avnish aggarwal / Mbed 2 deprecated Book-PE_09-10_Metronomexx

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Dependencies:   mbed

Fork of Book-PE_09-10_Metronomex by avnish aggarwal

main.cpp@0:d7c850cdbc39, 2013-05-24 (annotated)

Committer:
robt
Date:
Fri May 24 21:49:35 2013 +0000
Revision:
0:d7c850cdbc39
Child:
1:733a0de4d34c
by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Who changed what in which revision?

UserRevisionLine numberNew contents of line
robt 0:d7c850cdbc39 1 /*Program Example 9.10: Metronome. Uses Ticker to set beat rate
robt 0:d7c850cdbc39 2 */
robt 0:d7c850cdbc39 3 #include "mbed.h"
robt 0:d7c850cdbc39 4 #include <stdio.h>
robt 0:d7c850cdbc39 5 Serial pc(USBTX, USBRX);
robt 0:d7c850cdbc39 6 DigitalIn up_button(p5);
robt 0:d7c850cdbc39 7 DigitalIn down_button(p6);
robt 0:d7c850cdbc39 8 DigitalOut redled(p19); //displays the metronome beat
robt 0:d7c850cdbc39 9 Ticker beat_rate; //define a Ticker, with name “beat_rate”
robt 0:d7c850cdbc39 10 void beat(void);
robt 0:d7c850cdbc39 11 float period (0.5); //metronome period in seconds, inital value 0.5
robt 0:d7c850cdbc39 12 int rate (120); //metronome rate, initial value 120
robt 0:d7c850cdbc39 13
robt 0:d7c850cdbc39 14 int main() {
robt 0:d7c850cdbc39 15 pc.printf("\r\n");
robt 0:d7c850cdbc39 16 pc.printf("mbed metronome!\r\n");
robt 0:d7c850cdbc39 17 pc.printf("_______________\r\n");
robt 0:d7c850cdbc39 18 period = 1;
robt 0:d7c850cdbc39 19 redled = 1; //diagnostic
robt 0:d7c850cdbc39 20 wait(.1);
robt 0:d7c850cdbc39 21 redled = 0;
robt 0:d7c850cdbc39 22 beat_rate.attach(&beat, period); //initialises the beat rate
robt 0:d7c850cdbc39 23 //main loop checks buttons, updates rates and displays
robt 0:d7c850cdbc39 24 while(1){
robt 0:d7c850cdbc39 25 if (up_button ==1) //increase rate by 4
robt 0:d7c850cdbc39 26 rate = rate + 4;
robt 0:d7c850cdbc39 27 if (down_button ==1) //decrease rate by 4
robt 0:d7c850cdbc39 28 rate = rate - 4;
robt 0:d7c850cdbc39 29 if (rate > 208) //limit the maximum beat rate to 208
robt 0:d7c850cdbc39 30 rate = 208;
robt 0:d7c850cdbc39 31 if (rate < 40) //limit the minimum beat rate to 40
robt 0:d7c850cdbc39 32 rate = 40;
robt 0:d7c850cdbc39 33 period = 60/rate; //calculate the beat period
robt 0:d7c850cdbc39 34 pc.printf("metronome rate is %i\r", rate);
robt 0:d7c850cdbc39 35 //pc.printf("metronome period is %f\r\n", period); //optional check
robt 0:d7c850cdbc39 36 wait (0.5);
robt 0:d7c850cdbc39 37 }
robt 0:d7c850cdbc39 38 }
robt 0:d7c850cdbc39 39
robt 0:d7c850cdbc39 40 void beat() { //this is the metronome beat
robt 0:d7c850cdbc39 41 beat_rate.attach(&beat, period); //update beat rate at this moment
robt 0:d7c850cdbc39 42 redled = 1;
robt 0:d7c850cdbc39 43 wait(.1);
robt 0:d7c850cdbc39 44 redled = 0;
robt 0:d7c850cdbc39 45 }
robt 0:d7c850cdbc39 46