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8.32 PROJECT 27—ARBITRARY PERIODIC WAVEFORM 233

FIG. 8.107 The generated waveform.

8.31.5 Program Listing

The program listing (program: SineWave)isshown in Fig. 8.106. At the beginning
of the program, variable aout is configured as analog output and is assigned to DAC
port PA_4. The program consists of an endless loop. Inside this loop, a for loop is used
which iterates 100 times with step size of 100 μs. Therefore, the period of the generated
waveform is 100 100μs¼10ms. The amplitude of the waveform is shifted up so that it is
always positive. The maximum and minimum values of the sin function are 1. There-
fore, 0.5 1 takes values between 0 and 1, that is, the amplitude of the generated wave-
form is between 0 and +3.3V. Fig. 8.107 shows the generated sine waveform. In this
figure, the vertical axis is 1V/division and the horizontal axis is 5ms/division.

8.32 PROJECT 27—ARBITRARY PERIODIC WAVEFORM

8.32.1 Description
In this project, we generate an arbitrary periodic waveform with a period of 20ms where
the details of the waveform are as shown in Fig. 8.108.