Siglent SDS2000X Plus

[2N3055]

I measured the noise floor of my SDS2140X plus at the full bandwidth (500 MHz).
At the vertical setting of 1mV/div this is 74uV, which is even better than the spec of 80uV.
But if I set the vertical to 5mV and higher, the floor noise also increases, while the gain decreases. At 10V/div this is even 131mV. See the attached screen dumps.
Can someone explain why this is so?

Siglent is quite conservative with specifications.


Short version?

Noise will be proportion (percentage) of full vertical dynamic range (sensitivity).
Input of the scope consists of  input attenuator, buffer and amplifier block(s) (VGA), ADC driver and ADC, each with it's noise contribution...
Different sensitivities will be achieved with different attenuation/ amplification factor combinations.
For example, attenuator before amplifier will decrease input signal say, 10x, but all other parts after that will keep the same noise. Since we are  at 10x larger range, noise goes up 10x, input referred.

There are quite a few combinations being used between all the available ranges so noise will sometimes be different than predicted if we had few simple attenuator /fixed gain blocks.

[mathstudi]

Siglent STB3 Demo Board issue (I2C Serial Protocol)

Hi,

According to the manual a 12 bytes frame should be output. But on my Siglent SDS2354X Plus I see only the last 6 bytes, NT_XX_XX_XX_XX. I also made a comparison with a Saleae Logic Analyzer. Also here the same result. Only the last 6 bytes are displayed.

Is there a setting which I have overlooked? 

Cheers

[tautech]

Siglent STB3 Demo Board issue (I2C Serial Protocol)

Hi,

According to the manual a 12 bytes frame should be output. But on my Siglent SDS2354X Plus I see only the last 6 bytes, NT_XX_XX_XX_XX. I also made a comparison with a Saleae Logic Analyzer. Also here the same result. Only the last 6 bytes are displayed.

Is there a setting which I have overlooked? 

Cheers

Maybe.

Screenshot ?

Quick example from SDS1204X HD....

[Martin72]

I²C bus is something I never managed to display in all the years with all scopes.
So with the STB-3, with the Batronix board it worked immediately - on all scopes..
Despite advanced time here, I had just tried again, on the 1104X-E and on the 2504X HD, no chance.
Please show where on the board you pick up the signals.

[tautech]

I²C bus is something I never managed to display in all the years with all scopes.
So with the STB-3, with the Batronix board it worked immediately - on all scopes..
Despite advanced time here, I had just tried again, on the 1104X-E and on the 2504X HD, no chance.
Please show where on the board you pick up the signals.

Use pins marked J23 and J24. 
I2C SDA and I2C SCL.

Don’t forget a reference (gnd) connection especially when powering STB3 from an external supply.

[Martin72]

The question was serious meant my friend. 
Because:
There are not many parameters you can set when decoding I²C.
SDA, SCL, which channel, thresholds, that´s it when you don´t use the serial trigger.
So I determine the channels, set the thresholds to 1.67V each, edge trigger, ASCII....and some BS appears.
I´ve asked for the connection because my signal is not so "wide" as yours when choosing the same horizontal settings like you did.
But on my board j24 and j23 are the same, no print error..

[tautech]

For simple decoding with an Edge trigger you should use a falling edge and always some Holdoff, a little more than one packet length.

[Martin72]

Holdoff makes sense, try it "later".
But it won´t explain the length(are there bitrate settings on the board, like on the batronix?)
But one step after the other, I´ll report.

[tautech]

Holdoff makes sense, try it "later".
But it won´t explain the length(are there bitrate settings on the board, like on the batronix?)
But one step after the other, I´ll report.

Simply, when using an Edge trigger you just won’t get stable triggering without a packet length of holdoff.
Absolute first requirement is to have rock solid stable triggering…….

One must remember what the most powerful feature is of any scope...triggering !

BTW, STB-3 signals are not intended as examples of what a scope can do but they are instead a test the operator knows how to properly use the scope, any scope.
The STB-3 manual provides the basic settings to get results then the rest is up to the knowledge and skill of the operator.

[Martin72]

Instead of a proper description, as others(rigol, batronix) seem to manage, to say that this is something for people who know what they are doing, was not really clever from a marketing point of view.
But we already had that topic.

[tautech]

Instead of a proper description, as others(rigol, batronix) seem to manage, to say that this is something for people who know what they are doing, was not really clever from a marketing point of view.
But we already had that topic.

Marketing what ?
A DSO so smart anyone can drive or one we need be master of ?

STB-3 = test board, a test for not only the scope but the operator also.

