Peiling Yi / Mbed OS digitalInPolling_modify2

lab2-part1

Fork of digitalInPolling_sample by William Marsh

main.cpp@3:28c7d280790e, 2018-02-01 (annotated)

Committer:
Peilingyi
Date:
Thu Feb 01 17:53:53 2018 +0000
Revision:
3:28c7d280790e
Parent:
2:cd1fe8c29793 
lab2-part1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
WilliamMarshQMUL 0:a66a8cb0012c 1 #include "mbed.h"
WilliamMarshQMUL 0:a66a8cb0012c 2
WilliamMarshQMUL 0:a66a8cb0012c 3 // Labs 2: Example program for polling an input
WilliamMarshQMUL 0:a66a8cb0012c 4 // --------------------------------------------
WilliamMarshQMUL 0:a66a8cb0012c 5 // The program uses a thread to poll a digital input
WilliamMarshQMUL 0:a66a8cb0012c 6 // - The thread monitors the position of the button
WilliamMarshQMUL 0:a66a8cb0012c 7 // - When the button transitions up and down, a press event is signaled
WilliamMarshQMUL 0:a66a8cb0012c 8 // - Button bounce is guarded against
WilliamMarshQMUL 2:cd1fe8c29793 9 // A second thread (the default one) checks for the press event and toggles the LED
WilliamMarshQMUL 0:a66a8cb0012c 10
Peilingyi 3:28c7d280790e 11 DigitalIn b1(PTD0, PullUp);//change the address
WilliamMarshQMUL 2:cd1fe8c29793 12 DigitalOut led(LED1);
WilliamMarshQMUL 0:a66a8cb0012c 13
WilliamMarshQMUL 0:a66a8cb0012c 14 Thread pollT ; // thread to poll
WilliamMarshQMUL 0:a66a8cb0012c 15 volatile int pressEvent = 0 ; // Variabe set by the polling thread
WilliamMarshQMUL 0:a66a8cb0012c 16
WilliamMarshQMUL 0:a66a8cb0012c 17 enum buttonPos { up, down, bounce }; // Button positions
WilliamMarshQMUL 0:a66a8cb0012c 18 void polling() {
WilliamMarshQMUL 0:a66a8cb0012c 19 buttonPos pos = up ;
WilliamMarshQMUL 0:a66a8cb0012c 20 int bcounter = 0 ;
WilliamMarshQMUL 0:a66a8cb0012c 21 while (true) {
WilliamMarshQMUL 0:a66a8cb0012c 22 switch (pos) {
WilliamMarshQMUL 0:a66a8cb0012c 23 case up :
WilliamMarshQMUL 2:cd1fe8c29793 24 if (!b1.read()) { // now down
WilliamMarshQMUL 0:a66a8cb0012c 25 pressEvent = 1 ; // transition occurred
WilliamMarshQMUL 0:a66a8cb0012c 26 pos = down ;
WilliamMarshQMUL 0:a66a8cb0012c 27 }
WilliamMarshQMUL 0:a66a8cb0012c 28 break ;
WilliamMarshQMUL 0:a66a8cb0012c 29 case down :
WilliamMarshQMUL 2:cd1fe8c29793 30 if (b1 == 1) { // no longer down
WilliamMarshQMUL 0:a66a8cb0012c 31 bcounter = 3 ; // wait four cycles
WilliamMarshQMUL 0:a66a8cb0012c 32 pos = bounce ;
WilliamMarshQMUL 0:a66a8cb0012c 33 }
WilliamMarshQMUL 0:a66a8cb0012c 34 break ;
WilliamMarshQMUL 0:a66a8cb0012c 35 case bounce :
WilliamMarshQMUL 2:cd1fe8c29793 36 if (b1 == 0) { // down again - button has bounced
WilliamMarshQMUL 0:a66a8cb0012c 37 pos = down ; // no event
WilliamMarshQMUL 0:a66a8cb0012c 38 } else if (bcounter == 0) {
WilliamMarshQMUL 0:a66a8cb0012c 39 pos = up ; // delay passed - reset to up
WilliamMarshQMUL 0:a66a8cb0012c 40 } else {
WilliamMarshQMUL 0:a66a8cb0012c 41 bcounter-- ; // continue waiting
WilliamMarshQMUL 0:a66a8cb0012c 42 }
WilliamMarshQMUL 0:a66a8cb0012c 43 break ;
WilliamMarshQMUL 0:a66a8cb0012c 44 }
WilliamMarshQMUL 0:a66a8cb0012c 45 Thread::wait(30);
WilliamMarshQMUL 0:a66a8cb0012c 46 }
WilliamMarshQMUL 0:a66a8cb0012c 47 }
WilliamMarshQMUL 0:a66a8cb0012c 48
WilliamMarshQMUL 2:cd1fe8c29793 49 /* ---- Main function (default thread) ----
WilliamMarshQMUL 2:cd1fe8c29793 50 Note that if this thread completes, nothing else works
WilliamMarshQMUL 2:cd1fe8c29793 51 */
Peilingyi 3:28c7d280790e 52 int main()
Peilingyi 3:28c7d280790e 53 {
Peilingyi 3:28c7d280790e 54 int speed = 1;
Peilingyi 3:28c7d280790e 55 led = 1 ;
WilliamMarshQMUL 2:cd1fe8c29793 56 pollT.start(callback(polling));
WilliamMarshQMUL 2:cd1fe8c29793 57
Peilingyi 3:28c7d280790e 58 while(true)
Peilingyi 3:28c7d280790e 59 {
Peilingyi 3:28c7d280790e 60 if (pressEvent)
Peilingyi 3:28c7d280790e 61 {
Peilingyi 3:28c7d280790e 62 speed++;
Peilingyi 3:28c7d280790e 63
Peilingyi 3:28c7d280790e 64 if (speed >= 5)
Peilingyi 3:28c7d280790e 65 speed = 1;
Peilingyi 3:28c7d280790e 66
Peilingyi 3:28c7d280790e 67 pressEvent = 0;
Peilingyi 3:28c7d280790e 68 }
Peilingyi 3:28c7d280790e 69 led = !led ;
Peilingyi 3:28c7d280790e 70 Thread::wait(200*speed);
WilliamMarshQMUL 0:a66a8cb0012c 71 }
Peilingyi 3:28c7d280790e 72 }