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Logic Detector as trigger in Scope. Is it possible?

m72

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m72

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Hello!

Can be "Logic Detector" added to trigger menu in "Scope" instrument?
I use this workaround in WaveForms V3.11.7 (beta, Windows, 64 bit):
1. In AD2 settings set "Trigger 1" to "Logic Detector"
2. In "Scope" use "Trigger 1" as trigger.

With best regards, Mikhail.

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attila Prolific Poster

attila

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Hi @m72

This may look like a digital issue, from ADC to FPGA... but i don't it is since we should see similar glitch on the upper side too.

Could you provide detail about the experiment?
I see you have set 10x probe... Are you using (single ended) BNC probe at 10x ?

In case you are using differential input with high common mode voltage, the signal might enter in limitation or clamping starts to act, which also depends on the offset:
https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/reference-manual?redirect=1#scope_driver
https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/reference-manual?redirect=1#scope_signal_scaling

The highlighted "noise band" indicates high frequency signals (noise, glitch), above current sampling rate, which indicates some analog issue:

image.thumb.png.d0e9c276f6fa3ce717918177555188e3.png

 

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m72 Frequent Visitor

m72

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Hello!

Very very strange. It occurs without any scheme and on different PCs. Only shift level on the screen changes.

Conditions:
Attenuation 9X...100X & offset -16V ...-24V
May be this is an calibration effect?
Or it is damaged by high voltage impulse... At zero state second channel on this AD2 is more noisy than first.

With best regards, Mikhail.
P.S.
I often find bugs. Even in such things as TV set, PLC (in Siemens LOGO! One is definitely there), Atmega, etc.

 

210321ABEEA0.dwf3calib

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attila Prolific Poster

attila

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Hi @m72

You have in private message a software version which changes a bit the digital timings.
Please install this, reconnect the device to make sure it will get reconfigured and start the application. Let me know if this solves the issue.

The scope inputs are rated for up to +/-50V, but it should survive higher voltages due the 820k series resistor before the 7.5-20mA protection.
High voltages (with energy) usually damage the gain selector analog switch, which leads to DC reading.
https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/reference-manual#scope_input_divider_and_gain_selection

The attenuation option is intended to scale the scope readings, it is not a device feature. For instance when you use a 10x scope probe (9M series), the scope input will actually get 1/10 of voltage. Specifying 10x attenuation the software will multiply the readings by 10, to compensate this. You can also use this to reflect external voltage dividers, amplifiers...

Edit:
The calibration adjust the amplitude and offset.

Edited by attila
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m72 Frequent Visitor

m72

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Hello!

Just tested it with simplest settings (attenuation 1X, 50 ns/div, zero signal). Only offset on the screen is changed.
Scope1 ... Scope3.
1. It happens only with second channel.
2. When offset is [-2.34V ... -1.76V].
3. At the borders noise is like a rare peaks. At the center like as an ADC input is overloaded.
4. Peaks values are -7.6V & +7.6V.

Scope4.
1. Offset -4V
2. But signal is not zero, it is +2V. So it became to the same "- div from the center". Peaks are -5.6V & + 9.6V -> shifted +2.0V.

1V/div, 2V/div, 5V/div - the same situation.

Why I am so cycled about calibration.
Scope1 LG offset is -0.325 V. 
Scope1 HG offset is -0.0296 V.
Scope2 LG offset is -0.300 V. 
Scope2 HG offset is -0.0274 V.
So signal -2V can be on the edge between "Low Gain" & "High Gain". But because offset is quite big (15% of ADC input, may be damaged?), algorithm can not choose the right gain and generates peaks on switching.
By this theory lowest border of the noise is -2.35 V - 0.3 V = - 2.65 V. If signal lower then this it works fine with "Low Gain". A bit upper there is "gray, turbulent zone". And greater than -1.76V the stable zone of "High Gain". 

With best regards, Mikhail.

45.png

 

peaks.dwf3work

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m72 Frequent Visitor

m72

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Hello!

Digital Discovery, WaveForms from 3.11.18, Windows 7 x64.

When allow "Logic Analyzer" from "Protocol" by default it change DIO24 -> DIN0 (mode 800 MHZ, DIO0..7).
If start "Logic Analyzer" at "200 MHz, DIN0...DIN23, DIO24...DIO31" it change sample rate "100...400MHz" -> "800 MHz" and change DIO24 -> DIN0. 
If start "Logic Analyzer" at "400 MHz, DIO24...DIO39" it change sample rate "100...400MHz" -> "800 MHz" and make DIO >= 32 "not available". 
And after that "800 MHz" -> "400 MHz" moves DIO32 -> DIO24 and DIO33 also to DIO24.

