Lab 2 Part 2 - Polling Modified
Fork of digitalInPolling_sample by
main.cpp@3:446895514289, 2018-02-02 (annotated)
- Committer:
- diviavad
- Date:
- Fri Feb 02 17:15:34 2018 +0000
- Revision:
- 3:446895514289
- Parent:
- 2:cd1fe8c29793
Version 1
Who changed what in which revision?
User | Revision | Line number | New 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 | |
WilliamMarshQMUL | 2:cd1fe8c29793 | 11 | DigitalIn b1(PTD0, PullUp); |
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() { |
diviavad | 3:446895514289 | 19 | buttonPos pos = up ;//chose positing in enum |
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 | */ |
WilliamMarshQMUL | 2:cd1fe8c29793 | 52 | int main() { |
diviavad | 3:446895514289 | 53 | // Initially off |
diviavad | 3:446895514289 | 54 | int wait_time= 200; |
diviavad | 3:446895514289 | 55 | pollT.start(callback(polling));//start thread to check button |
diviavad | 3:446895514289 | 56 | int counter=1; |
WilliamMarshQMUL | 0:a66a8cb0012c | 57 | while(true) { |
diviavad | 3:446895514289 | 58 | led = !led; |
WilliamMarshQMUL | 0:a66a8cb0012c | 59 | if (pressEvent) { |
diviavad | 3:446895514289 | 60 | if (counter==2){ |
diviavad | 3:446895514289 | 61 | wait_time=400; |
diviavad | 3:446895514289 | 62 | } |
diviavad | 3:446895514289 | 63 | else if(counter==3){ |
diviavad | 3:446895514289 | 64 | wait_time=600; |
diviavad | 3:446895514289 | 65 | } |
diviavad | 3:446895514289 | 66 | else if(counter==4){ |
diviavad | 3:446895514289 | 67 | wait_time=800; |
diviavad | 3:446895514289 | 68 | } |
diviavad | 3:446895514289 | 69 | else if(counter==5){ |
diviavad | 3:446895514289 | 70 | wait_time=1000; |
diviavad | 3:446895514289 | 71 | counter=0; |
diviavad | 3:446895514289 | 72 | } |
diviavad | 3:446895514289 | 73 | |
WilliamMarshQMUL | 0:a66a8cb0012c | 74 | pressEvent = 0 ; // clear the event variable |
diviavad | 3:446895514289 | 75 | led =!led ;//LED ON |
diviavad | 3:446895514289 | 76 | |
diviavad | 3:446895514289 | 77 | |
diviavad | 3:446895514289 | 78 | counter++; |
WilliamMarshQMUL | 0:a66a8cb0012c | 79 | } |
diviavad | 3:446895514289 | 80 | Thread::wait(wait_time); |
WilliamMarshQMUL | 0:a66a8cb0012c | 81 | } |
WilliamMarshQMUL | 0:a66a8cb0012c | 82 | } |