Page 241 - ARM Based Microcontroller Projects Using MBED

8.29 PROJECT 24—SAWTOOTH WAVEFORM 227
BEGIN
Configure DAC port PA_4 as analog output
DO FOREVER
Send 10 steps to DAC port with 2ms each
ENDDO
END
FIG. 8.98 Program PDL.

8.29.4 The PDL

Fig. 8.98 shows the PDL of the program.

8.29.5 Program Listing

The program listing (program: Sawtooth) is shown in Fig. 8.99. At the beginning of the
program, variable aout is configured as analog output and is assigned to DAC port PA_4.

/*************************************************************************
GENERATE SAWTOOTH WAVEFORM
==========================

This program generates a sawtooth waveform with 10 rising steps where
each step width is 2ms. i.e. the period of the waveform is 20ms.
Author: Dogan Ibrahim
Date : August 2018
File : Sawtooth
**************************************************************************/
#include "mbed.h"
Serial MyPC(USBTX, USBRX);
AnalogOut aout(PA_4);
int main()
{
float k;

while(1) // Do forever
{
for(k = 0.0f; k < 1.0f; k = k + 0.1f) // Do 10 times
{
aout = k; // Analog out
wait(0.002); // Wait 2ms
}
}
}
FIG. 8.99 Program listing.