Analog Discovery 2 Triggering

[KatharinaSt]

Hi guys,

I am using the analog discovery 2 and I want to generate a triggered Waveform. Additionally I am using the Software Waveforms.
Is there a possibility to trigger the waveform generator of the analog discovery with an external trigger within the Software Waveforms?

If not, is it possible with the pydwf package in Python? If yes, can you provide me with some example code?

 

Additionally I wanted to ask if it is possible to generate a biphasic square waveform with the analog discovery 2?

 

BR, Katharina

[jruff]

In waveforms, the wavegen module is able to produce a waveform that is triggered by changing from no synchronization to independent or synchronized. You can then adjust the source of the trigger and other conditions regarding it. This can also be done via the software.

You can then change the type of signal output by the wavegen to produce a custom waveform where you will be able to manually control the samples.

[JColvin]

Hi @KatharinaSt,

Once you set up a triggered waveform by changing to Independent or synchronized as @jruff indicated, you can then create the biphasic square wave by setting the run time to be equal to the period of your square wave. The length in-between each 'pulse' can then be adjusted by changing the Wait time. If you only want it to occur a set number of times, change the Repeat option off of Infinite to whatever value you need.

Let me know if you have any questions.

Thanks,
JColvin

[KatharinaSt]

Thank you very much for the answer. One other question:

Is there a possibility to start the waveform at the rising edge of the trigger and to stop at the falling edge?

BR, Katharina

[KatharinaSt]

@JColvin I tried to trigger according your instruction but it is not working...

[JColvin]

Hi @KatharinaSt,

You can only start the Wavegen with a trigger condition; it is not possible (at least as far as I am aware) to stop the generation based on separate trigger. If you set up your desired waveform to only run for a set amount of time before repeating, if the trigger condition, such as the Logic Analyzer instrument running, is no longer present, the Wavegen Instrument will stop once it reaches the end of the run time for that particular 'cycle'.

With regards to getting the Wavegen generation to start on a trigger, I suspect the issue is that you did not start the Wavegen instrument so that it could arm itself and properly wait for the trigger condition.

If this is not the issue you are running into, please let me know with some more detail what is not working for you.

Thanks,
JColvin

 

[KatharinaSt]

HI @JColvin,

I started the wavegen instrument so that it could arm, but there is no signal showing up. My input at the trigger 1 is a analog input pulse from another device, which changes between 0 and 1 (1sec high, 4sec low). Now, the wavegenerator 1 should trigger according the rising edge of the trigger 1, but there is no signal showing up, when I connect an oscilloscope at the wavegenerator 1. But I don't know why... 

 

Thank,

Katharina

[JColvin]

Hi @KatharinaSt,

To make sure I understand correctly, you say there is no signal showing up, even if you only connect one of the oscilloscope channels of the Analog Discovery 2 to the external trigger signal source? I would try to check this setting up a Normal trigger on oscilloscope Channel 1 that looks for a Rising Edge trigger that exceeds 500 mV, and then push the Single button on the upper left to have the Oscilloscope arm itself and wait for that first rising edge condition to confirm that the external system is producing the trigger.

Other things that I would do to debug this is if the Analog Discovery and the external system share the same ground and what voltage level your external trigger is producing. By default, the Analog Discovery 2 runs at 3.3 V CMOS logic so it would not trigger on a 1 V pulse for example.

I've attached a workspace of my example setup testing this (made for the Analog Discovery 3, but it will also run on the Analog Discovery 2 as is) where I have a one second long pulse after 4 seconds of waiting be generated twice on one of the Wavegen channels; that signal is connected to both Trigger 1 and Scope 1 on a breadboard.

I then have the Logic Analyzer (connected to nothing) only run with Trigger 1 being active/detected.

Wavegen Channel 2 is only triggered when the Logic Analyzer is active and creates a 10 Hz sine wave that runs for 1.5 seconds. This channel is externally connected to the Scope 2 wire.

With the Oscilloscope continually running in Shift/Scan mode and both the Logic and Wavegen channel 2 armed, I got the following screenshot after having Wavegen channel 1 run a couple of different times.

Let me know if you have any questions.

Thanks,
JColvin

delayed-trigger-multi-instrument-example.dwf3work

[KatharinaSt]

Hi @JColvin,

 

when I use the following settings:

..., which is the correct waveform, cause I want a break between the pulses, I get the following result:

The pulse above is my trigger and the one below is the result of my wavegenerator. It gives me only one biphasic pulse, but I want the waveform as above (several biphasic pulses with a short break inbetween. This wave should run for 2 sec and should then stop and wait for the next rising edge.

If I choose the following settings:

... I get the correct duration of the biphasic pulses, but not the breaks between the pulses:

 

Is there a possibility to get the waveform from the second picture for 2 seconds in a row ?

 

BR, Katharina

[JColvin]

Hi @KatharinaSt,

I'm not readily able to produce the scenario you are wanting to create; I get the same single biphasic "pulse" on the trigger, but can't readily get it to repeat itself with the same delay between pulses during the trigger condition.

The creator of the WaveForms software @attila might have some additional ideas on how get this style of waveform output to work, but it may be awhile before we get a response from him depending on his scheduled vacation over the holiday timeframe.

Thanks,
JColvin

[attila]

Hi @KatharinaSt

Create a custom waveform (Type/Cog/New) like this, Frequency 1.5ms, Run: 2s (pic1)
The repeat Trigger option (the last checkbox) selects to rearm for each Wait-Run cycle, or unchecked will only arm initially, once triggered repeat Wait-Run the specified number of times without rearming. (pic2)