Complementary Waveform Generator Example

This page is a step by step example of using the Complementary Waveform Generator.

This example uses the Numerically Controller Oscillator (NCO) Output signal (running at 50% duty cycle) as the input and the High Frequency Internal Oscillator (HFINTOSC) as clock.

This example also produces two complementary outputs and uses an external switch as the shutdown control as shown in the block diagram below.

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CWG Example Setup

1

The NCO is selected as the input for the CWG.

exp2.png
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2

The High Frequency Internal Oscillator is selected as the clock source.

exp3.png
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3

Dead Band delays are set to 63-64 clock counts.

exp4.png
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4

The CWGFLT1 pin is enabled as a shutdown signal which is connected to a normally open momentary switch. When the switch is pressed, a low signal appears on the CWGFLT1 pin and triggers the shutdown.

exp5.png
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5

Auto-restart is enabled and the Shutdown bit is cleared to start in run mode.

exp6.png
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6

Both outputs are set to drive to their respective inactive mode when the shutdown signal occurs.

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7

The CWG outputs are connected to the I/O pins and the output polarity is set to normal mode.

exp8.png
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8

The CWG is then enabled.

For reference the NCO setup code is also shown that produces the input signal.

exp9.png
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CWG Example Operation

The CWG example is running and the screen capture below shows the results.

The NCO signal can be seen at the top of the screen capture along with the CWGA and CWGB signals. You can also see the dead band delays that are triggered by the edges of the NCO input signal.

exp10.png
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The CWG is forced into shutdown mode.

When the momentary switch is pressed, the CWG outputs are driven to their inactive state showing the shutdown has occurred.

exp11.png
Click image to enlarge.

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