Can you help me understand samples, trigging and trace display

[dschultzca]

Hi:
I know this may be a bit off topic... I have a DSO-2250 and was looking to use OpenHantek on Ubuntu. I was able to compile the code for both the abandon openhantek project and this project's last_legacy_support branch but in either case the scope shows no signal trace (on Ubuntu or Windows). It does show a red line on the extreme left vertical grid, as in this screen shot.

If I fiddle with the Sample Rate and reduce it quite a bit I can get a trace to show (1kHz 0-2VDCpp cal out signal), but it is not at the correct voltage level or trigger point (the centre of the screen and 50% of the signal level, the green +).

Is there any documentation about how the position, samples, record length are set or determined and how the data is then selected to fit on the display area?
I added a few debug lines to HantekDsoControl::setPretriggerPosition in hantekdsocontrol.cpp to report the trigger position and then the resulting positionSamples, recordLength and Pre/Post position values.
As I adjust down to 100kS/s I get this output:

Dso::ErrorCode HantekDsoControl::setPretriggerPosition(double position) {
    qDebug("0 position: %g\n", position);
0 position: 0.0025

    case BulkCode::FSETBUFFER: {
        // Calculate the position values (Inverse, maximum is 0x7ffff)
	qDebug("5 positionSamples: %g\n  recordLength: %i\n", positionSamples, recordLength);
        unsigned positionPre = 0x7ffff - recordLength + (unsigned)positionSamples;
        unsigned positionPost = 0x7ffff - (unsigned)positionSamples;
	qDebug("6 positionPre: %i\n  positionPost: %i\n", positionPre, positionPost);
5 positionSamples: 250
  recordLength: 10240
6 positionPre: 514297
  positionPost: 524037

It almost seems as if the trace displayed is the last bit of the data, not the data around the trigger position and level.
I've looked through all the issues (open/closed) of the old project related to the DSO-2250 and found a few similar to this, but all the solutions seem to have been implemented in code but they do not resolve this issue for me.
If you have any suggestions they would be greatly appreciated.

[Ho-Ro]

I can remember that I restructured the triggering a lot because it did not work to my satisfaction. But this was done after I abandoned the other Hanteks and concentrated only on 6022 (the device I own). This code was already about 10 years old when I started to work on it - sometimes I think it would have been better to dump everything and start again from zero :(.
I do not know the 2250, does is have a HW trigger or is the triggering done in SW (as for the 6022)?
What will happen if you set constant positions, e.g. in the middle instead of calculating.

[dschultzca]

Setting constant positions does not help.
In the original Hantek SDK demo code there is a function that has to do with a soft trigger, but that only seems to be called when the timebase is less than 200ns. When looking at the CAL signal the timebase is around 200µs.
I noticed a couple of readme files in the source folders, I think I need to get my head wrapped around these and then I might have more intelligent questions.
BTW: x10 probe mode does not work, that's why the trace has exaggerated noise spikes on the high and low portions of the square wave. Setting to x1 makes the trace look better and brings the low part of the wave back down to near the zero line.

[dschultzca]

I've made some progress working from the last_legacy_support branch. I've added my changes to my fix_2250 branch. I also created a similar fix_2250 branch in my fork of the OpenHantek/openhantek project.

I noticed that switching to Single trigger mode in a Windows build causes this error:
ASSERT failure in QCoreApplication::sendEvent: "Cannot send events to objects owned by a different thread. Current thread 0x0x11b65bddd8. Receiver 'menuOscilloscope' (of type 'QMenu') was created in thread 0x0x194d113b2e0", file kernel\qcoreapplication.cpp, line 558

And as I mentioned before the x10 mode does not work, which was the reason I had even looked at this last_legacy_support branch, the original openhantek project did not have a x10 option (I guess I could convert it mentally in my head...).

[dschultzca]