External Triggering

The Analog Discovery 2 is an all-in-one pocket instrument for electronics containing a 2-channel oscilloscope, power supplies, waveform generators, logic analyzers, and more to measure and generate analog and digital signals. The tools can be manually started or can be triggered by an external source.


Inventory

Prerequisites

  • Familiarity with navigating the WaveForms GUI and switching between different tools. See the “Take a measurement” section of the Getting Started Guide for your OS.

Step 1: Set up the Circuit

This tutorial triggers an oscilloscope acquisition triggered through an external push button via WaveForms. A picture of the circuit and a schematic of the two circuit portions are provided below.

Fritzing circuit Schematic image


Step 2: Set up the Software

Open the WaveForms software and connect to the instrumentation module, e.g. the Analog Discovery 2.

Click on the Waveform Generator icon to open the Arbitrary WaveForm Generator.

The WaveForm Generator can be left with the default settings of a 1 kHz sine wave with a 1 V amplitude.

Go back to the Welcome tab of the WaveForms software and click on the oscilloscope icon to open up the oscilloscope.

Click on the green down button in the upper right hand corner of the GUI to expand the available options.

The Trigger type drop down menu controls the type of trigger used. The default value is “Auto”. Change this value to “Normal”.

The Trigger source drop down menu controls what source is used for the trigger. The default value is “Channel 1”. Change this value to “External 1”.

Go back to the Welcome tab of the WaveForms software and click on the Power Supplies icon to open up the Power Supplies.

Disable the Negative Power Supply by clicking on the button labeled “Negative Supply (V-) On” to switch it off. Leave the Positive Power Supply enabled but change the voltage supplied to 3.3V by *clicking* on the corresponding dropdown menu on the right-hand side of the GUI.


Step 3: Trigger the Tools

Click the Master Enable button on the Power Supply tool.

Go to the WaveForm Generator tab and click on any green “play” arrow to start the WaveForm Generator.

Go to the oscilloscope tab and click on any green “play” arrow to start the oscilloscope acquisition.

Note that the WaveForm generator will be “Armed” as the external trigger has not been activated.

Press the external push button to trigger an oscilloscope data acquisition.

The oscilloscope tab on the WaveForms GUI will show as “Trig'd” and then “Armed” to indicate that the trigger has been rearmed. The display will show one full data acquisition whose length is dictated by the time base. With a time base of 1 ms/div, 10 ms of data will be obtained per acquisition.


Further questions about using external triggers with the Analog Discovery 2 and the WaveForms software can be posted on the Digilent Forum.