Joulescope frozen - red USB text

I am currently using Joulescope UI version 0.8.16 and driver version 0.8.14. While doing measurements the UI freezes when I change the current too fast upward. It seems to work sometimes on another computer, both computers with Windows 10. When it freezes the USB indicator in the bottom right corner turns red. Only when I get the current back to where it was stable it turns back to green and the measurement continues. In the log file I get the following warning:
WARNING:2020-06-22 10:22:01, RED: d_sample_id=0, d_sample_missing_count=0

I assume it has to do with the computer. I tried to this also with only the UI open and no other USB connected - still freezing.

Hi @fma21 and welcome to the forum!

First, the indicator light turns yellow or red when samples are being dropped. Both the host software and the device handle this gracefully and return to logging data, just like you observed.

From your description, I am concerned that your Joulescope is not powered sufficiently. Can you confirm that you are connecting your Joulescope’s host USB connector directly to your host computer’s USB port? Please ensure that no hubs or docking stations are between Joulescope and your host computer.

If this does not fix the problem, here are some other things to consider:

  1. When this event occurs, is your host computer doing anything other than running the Joulescope UI? For example, are you controlling the target or power supply using your host computer?

  2. What type of current and voltage step are you injecting? Very fast edges have lots of energy. While we have tested for this, it is possible that it is coupling into the USB side somehow. We never figured out what was going on with this topic: Frequent crashes in 0.6.8.

  3. If you set your Joulescope to a fixed 10A range and then measure this event, do you see the same sample drop behavior?

I am connecting the Joulescope directly to the host computer’s USB port.

  1. I am not controlling the power supply with the computer but there are other software running. I also tried using ONLY the Joulescope UI (with no software opened in the background), but it still gets stuck sometimes.

  2. The Joulescope displays around 4.3V and 30mA. I can control the voltage with another device and want to do measurements for 3.5, 3.7 and 4.3 Volts. Especially while lowering the voltage from 4.3V back to 3.5V is can get stuck. Normally this is not a big problem, since reconnecting the USB cable solves it. But now I want to automatize the measurements with a python code, where having to reconnect the cable is a problem.

I will investigate the problem further.

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I encounter the same issue. I try to emulate a Li-Ion battery with the Joulescope. As soon as I switch on power of the battery operated device (DUT) the Joulescope freezes with the same warnings. Unfortunately power if my DUT is switched off when I reconnect USB. Then the whole procedure starts again.

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Hi @sensorsiot and thanks for reporting that you have duplicated this issue. We have not had success.

If you have a moment, I have a few questions that may help us figure out what is happening:

  1. Does the LED on the front panel under the “IN” text stay illuminated the whole time?
  2. Are you turning on power using Joulescope (current range from off to auto) or using a switch at your DUT?
  3. What is your power source? Is it the actual Li-Ion battery?

Sorry that you are seeing this issue, and thank you for your help!

One potential cause is RF noise pickup through the cables. Here’s something easy to try. Twist your IN cables together from the power supply to the Joulescope, and then twist your OUT cables together. This does two things. First, it minimizes the loop area, which will reduce RF noise pickup. Second, it will increase the inductance slightly which may also help.

If the cables pick up excessive RF signal, then it could couple into the Joulescope ground and power planes. USB’s small common mode differential range on D+/D- is particularly susceptible to this type of noise pickup.

Thank you for your answer. I am on holidays and will try it after my return.