DSO firmware version 3.43

[lygra]

@BenF

@lygra

Tonight while completing tutorial #7, I noticed that when in AUTO mode, the trigger edge symbol fails to turn red with loss of trigger. Appears to be an oversight from previous version.

When in AUTO mode, the Nano will always trigger (as it is forced after 100 ms if no trigger is found) and so the waveform display will be updated and the trigger symbol stays green. The idea here was to keep it simple: If the trigger symbol is green, the displayed waveform is “fresh”. If the trigger symbol is red, we’re looking at “old” data.

My concern is that the user may be looking at a jittery waveform and not realize that changing the trigger level/sensitivity may very well improve the waveform stability. By definition, AUTO means the display is continually being refreshed. The following example demonstrates my opinion:

1. Input the 1Khz waveform with VD=1V/Div and TD=200us/Div and then raise the trigger level well above the signal, then observe for 30 seconds. You will observe two things, waveform jitter is present (not triggered) and the transition symbol will occasionally flicker trying to show red.

2. Now place the trigger level inside the waveform and the waveform becomes rock steady. A complex and/or unstable input signal waveform could have much more dramatic behavior while not being triggered in the AUTO mode.