Trigger on rising edge not working

[ForgottenTales]

Describe the bug Setting looks like this:

I can sometimes catch a falling edge of the signal. But the rising edge is never catched. Eventho the signal very clearly is moving above the threshold. It does not really matter which trigger mode is used.

To Reproduce

Steps to reproduce the behavior:

1. Connect probe to some low signal
2. Choose Trigger mode normal and set the trigger level somewhere between low and high value
3. Pull signal to high.

-> Trigger not engagin.

Expected behavior Trigger fires and picture freezes.

Computer environment (please complete the following information):

• OpenHantek version: 5012dc39e1349846a6474db3abc948ee8f4604ba
• OS: Ubuntu 20.10
• Video hardware: GeForce GTX 1650
• C++ compiler version: gcc (Ubuntu 10.3.0-1ubuntu1~20.10) 10.3.0

Scope device (please complete the following information):

• Device Hantek 6022BE, FW0207
• Program top line: OpenHantek6022 (Build 796) - Device DSO-6022BE (FW0207)

[Ho-Ro]

• 1st remark - your version is very old (5012dc3 is from 27-Dec-2020), you should update either to latest release 3.2.4 or the latest unstable (this contains more or less minor fixes for 3.2.4).
• 2nd remark - what kind of signal do you want to catch? Due to the missing trigger HW of the scope OpenHantek6022 is best suited for repetitive signals in the extended audio range (1 Hz .. 100 kHz). If you want to catch single events reliable - get another hardware. A DSO works like this: capture the input signal into a buffer (e.g. for 20 ms/div * 10 div = 200 ms) and when the buffer is filled refresh the screen with the new buffer content. This would give one refresh every 200 ms for a free-running signal. But to get a standing display you want to trigger. The Hantek6022 don't have any hardware trigger, so triggering is done completely in SW. Therefore the program samples (free running) into a bigger buffer that equates twice the screen size, searches for a sufficient trigger point and displays the corresponding section of the buffer. This leads to a refresh every 400 ms. If there is no trigger condition the sampling starts again until you catch the slope. You should check how it is done. I checked your setup (20 ms/div on CH2 - rising or falling slope) with a ~0.5 Hz square signal and get a perfect triggered display in Normal mode, with Single I also catch the slope after a while. Auto does trigger sometimes with free running in between (how it is intended).

[ForgottenTales]

Hi @Ho-Ro

Thanks for the very fast response. Actually I want to catch a single edge from low to high and I am having problems to do so. I need to analyze a timing issue during power up. So I have 2 channels and have to see how fast second channel rises after first channel (power supply) has gone high.

Okay. with new Version I could get it to work sometimes. You can see in the video how the setup is. Also the refresh rate seems a lot slower than 400ms? Maybe there are some lost buffer due to some performance issue? Seems to also happen more frequently with big buffers.

https://user-images.githubusercontent.com/7306985/131012305-463b0ea8-f065-4e1b-8f7f-898a58ff00a9.mp4

[Ho-Ro]

As usual with scopes timebase 200 ms means 200 ms/div (as well as 2 V means 2 V/div), the screen width is 10 divisions (= 2 s) -> the screen is refreshed every 4 seconds. Typical dead time between two buffer acquisitions is 1 ms. As said, if you want to measure sporadic signals, then better use PulseView with a cheap logic analyser, e.g. this one, or another so-called "Salae clone".

[ForgottenTales]

Hi Martin,

okay. Thanks for your help. So I guess we can close this case.