Page 249 - ARM Based Microcontroller Projects Using MBED

8.33 PROJECT 28—WAVEFORM GENERATOR 235
BEGIN/MAIN
Configure DAC port PA_4 as analog output
Store waveform voltage samples in array Waveform
DO FOREVER
DO for all sample points
CALL GenerateV(sample)
Wait 1 millisecond
ENDDO
ENDDO
END/MAIN

BEGIN/GenerateV(sample)
Generate voltage at the DAC equivalent to sample
END/GenerateV
FIG. 8.109 Program PDL.

8.32.5 Program Listing

Fig. 8.110 shows the program listing (program: Arbitrary). At the beginning of the pro-
gram, the waveform voltage sample points are stored in a floating point array called Wave-
form. Function GenerateV generates the given voltage at the DAC port. Inside the main
program, the voltage sample points are sent to function GenerateV to generate the required
waveform.
Fig. 8.111 shows the generated waveform. In this figure, the vertical axis is 0.3V/division
and the horizontal axis is 2ms/division.

8.33 PROJECT 28—WAVEFORM GENERATOR

8.33.1 Description
This is a waveform generator program which can generate the following waveforms: fixed
voltage, sawtooth waveform, triangular waveform, sine waveform, and arbitrary waveform.
The parameters of each type of waveform are received from the keyboard.

8.33.2 Aim

The aim of this project is to show how a waveform generator program can be developed.