Products > Test Equipment

A newbie needs some help with my first DSO

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tggzzz:

--- Quote from: bdunham7 on May 31, 2024, 03:29:35 am ---
--- Quote from: awakephd on May 30, 2024, 07:01:33 pm ---But now that I know, it all seems so simple, and I feel so delightfully empowered ...

--- End quote ---

Lots of memory points are handy on occasion, but to really be able to use an oscilloscope you have to understand triggering.  And that is not simple.  Most scope work (or at least a lot of it) can be done with a few thousand points.  I even have one with less than 1k points and while that can be a limitation, it is pretty good at what it does.

--- End quote ---

Very true.

For complex triggers related to digital signals, logic analysers and protocol analysers excel. They are much more effective (than scopes) at reducing the amount of non-information the user needs to ignore. That leaves us to concentrate on the useful information.

As with all things, carefully select the right type of tool for the task.

nctnico:

--- Quote from: Someone on May 31, 2024, 05:04:26 am ---
--- Quote from: nctnico on May 30, 2024, 10:38:07 pm ---Capturing beyond the screen helps to look at the cause & effect of what has been captured.
--- End quote ---
You're really going to push your single minded position that this is the true/only/correct way to do things? While conveniently avoiding mentioning the use of a zoom window to see everything simultaneously without any hidden surprises...

--- End quote ---
I'm not pushing anything on anyone. I want to show what is possible; how making measurements can be more efficient and effective. Just showing how to potentially use a tool more effectively depending on the situation. I leave the choice to the reader to judge whether it is useful for them or not. It is actually you who wants take options away from people in order to make everyone adhere to your limited, single minded way of thinking.

In the end there are more ways to skin a cat and some problems are better solved using a different approach which may not be obvious to those who never deal with such problems. You are kind of like my neurologist telling my surgeon on how to operate on my wrist. The neurologist complained the surgeon wanted to make a large cut in the palm of my hand leaving a big scar so his suggestion was to make a small cut on my wrist what would result in a much smaller scar. What the surgeon knew is that he could blend the scar in with one of the many creases in the palm of my hand and thus making the larger scar invisible. The neurologist overlooked that as surgery is not his field of expertise. Both have studied medicine, both are medical doctors but then specialisations and problems they deal with diverted.

2N3055:

--- Quote from: tggzzz on May 31, 2024, 07:29:30 am ---
--- Quote from: bdunham7 on May 31, 2024, 03:29:35 am ---
--- Quote from: awakephd on May 30, 2024, 07:01:33 pm ---But now that I know, it all seems so simple, and I feel so delightfully empowered ...

--- End quote ---

Lots of memory points are handy on occasion, but to really be able to use an oscilloscope you have to understand triggering.  And that is not simple.  Most scope work (or at least a lot of it) can be done with a few thousand points.  I even have one with less than 1k points and while that can be a limitation, it is pretty good at what it does.

--- End quote ---

Very true.

For complex triggers related to digital signals, logic analysers and protocol analysers excel. They are much more effective (than scopes) at reducing the amount of non-information the user needs to ignore. That leaves us to concentrate on the useful information.

As with all things, carefully select the right type of tool for the task.

--- End quote ---

Since it is a beginner asking, you better explain what type of device you consider "logic analysers and protocol analysers".
Devices you are referring to are not manufactured anymore.

Today when you say "logic analysers and protocol analysers" people think you mean Saleae type USB device.
Which basically have no triggering to speak of, only very rudimentary one.
Actually, one of the reasons why some people buy MSO scopes is that they have better triggering than Saleae type devices.

tautech:

--- Quote from: awakephd on May 30, 2024, 02:06:03 pm ---To take a practical example, if I am trying to decode some messages on an SPI bus, here is what I think I am understanding: On the Siglent, I will need to show "all" of the messages on the screen to capture them - even though at that point they will be so squished together than I can't discern the content of any of the messages. Then, once capture, I can zoom in and scroll through to see the actual content of the messages. Have I got it right?

--- End quote ---
To a point.
Ideally we always want to see a truly stable waveform which signifies trigger settings are correct at least for basic decoding.
While there are several shortcuts to get a result my advice to get accustomed to the absolute power of the trigger suite you have.
Some KISS examples using a single channel for UART.

To get a properly stable waveform you need to prevent retriggering within a packet using a Holdoff time setting a little longer than a packet. How long is a packet is the first thing we need to know and for this we need get a few packets on the display and press Stop and eyeball its width against the graticules.
For these examples a 60ms Holdoff is just adequate to get rock solid stable triggering.
However, while we are still in the trigger menu, we need set the correct edge which for most protocols is Idle High so we need a falling edge trigger to mark the beginning of packet data.

Now we should have sound triggering however with the H Pos mid display there's only half the display to show full packets and their decode so we need move H Pos to the left with the encoder and set it in place with Utility/System Settings/Ref Position with H Pos set to Position.

The back of the job is now broken and just decode settings remain, assigning the correct channel/s and Threshold levels, Idle High in this case, baud rate etc.

As has been discussed Zoom mode can be useful now to display a # of packets to permit panning through them and the zoomed window for each packet decode or each byte.

Hoping the attached screenshots are of assistance.

Someone:

--- Quote from: nctnico on May 31, 2024, 08:14:52 am ---
--- Quote from: Someone on May 31, 2024, 05:04:26 am ---
--- Quote from: nctnico on May 30, 2024, 10:38:07 pm ---Capturing beyond the screen helps to look at the cause & effect of what has been captured.
--- End quote ---
You're really going to push your single minded position that this is the true/only/correct way to do things? While conveniently avoiding mentioning the use of a zoom window to see everything simultaneously without any hidden surprises...

--- End quote ---
I'm not pushing anything on anyone. I want to show what is possible
--- End quote ---
By only suggesting a single method that is inferior in the majority of situations? That's not one-sided, misleading, or pushing at all.... [/s]

Persuasive language and trying to claim the majority in a corner case you invented is disingenuous. Misleading. Adding noise.

As always you conveniently leave out all the preconditions nesscecary for your corner case to be valid, and then conveniently expect people new to the conversation to already know that. Awful lot of hand waving and misdirection to push your nonsense for some reason.

Want to present it plainly/fairly? You won't get any push back, but rather you come back time and time again with the inflammatory and leading pronouncements.

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