Scope freezing after going out of range (?)

drtrigon commented 5 years ago

After solving #55 the PSU does not work anymore. I have to use "Pause" on Scope CH1 twice (Pause on, Pause off) in order to make the voltage setting for the PSU work again.

Also the Multimeter shows totaly different values compared to the Scope (the Scope agrees roughly with the PSU settings).

By the way what is the maximum Amplitude for the Signal Generator? I never get more than close to 3.3V. is there a calibration step for the Signal Generator (or am I just to tired and start hallucinating... ;)?

EspoTek commented 5 years ago

Just tested and it looks like those features are working fine (at least in the normal case). Here is the test I performed:

 - Connect scope CH1 to PSU Vcc
 - Connect scope CH2 to PSU GND
 - Connect board to PC and run the software (EspoTek_Labrador-0c1604c-x86_64.AppImage)
 - Turn on all 4 oscilloscope CH1 stats (max, mean , min, rms)
 - Unlock PSU, set to 8V.  Scope stats show approx 8V.
 - Turn off scope, turn on Multimeter++.  Multimeter++ stats show approx 8V.

That said, there are some quirks which are not clearly apparent:

Multimeter++ uses CH2 as a reference voltage, whereas the oscilloscope uses GND. If CH2 is disconnected, it will float to 1.65V, so it's likely that you were measuring the difference between PSU voltage and 1.65V. (bonus: If you ground CH2, the multimeter can function as a 12-bit scope with amplifier noise calibrated out! Really handy for taking more accurate measurements.)
The Signal Generator uses the same voltage rails as the PSU. You need to set the PSU voltage to at least 1.5V above the peak of the signal generator to prevent clipping. There is no calibration step for the signal generator, but there's no reason there couldn't be.
Also, the PSU has a lock on it. Are you sure you unlocked it PSU before trying to move the slider?

I'll leave this issue open for now, though. While I can't say there's a software bug, there's definitely some UI improvements to be made. The user should be notified of these quirks when they first enable the multimeter or set the signal gen amplitude to a high voltage.

drtrigon commented 5 years ago

I followed the steps you suggest. After "Unlock PSU, set to 8V" the scope stats stay frozen at around 4.5V. In this case the trick mentioned (pressing "Pause" on scope CH1 twice) does NOT help. I first have to change the range Vmax such that the signal becomes visible, e.g. 10V and THEN press "Pause" twice in order to make it work again.

Here in detail the steps needed to reproduce using EspoTek_Labrador-0c1604c-x86_64.AppImage (on kubuntu 14.04):

connect labrador to usb
connect CH1 to PSU Vcc
start EspoTek_Labrador-0c1604c-x86_64.AppImage
answer no when asked about doing a calibration
set range Vmax to 7V already here is obviously something wrong, as the scope trace does not show any noise at all
change PSU and see that nothing happens on the scope trace
press "Pause" twice and see how it starts working again

I did unlock the PSU in the first place as the digit changed, actually I assume it's the scope that freezes. Changed the topic accordingly.

About the quirks you mentioned:

RTFM to myself ;)) actually it is quite nice to have CH2 as a ref
why is in DMM mode a scope trace shown? it actually that also has CH2 as ref is that a differential scope mode? same speed as scope? (hope it's not RTFM again ;))