AD3, Waveforms - Viewing decoded I2S signal in oscilloscope

[Jonathan MB]

Hi everyone,

I'd like to compare the I2S input to the anlog output of a Class-D Amp in "Scope" in Waveforms. With V3.22.27 this is kindof possible by first adding a digital I2S channel and then adding a custom Math channel with the formula "I2S". However this doesn't doesn't apply the two's complement claculation and always shows both channels, resulting in a chopped waveform compared to the . Is there a way to also apply the Settings for the digital I2S channel (especially "Format:" and "Show:") to the waveform displayed in the scope?

Here's a screenshot. The green waveform is the current way it's decoded it and the bottom black waveform would be the ideal version:

I've tried to cheat it a bit by manually "decoding" the two's complement in the custom math function but I'm not able to get rid of the chopping.

Thanks! 

Ps. to everyone working on this project, it's absolutely incredibly how much is possible with such an inexpensive tool and great software! I'll chose Waveforms over the laggy touch screen interface of a $10,000 Rhode&Schwarz every day ;)

[attila]

Hi @Jonathan MB

Internally in Digital (Logic Analyzer) the decoded data is stored as bit sequence and the Format options (Decimal/Unsigned, Two's Complement, Hex...) are only applied for display.
The Scope/Math channel takes the raw decoded data which is unsigned... I'll try to solve this problem.

Thank you for the feedback.

[attila]

Hi @Jonathan MB

The latest version respects the digital format in Math.
(Digital format change will not cause Math channel update. It will be recalculated only on new capture, data/tab, math function change...)

[Jonathan MB]

Sorry for the late reply, changing project priorities, the usual...

Anyway, that looks great, thanks!
Also, just in general, the level of support in this forum and especially by you is incredible! Thank you so much for making a $100 range measurement equippment easier and faster to use than above 10k professional scopes!