DEMO Help

DASE Quick Start

The following steps define the creation and use of any DASE simulation.

·        Create Functional Blocks

·        Interconnect Blocks

·        Set Block Parameters

·        Run

A Simple Example will Introduce You to the Ease of Using DASE

A low-pass-filter acting on a squarewave:

Step 1: Create Functional Blocks

1.        Launch DASE. There will be three windows created during launch. The top window will be the simulation editor wherein you will build a block diagram of the simulation. (Menu options change depending on which window is being used.)

2.        Create a Square-Wave Function. Pull down the Blocks|Sources menu. In the dialog box select the Function Generator from the Blocks Type listbox. Click the Right Flow button.

3.        Create a Low-Pass-Filter Function. In the Block Libraries listbox of the dialog-box, scroll up to the Communications listing and select it.  In Blocks Type listbox, select  the Low-Pass Filter block and click the Right Flow button.

4.        Create an Oscilloscope Function. In the Block Libraries listbox of the dialog-box, scroll down to the Tools listing and select it.  In Blocks Type listbox, select  the Oscilloscope block and click the Top Flow button. Click the Done button in the dialog box.

Step 2: Interconnect Blocks

1.        Position the Blocks. At this point, the three blocks you have created will be located in the upper left-hand corner of the editor window. Place the mouse cursor over the Function Generator block roughly in the center of the block. (If the cursor changes into a crosshairs, you are over one of the block’s input or output ports and you must move the mouse or you will begin drawing an inter-connect in the next step.

Press the left mouse button and drag the Function Generator  block to the center-left of the window. Release the left mouse button. Repeat this procedure to move the Low-Pass Filter block to the right of the function generator. Finally, use the same method to place the Oscilloscope block below the other two blocks.

2.        Connect the Blocks. Place the cursor over the output port (right side) of the Function Generator block. You will be over the port when the cursor changes into a crosshairs. Press the left mouse button and drag the mouse into the input port (left side) of the Low-Pass Filter block. When the cursor changes into the crosshairs again in response to being over the input port, release the left mouse button. (You may create interconnects with multiple segments by releasing and then re-pressing the left mouse button before moving the mouse along the path of each new segment. An interconnect may not have more than 12 segments.) Place the cursor over the output port of the Low-Pass Filter block.. Press the left mouse button and drag the mouse to the left and arbitrary distance. Release the left button and then press it again. Move the mouse towards the Oscilloscope block. (You may create paths with right angles for neatness or use arbitrary angles.) Create path segments moving towards the Oscilloscope block until your enter channel 1 of the Oscilloscope block. Release the left mouse button. (If you find the interconnect path you are creating is undesirable, you may delete an incomplet path using the Mode|Delete Incomplete Connection menu option.)  

Draw another path from the function generator output into the oscilloscope channel 2.

Step 3: Set Block Parameters

1.        Configure the Function Generator. Place the cursor over the function generator block and click the right mouse button to create the block’s speed menu. Select the Attributes menu item and the function generator dialog box will appear.

Set the function generator to output a squarewave by selecting the square radio button in the mode group box. Set the frequency control to internal by selecting the INT radio button in the Freq group box and enter a value of 2400 in the edit box next to the radio button.

Since the squarewave mode requires a duty-cycle setting, enter a value of 50 in the % edit box and select the INT radio button in the Duty Cycle group box.

Finally, enter a value of 1 in the Amplitude edit box. Click OK.

2.       Configure the Low-Pass Filter. Bring up the attributes box for the low-pass filter in the same manner used for the function generator. Select a Butterworth response using the pull-down list box. Next, enter 1800 in the corner frequency edit box.. Finally set the number of poles to 4 using the pull-down  list box. Click OK.

3.       Configure the Oscilloscope.  Pull down the oscilloscope dialog box in the manner used for the previous blocks. In the edit box for naming channel 1 enter “filtered data” . For channel 2 enter “unfiltered data”. Click OK.

Right click the oscilloscope block and select Display from the speed menu. This will open the display window for the oscilloscope tool. Change the mode settings for channels 1 and 2 to DC. Using the vertical scroll bars for channel 1, position the green cursor on the far left of the scope screen 1 major division above the centerline. Repeat this for channel 2 but place the red cursor 1 major division below centerline.

Locate the mode-control push button left of the start-time edit box and click it through the modes until it reads NORMAL. Select Channel 1 as the trigger source using the radio button for channel 1, enter a value of 0.5 in the trigger level edit box and select the positive slope radio button. As currently configured, the oscilloscope will behave just like a laboratory oscilloscope and trigger when the signal on channel 1 rises past 0.5.

Finally, scroll the time/div list box down until a value of 2 mS is displayed.  (Note you will not be able to select a smaller time/div setting at this point because you have not set the sample rate fast enough. The sample rate will be set correctly later.)

Step 4: Run the Simulation

1.       Set the Desired Sample Rate. You may set the simulation sample rate in the Run Status Window or by selecting the Simulation|Sample Parameters… menu item. If you choose the former, enter a value of 24000 in the Sample Rate edit box of the Run Staus window. If you chose the menu approach, enter this same value in the sample rate edit box of the Simulation Control Parameters dialog box and close the dialog box. Now return to the oscilloscope window and scroll the time/div list box to 200 mS.

2.       Prepare the Simulation Display.  Before running the simulation it is often a good idea to orient the various windows to present the progress in a meaningful manner. For this simple example, size the Run Status window so only the status box and the control buttons are visible and move the window to the lower left of the DASE display. Next, size the oscilloscope window as desired and move it to the upper right. (You will notice as you size the oscilloscope window, the graticle size adjusts to maintain the relative proportions of the horizontal and vertical axes.)

3.       Run the Simulation. Click the RUN button in the Run Status window. You will note the oscilloscope displays a single sweep and stops while the simulation continues to run. This is due to the small signal out of the filter only exceeding 0.5 once. Click the STOP button in the Run Status window and release the run’s data by selecting the Data|Release Data… menu item or hitting the F9 key.

Open the Function Generator attributes dialog box by double clicking on the icon for the block and change the frequency to 1200 Hz. Close the dialog  box and click the RUN button in the Run Status window. Note the oscilloscope triggers continuously now because the filter output regularly exceeds 0.5.

Play with the filter bandwidth settings and the frequency of the squarewave to study the effects on the filter output signal.

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