Fabio Fumi / Mbed 2 deprecated Speaker_test

Basic speaker testing on a STM32L053R8 board. Based on other examples and improved using commands sent from PC over serial-USB (t=Tone, s=Sweep, p=Police, h=Song, space=Exit). A small 8-Ohm speaker directly plugged on GND/PA_0 (PWM out) makes a low but clearly audible sound.

Dependencies:   mbed

Files at this revision

API Documentation at this revision

Revision 1:7fdec2560f78, committed 2015-01-09

Comitter:
ffxx68
Date:
Fri Jan 09 18:00:42 2015 +0000
Parent:
0:59717cf94c6a
Commit message:
fixed

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/main.cpp	Fri Jan 09 17:46:14 2015 +0000
+++ b/main.cpp	Fri Jan 09 18:00:42 2015 +0000
@@ -50,10 +50,9 @@
            pc.printf ("Tone...\n");
            // generate a short 150Hz tone using PWM hardware output
            // something like this can be used for a button click effect for feedback
-           speaker =0.25; //25% duty cycle - mid range volume
            for (i=0; i<10; i++) {
               speaker.period(1.0/150.0); // 500hz period
-
+              speaker =0.25; //25% duty cycle - mid range volume
               wait(.02);
            }
            speaker=0.0; // off
@@ -62,9 +61,9 @@
            case 's':
            pc.printf ("Sweep...\n");
            // sweep up in frequency by changing the PWM period
-           speaker=0.25;
            for (i=0; i<8000; i=i+100) {
               speaker.period(1.0/float(i));
+              speaker=0.25;
               wait(.02);
            }
            speaker=0.0; // off
@@ -74,7 +73,7 @@
            pc.printf ("Police...\n");
            // two tone police siren effect - two periods or two frequencies
            // increase volume - by changing the PWM duty cycle
-           for (i=0; i<26; i=i+2) {
+           for (i=0; i<10; i=i+2) {
               speaker.period(1.0/969.0);
               speaker = float(i)/50.0;
               wait(.5);
@@ -85,10 +84,10 @@
            break;
            
            case 'h':
-           // Play "happy birthday"
-           speaker=0.25;
+           pc.printf ("Happy birthday...\n");
            for (int i=0;i<=24;i++) {
                speaker.period(1.0/notes[i]);
+               speaker=0.25;
                wait(0.8*intervals[i]/10);
            }
            speaker=0.0; // off