Does board go into low power state after being idle?

Hardware related problems and workarounds

Does board go into low power state after being idle?

Postby ninlar » Thu Jun 29, 2017 8:50 am

After I plug-in the Parallella board, it responds just fine over SSH for awhile. But if I come back an hour later, the SSH connection has been dropped, and I cannot reconnect. During this time, I don't have any programs running on the board, so it should not be overheating. My board came with the giant heat sink and made sure the thermal tape was properly placed on both the Zynq and Epiphany chips.

I have not connected a serial cable yet to see if any traces are coming across before it becomes unresponsive. I just wrote a program that sits in a loop for several hours running ztemp.sh and appending the output to a log file, to see if the temperature is creeping up over time. If the program runs all night then I guess that might support my hypothesis that the board is going into some sort of hibernate or sleep, because the program would prevent that from happening, and if it is overheating, then I should see it in the log file as it creeps up to the point where the watchdog takes action to save the board.

My question is, does Parabuntu go into a low power state if it is idle? Is there some sort of wake on LAN type of thing you can do to remotely knock it out of this state?
ninlar
 
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Re: Does board go into low power state after being idle?

Postby ninlar » Thu Jun 29, 2017 1:18 pm

Actually it turns out that the board is shutting down due to overheating. Sure enough I came in this morning and it had stopped responding and after a reboot and running the tail command on the temperature log:
Code: Select all
parallella@parallella:~$ tail temp.log
Zynq Temp: 66.3 C / 151.3 F
Zynq Temp: 66.9 C / 152.4 F
Zynq Temp: 67.5 C / 153.5 F
Zynq Temp: 67.3 C / 153.1 F
Zynq Temp: 68.7 C / 155.6 F
Zynq Temp: 68.6 C / 155.4 F
Zynq Temp: 68.5 C / 155.3 F
Zynq Temp: 69.1 C / 156.3 F
Zynq Temp: 69.7 C / 157.4 F
Zynq Temp: 69.3 C / 156.7 F
parallella@parallella:~$


So now that makes me wonder what is causing that to happen. It had no programs running other than my simple app:
Code: Select all
#include <stdlib.h>
#include <unistd.h>

int main()
{
        for (int i = 0; i < 500; i++)
        {
                system("bash ztemp.sh >> temp.log");
                sleep(30);
        }
}


Also note that as I mentioned earlier, I did receive the giant heat sink and termal tape with my board, and I have installed it.
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Re: Does board go into low power state after being idle?

Postby olajep » Thu Jun 29, 2017 3:11 pm

How to improve thermal conditions:
1. Have the board standing up on the side.
2. The headless (non-HDMI) images use less power
3. Use a fan (just need a tiny bit of airflow).

https://www.parallella.org/2014/04/30/c ... d-cooling/
A heatsink is supplied with the board but this will not provide sufficient cooling alone and a fan must be used. It is possible that a fan may be sufficient without the heatsink, but using both is advisable. Note that only a small amount of airflow is required.

The heatsink is usually enough when the board is sitting idle (with a headless image). But when you start putting load on the system it will eventually go above 70C. When that happens the parallella-thermald daemon will kick in and shut off the board to protect it from overheating.

You can monitor the temperature (Zynq Temp) with the 'sensors' command:

The thermal daemon (parallella-thermald) will shutdown the board when the Zynq on-chip thermal sensor goes above 70C to protect the components from overheating.

// Ola
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Re: Does board go into low power state after being idle?

Postby ninlar » Thu Jun 29, 2017 4:34 pm

Thanks Ol
olajep wrote:How to improve thermal conditions:
1. Have the board standing up on the side.
2. The headless (non-HDMI) images use less power
3. Use a fan (just need a tiny bit of airflow).

https://www.parallella.org/2014/04/30/c ... d-cooling/
A heatsink is supplied with the board but this will not provide sufficient cooling alone and a fan must be used. It is possible that a fan may be sufficient without the heatsink, but using both is advisable. Note that only a small amount of airflow is required.

The heatsink is usually enough when the board is sitting idle (with a headless image). But when you start putting load on the system it will eventually go above 70C. When that happens the parallella-thermald daemon will kick in and shut off the board to protect it from overheating.

You can monitor the temperature (Zynq Temp) with the 'sensors' command:

The thermal daemon (parallella-thermald) will shutdown the board when the Zynq on-chip thermal sensor goes above 70C to protect the components from overheating.

// Ola


Thanks Ola! Interestingly enough, I am running the headless image even though it is an HDMI board, but I will get a fan. I'm wondering if a small CPU fan can be powered off the board itself.
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Re: Does board go into low power state after being idle?

Postby sebraa » Wed Jul 05, 2017 10:10 am

ninlar wrote:Thanks Ola! Interestingly enough, I am running the headless image even though it is an HDMI board, but I will get a fan. I'm wondering if a small CPU fan can be powered off the board itself.
Three of the mounting screw sockets are connected to GND, the fourth carries 5V (may need slight modifications to the board). You can run a fan directly off it (that's what we use).
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Re: Does board go into low power state after being idle?

Postby redbank199 » Thu Jul 06, 2017 3:31 am

I started playing with my first Parallella board yesterday. I started with the latest HDMI version image, heat sink installed, board standing up
on the side, but no fan, the board would shut down even when the only program running was xtemp. I ended up placing a large fan blowing
air toward the board to cool it down to about 50 F degree. But as soon as I turned off the fan, the temperature started rising, and the board
got shut down in about 15 minutes when xtemp showed 70 F degree.

So the lesson from this little experiment is with HDMI image, you definitely need the help of a fan.

I prefer not to run a fan from the mounting screw socket. I am thinking about getting a USB fan, but not sure how big/small the fan can be.

Does anyone have some data on the requirements for a fan ?
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Re: Does board go into low power state after being idle?

Postby sebraa » Thu Jul 06, 2017 9:32 am

redbank199 wrote:Does anyone have some data on the requirements for a fan ?
I think that even running a big 12V case fan from a 5V supply (e.g. USB) should be enough, as long as it spins up. The required airflow is very small, especially with the bigger heatsinks in modern boards.
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Re: Does board go into low power state after being idle?

Postby olajep » Mon Jul 17, 2017 7:24 am

sebraa wrote:
redbank199 wrote:Does anyone have some data on the requirements for a fan ?
I think that even running a big 12V case fan from a 5V supply (e.g. USB) should be enough, as long as it spins up. The required airflow is very small, especially with the bigger heatsinks in modern boards.

I do this on one of my boards and it works really well.
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