Oscilloscope

An oscilloscope (or “scope”) allows you to view signal voltages, typically in a two-dimensional graph where one or more electrical potential differences (on the vertical axis) are plotted as a function of time or of some other voltage (on the horizontal axis).

Most of the time, oscilloscopes are used to show events that repeat with either no change or change slowly.


1. Menu

See Menu in Common Interfaces.

1.1. View



2. Toolbar

The trigger controls allow you to stabilize repeating waveforms and capture single-shot waveforms.

3. Channels

This toolbar contains the time and channel configuration groups. The toggle button in the top-left edge enables/disables the auto hiding of this toolbar.

Add Channel button opens a drop-down with the following options:

The check-box before the group name enables or disables the respective channel. The properties drop-down button in the top-right corner allows you to configure the channel properties. The mathematic and reference channels also have a close button.

 

3.1. Time Group

Use the time group to position and scale the waveform horizontally using the time base and the horizontal trigger position controls.

 

 

3.2. Real Channels

Use the real channel (vertical controls) to position and scale the waveforms vertically using the offset and range controls for each channel.


Input Coupling

Coupling is the method used to connect an electrical signal from one circuit to another. In this case, the input coupling is the connection from your test circuit to the oscilloscope.

On the Electronics Explorer board, the input coupling AC and DC are separate input connectors on the board with AC and DC marks.
On the Analog Discovery BNC Adapter jumper select between AC and DC coupling.
DC coupling shows all of an input signal. AC coupling blocks the DC component of a signal so that you see the waveform centered at zero volts.

The following diagram illustrates this difference. The AC coupling setting is handy when the entire signal (alternating plus continuous components) is too large for the volts/div setting.

DC coupling AC coupling
2V peak-to-peak sine wave with 2V DC component

3.3. Mathematic Channels

The integrated mathematic functions allow you to perform a variety of mathematical calculations on the input signals of the oscilloscope. Simple and Custom mathematic channels can be added with the “Add Channel” button from the Channels. The simple mathematic channel can be configured to add, subtract, multiply, or divide two channels. The mathematic operations are performed by the PC, so the oscilloscope device cannot trigger on these channels. The units for the math channel can be specified, for instance: A, W.

In the property drop-down, the following can be configured:


Custom Mathematic Channel

The custom or simple mathematic channel can be selected under the channel properties, as shown below.

The Custom Math Function editor can be launched with the bottommost button showing the formula.

You can type the custom function in the Enter Function text box. If the entered function is valid, the resulting number for one sample is displayed, otherwise the error description is listed.

Click Apply to apply changes.

Click OK to save the last valid function.

Click Cancel to use the function saved before the editor was opened.

Accepted values are:


3.4. Reference Channels

The reference channels can be added using the “Add Channel” button from the Channel toolbar.

In the property drop-down, the following can be configured:

4. Main Plot



  1. The center of the display is marked with grid lines. Each vertical and horizontal line constitutes a major division. These are laid out in a 10-by-10 division pattern. The tick marks on the sides between major divisions are called minor divisions. The labeling on the oscilloscope controls (volts/div and sec/div) always refer to major divisions.
  2. On the left side of the view, the horizontal voltage grid line marks are shown for the active channel. Left-mouse dragging changes the offset and right-dragging adjusts the range of the active channel.
  3. The time marks of the vertical grid lines are located at the bottom. Left-mouse dragging changes the time (trigger horizontal) position and right-dragging adjusts the time base.
  4. On the right side of the view, left-mouse dragging changes the vertical trigger level and right-dragging adjusts the hysteresis level.
  5. The channel list colors make channel identification easy. Left-mouse click a rectangle activates the channel. Right-mouse click disables/hides it.
  6. The status label shows the state of the oscilloscope. See Acquisition States for more information.
  7. The horizontal trigger position arrow can be dragged with the mouse.
  8. The zero point arrows for each channel can be dragged with the mouse to change the vertical position (offset).
  9. The vertical trigger position arrow can be dragged with the mouse to change the trigger level. The two smaller arrows represent the low and high levels (hysteresis).
  10. The drop-down button (in the top-right corner or mouse right-click) contains options for:

 

4.1. Digital Channels

The Logic Analyzer can be enabled inside the Oscilloscope interface by adding digital channels, or by enabling from the view menu.

The picture below shows the analog output of a binary counter on a Pmod-R2R.

 

5. Views

5.1. XY

Using the XY view allows you to plot one channel against another. This plot could be the I-V curve of a component such as a capacitor, inductor, or diode, or a Lissajous figure showing the phase difference between two periodic waveforms. XY view is also capable of more advanced operations, such as plotting a math channel against a reference waveform.

The properties button in the top-left corner opens a drop-down to select the channels for X and Y representation.


5.2. Histogram

A histogram is a graphical representation of the voltage distribution in a signal waveform. It plots the distribution of values for each voltage value, with the number of times the signal has a certain voltage value represented as a percentage.

The picture below shows the histogram view of a sine and another signal.

The properties button in the top-left corner or mouse right-click opens a drop-down to select scaling.


5.3. Data

The Data view displays the acquisition samples and the time stamps.


The first column shows the sample index, the second shows the time stamp followed by the values for channels.

The selected cells can be copied and pasted to other applications.

 

5.4. Measurements

The Measurements view shows the list of the selected measurements. The first column in the list shows the channel, the second shows the type, and the third shows the measurement result. At the top are Add and Remove buttons and up and down buttons to change the order of the measurements in the list.

Pressing the Add button opens the Add Measurements window. On the left side is the channel list, and on the right side is a tree view containing the measurement types in groups. Below it is the current value of the measurement and a short description. Pressing the Add button here (or double-clicking an item) adds it to the measurement list.



Vertical-axis measurements for each channel:

 

5.5. Logging

See Logging in Common Interfaces.

 

6. Export

See Export in Common Interfaces.