.sh

After that:

To see all temperature zones type ai_temp.sh from the command line,

To see a specific zone temperature type ai_temp.sh X where X is the zone number from 0 - 4. If you type in an invalid zone number you will get an

error message.

This script does use bash specific commands, specifically the ones used to extract characters from the temperature returned by the cat command.

It also makes a couple of assumptions about the number of digits in the temperature. The first is that there are no more that two digits to the left of

the decimal point. This is probably a safe assumption since the script will probably not be running if the AI temperature is > 99 deg. C. The second is

that there there are two digits to the left of the decimal point. This is a reasonable assumption because the AI is not going below 10 deg. C unless

some type of extreme cooling is used.

From testing the script it looks like zone 2 is the dual core ARM Cortex-A15. It is always the highest temperature by around 2 degrees C.

Good Work you did there. Though, to be sure, you can always contact ti community, and get an official answer.

The pre-attached heat sink has M3 holes spaced 20x20 mm.

The height of the heat sink clears the USB type A socket, and all other components on the board except the 46-way header sockets and the Ethernet socket.

You also need enough room between the fan and any cape above it to allow the air to flow as freely as possible for more efficent cooling and to keep the load on the fan motor as low as possible.

I've wondered how many existing capes have header pins long enough to properly clear the fan and allow them to be used on the AI. As I said in another post, I understand why the wanted to

keep the BeagleBone form factor, but due to the thermal  problems everybody is seeing I think that it was a mistake. One possible way of getting around that would have been to put the GPIO

headers on the bottom of the board instead of the top. You could still use existing capes by using headers with male pins on both sides to connect between them and leave the top of the AI free

for a larger heat sink/fan. I have a Snickerdoodle Xilinx FPGA board that had this as a build option. It also had an option for a tall copper heat sink for the FPGA. Mine has both.

If you look at the /sys/devices/virtual/thermal/thermal_zoneX/type value, it gives you a 'name' for each of the thermal zones, as such:

thermal_zone0/type = cpu_thermal

thermal_zone1/type = gpu_thermal

thermal_zone2/type = core_thermal

thermal_zone3/type = dspeve_thermal

thermal_zone4/type = iva_thermal

gpu_thermal is clearly the SGX544, dspeve_thermal seems to be a combined thermal zone between the C66x and EVE cores, iva_thermal is the IVA-HD video engine.  Between the cpu_thermal and core_thermal, I would guess that you're right with zone 2 (core_thermal) being the actual A15 cores, with cpu_thermal being an overall package temperature.

When idle, I'm finding iva_thermal is the highest, despite not decoding any video. 

I've installed a fan (https://www.digikey.com/product-detail/en/nidec-copal-electronics/F251R-05LLC/563-1111-ND/1165505) so it's staying below 55 C while doing apt updates.  Works very well (and very quiet), although the fan connectors can pop out if you're not careful.

Thanks for the information. I plan on putting it in the script sometime in the near(?) future. However I have to think about the best way to do

it a bit first and I am real busy with a couple of other projects right now.

I'm not happy with my fan connection either. I have no problem with the leads staying put, although I am usually really careful. They just stick

out too far and are in the way as far as cases or capes go with no good solution, other than a fan cape or soldering iron, for getting them out

of the way. It was obvious that a fan would be needed, it would be nice if a fan connector was available.