With best regards, Mikhail.

34.png

35.png

36.png

Edited by m72
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attila Prolific Poster

attila

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Hi @m72

This looks like a digital issue in the ADC.
Have you used for this tests the WF v3.11.23 I sent you in private message?

On 9/13/2019 at 7:07 PM, m72 said:

Hello!

Just tested it with simplest settings (attenuation 1X, 50 ns/div, zero signal). Only offset on the screen is changed.
Scope1 ... Scope3.
1. It happens only with second channel.
2. When offset is [-2.34V ... -1.76V].
3. At the borders noise is like a rare peaks. At the center like as an ADC input is overloaded.
4. Peaks values are -7.6V & +7.6V.

 

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attila Prolific Poster

attila

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Hi @m72

After adding the Order option in Logic Analyzer (splitting the Input selection in two) I have forgotten to update the Protocol/Logic Analyzer to set the Order option automatically.

Thank you for the observation, it is fixed for the next release.

On 9/13/2019 at 7:46 PM, m72 said:

Digital Discovery, WaveForms from 3.11.18, Windows 7 x64.

When allow "Logic Analyzer" from "Protocol" by default it change DIO24 -> DIN0 (mode 800 MHZ, DIO0..7).
If start "Logic Analyzer" at "200 MHz, DIN0...DIN23, DIO24...DIO31" it change sample rate "100...400MHz" -> "800 MHz" and change DIO24 -> DIN0. 
If start "Logic Analyzer" at "400 MHz, DIO24...DIO39" it change sample rate "100...400MHz" -> "800 MHz" and make DIO >= 32 "not available". 
And after that "800 MHz" -> "400 MHz" moves DIO32 -> DIO24 and DIO33 also to DIO24.

 

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m72 Frequent Visitor

m72

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Hello!

WaveForms 3.13.16, Windows 7, x64.

Speed test with Digital Discovery fails. ?
With Analog Discovery works fine. Latency 0.15...0.20 ms, to device 20...25 MBps, from device 29...41 MBps.

Some problems with 125 MHz base frequency in Digital Dicovery after reconnection (for example after failed "speed test") found.
The kernel frequency is set to 125 MHz. Ok!
The "Patterns" tab generates *1.25 faster than required. Clock 1MHz -> 1.25 MHz.
In the "Logic" tab maximum sampling frequency in the list is "800 MHz", but the measurements are right "1.25MHz". 

Work around: after reconnect Digital Discovery it is need to "rechange" base frequency in the "Supplies" tab (step down and step up is enougth).

With best regards, Mikhail.

DD_speed_test.png

Edited by m72
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m72 Frequent Visitor

m72

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Hello!

WF 3.13.18, Windows 7, x64

Under some conditions, the pattern generator produces glitches at the end of the sequence.
I think that in the "Auto" mode the field "Run" should be rounded down.
An example with this effect in attachment. The DIO0 pin is connected to the first channel of the oscilloscope.

With best regards, Mikhail.

glitch.png

glitch.dwf3work

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attila Prolific Poster

attila

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Hi @m72

The source of the problem is that the actual generator rate is not 176kHz but 176,056Hz  (100MHz/568)
For this the run time should be 22.72us (4/(100e6/568))
The WF app in the auto run calculation takes in account the desired rate... I will fix it now

Thank you for the observation.

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m72 Frequent Visitor

m72

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Hello!

I have two devices: AD2 green and AD2 blue (Ni Edition).
The new version of WF (3.16.14 & 3.16.15) does not work with AD2 blue (Part# 750290-01). It says that "Device is not calibrated". And I can not calibrate it at all. The result of calibration can not be saved in device. With AD2 green (Part# 210-321) works fine.
The previous version (3.16.11) works fine with both.

With best regards, Mikhail.

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m72 Frequent Visitor

m72

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Hello!

WF 3.16.24, Windows 7 x64, Digital Discovery

Function Protocol.SPI.Read does not work properly with size equal to power of 2 (started from 16, 32, 64, 128...). I found this workaround. Read 2^n-1 bytes and one extra. Works well up to page_size == 65536.

  

function check_page(addre,addrh,addrl)
{
    var data;
    Protocol.SPI.Start();
    Protocol.SPI.Write(8, [0x03,addre,addrh,addrl]); // 0x03 == read block command
    data = Protocol.SPI.Read(8, page_size - 1); // main read
    data[page_size - 1] = Protocol.SPI.Read(8, 1); // one extra byte
    Protocol.SPI.Stop();
    for (i=0;i<page_size;++i)
        if (data[i]!=0xFF)
            return false;
    return true;
}

 

With best regards, Mikhail.

Edited by m72
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