Page 236 - ARM Based Microcontroller Projects Using MBED

222 8. INTERMEDIATE LEVEL PROJECTS

/*************************************************************************

SOUND LEVEL METER
=================
This is a sound level meter project. An electret microphone with an
amplifier is connected to analog input PA_0 of the develomet board.
The peak-to-peak output voltage of the amplifie is measured and is
displayed on the PC screen in millivolts. This reading is proportional
to the ambient sound level and needs to be calibrated in dB.
Author: Dogan Ibrahim
Date : August 2018
File : SoundLevel
**************************************************************************/
#include "mbed.h"

Serial MyPC(USBTX, USBRX);
AnalogIn Sound(PA_0);
Timer tim;
// Clear the screen
//
void clrscr()
{
char clrscr[] = {0x1B, '[', '2' , 'J',0};
MyPC.printf(clrscr);
}

//
// Goto specified line and column
//
void gotoscr(int line, int column)
{
char scr[] = {0x1B, '[', 0x00, ';' ,0x00, 'H', 0};
scr[2] = line;
scr[4] = column;
MyPC.printf(scr);
}

int main()
{
double mV;
float SMax = 0,Peak,SMin = 4096;

//
// Read the peak-topeak output voltage of the audio amplifier,
// then display the voltage on the PC screen
//
while(1) // Do forever

FIG. 8.93 Program listing.
(Continued)