[mathstudi]

[/quote]
Maybe.

Screenshot ?

Quick example from SDS1204X HD....
[/quote]

Here are my settings on my SDS2354X Plus. I use SP2035A Probes (10X)
Cheers

[mathstudi]

I²C bus is something I never managed to display in all the years with all scopes.
So with the STB-3, with the Batronix board it worked immediately - on all scopes..
Despite advanced time here, I had just tried again, on the 1104X-E and on the 2504X HD, no chance.
Please show where on the board you pick up the signals.

SCL on J24 -> CH1
SDA on J23 -> CH2

Cheers

[mathstudi]

With the BATRONIX MSO I2C Demo I got this result

[mathstudi]

Instead of a proper description, as others(rigol, batronix) seem to manage, to say that this is something for people who know what they are doing, was not really clever from a marketing point of view.
But we already had that topic.

Marketing what ?
A DSO so smart anyone can drive or one we need be master of ?

STB-3 = test board, a test for not only the scope but the operator also.

In my case, especially the operator 

[tautech]

Here are my settings on my SDS2354X Plus. I use SP2035A Probes (10X)

Compare with this:



I suggest you go back to basics with a falling edge trigger and a packet width+ of holdoff.

With the BATRONIX board there is is virtually zero payload beyond the packet header.
STB-3 packet header is always SIGLENT plus the ever-changing payload where you need the serial triggering to trigger on a those bits.
Get stable triggering for the packet header decode then experiment with the serial trigger to trigger on payload bits.

[mathstudi]

Here are my settings on my SDS2354X Plus. I use SP2035A Probes (10X)

Compare with this:



I suggest you go back to basics with a falling edge trigger and a packet width+ of holdoff.

With the BATRONIX board there is is virtually zero payload beyond the packet header.
STB-3 packet header is always SIGLENT plus the ever-changing payload where you need the serial triggering to trigger on a those bits.
Get stable triggering for the packet header decode then experiment with the serial trigger to trigger on payload bits.

I have selected various holdoff events, but with no success.

[mathstudi]

With the Saleae Logic Analyzer, the same behavior is seen.

SPI protocol, however, is displayed correctly.

Cheers

[Martin72]

@Rob:

Just show us screenshots of your settings please - I tried it again, I even got "rockstable" trigger...But it´s the same like mathstudi´s results.

[tautech]

I have selected various holdoff events, but with no success.

As expected, there many more trigger events in a packet CLK waveform.

You can see the packet width in units of time so instead use time and NOT events for the Holdoff period.

[tautech]

Simple decode trigger holdoff tutorial.

Despite all the magnificent features the modern DSO offers its most powerful tool is the trigger featureset and it need be mastered to use any DSO to its full capability.
For decode use we must inhibit triggering with some holdoff so to NOT have retriggering within a data packet.

Therefore we need identify packet length (time) and apply just enough holdoff to disable the trigger for a defined period.
We can easy press Stop and use the graticules to determine packet length then transfer that time to the trigger holdoff setting as is done in the first screenshot.....with the additional press of the correct unit, in this case m for ms.

All that remains is to set the correct decode configuration and hey presto, a correct and valid decode.

This remains my MO for any initial decode work so to know for sure basic decode works before attempting to use a serial trigger to trigger on any specific bit.

[Martin72]

Just tell the holdoff time you use for I2C, thank you.
Btw., when you set the thresholds for the signals right, it doesn't matter if you have a stable trigger set.
At least on the spi signal from the siglent board.

[tautech]

Just tell the holdoff time you use for I2C, thank you.

Like with any protocol, just a little more that one packet. I2C, 2ms IIRC
Press Stop and measure like I did above.....just eyeball the graticules. 

Btw., when you set the thresholds for the signals right, it doesn't matter if you have a stable trigger set.

Trigger is for stable waveforms, thresholds are for correct decode.
Each need be set correctly.

It is easy and every screenshot I've posted took barely 1 minute to capture from normal scope settings...
Set trigger to falling edge, assess packet width and set holdoff, decode type, assign the clk and data channels and finally other settings....faster than typing this.

[pascal_sweden]

Where is the "D=" for the letter "G"? Is it because "G" is too wide to still fit the "D=" on the screen?

[Martin72]

@Rob:
I know that all, the reason why I want you to show your settings (trigger) is, that I think the Signal is just not the same as on your testboard.
At the moment I have the board at work, test the I2C with two another scopes, in summary with four different scopes and just can't get the same result.
Every other decoding signal is no problem.
I made a short video from the SDS2104X+ to show that I had a stable signal, uploading it when back at home.