Lab 7: Control Peripherals
7 - 52 TMS320F2837xD Microcontroller Workshop - Control Peripherals
7. Open a memory browser to view some of the contents of the ADC results buffer. The
address label for the ADC results buffer is AdcBuf (type &AdcBuf) in the “Data” memory
page. We will be running our code in real-time mode, and we will need to have the
memory window continuously refresh.
8. Run the code (real-time mode) using the Script function: Scripts Realtime
Emulation Control Run_Realtime_with_Reset. Watch the window update.
Verify that the ADC result buffer contains the updated values.
9. Open and setup a graph to plot a 50-point window of the ADC results buffer.
Click: Tools Graph Single Time and set the following values:
Acquisition Buffer Size 50
DSP Data Type 16-bit unsigned integer
Sampling Rate (Hz) 50000
Start Address AdcBuf
Display Data Size 50
Time Display Unit
ms
Select OK to save the graph options.
10. The graphical display should show the generated 2 kHz, 25% duty cycle symmetric PWM
waveform. The period of a 2 kHz signal is 500 ms. You can confirm this by measuring the
period of the waveform using the “measurement marker mode” graph feature. Disable
continuous refresh for the graph before taking the measurements. In the graph window
toolbar, left-click on the ruler icon with the red arrow. Note when you hover your mouse
over the icon, it will show “Toggle Measurement Marker Mode”. Move the mouse to
the first measurement position and left-click. Again, left-click on the Toggle
Measurement Marker Mode icon. Move the mouse to the second measurement
position and left-click. The graph will automatically calculate the difference between the
two values taken over a complete waveform period. When done, clear the measurement
points by right-clicking on the graph and select Remove All Measurement Marks.
Then enable continuous refresh for the graph.
Frequency Domain Graphing Feature of Code Composer Studio
11. Code Composer Studio also has the ability to make frequency domain plots. It does this
by using the PC to perform a Fast Fourier Transform (FFT) of the DSP data. Let's make
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