Intermittent power consumption jumps on Colibri imx6

We have a very sensitive A/D pcb. We are seeing distortion of our data and have traced it to the power supply, where the imx6 is the primary load. Given the power management of the linux system, this is to be expected.

We are seeing large spikes in the data every 30 seconds very regularly - is there any process in the kernel which is operating at 30s intervals? How would we go about finding out the answers to this ourselves? I assume there are more background processes running than just those in crontab (if imx6 is even using crontab that is) and systemctl…but we wouldn’t even know where to start looking comprehensively…

Hi Steve

Could you write which Software Version for imx6 are u using? Which values are u measuring for mean and max power? What are the other loads on the same power supply?

Best regards, Jaski

We’re using the 2.7 image. Mean & Max power are within spec, they are just fluctuating wildly, I thought we could probably disable some processes to alleviate that, as our application presents a constant load to the processor, so I have to assume some linux utility is causing the spikes…

I was really asking how to check what OS tasks are running and how to start/stop them. We can figure out the power on our own if we can find the “control panel”…the request for scope shots is just prolonging the issue.

Hi Steve
Can you send a mesurement file or an oscilloscope picture? Check also if the cpu load is varying?

hi steve

you can check with ps aux all the running applications and stop them by typing kill "pid", where the pid is id of the process you want to stop.

Ok, that was a stupid question, I admit. We know ps(), but we don’t know what the origin is of all the things that show up in ps. I don’t wanna kill them temporarily with kill(), I wanna kill them permanently across reboots.

You can do it by modifying systemd control files. There are many manuals about systemd are available on internet.
I’d recommend you to start from How To Use Systemctl to Manage Systemd Services and Units | DigitalOcean
More information available here - systemd - ArchWiki