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Lab 2 Part 2 - Polling Modified
Fork of digitalInPolling_sample by
main.cpp
- Committer:
- diviavad
- Date:
- 2018-02-02
- Revision:
- 3:446895514289
- Parent:
- 2:cd1fe8c29793
File content as of revision 3:446895514289:
#include "mbed.h" // Labs 2: Example program for polling an input // -------------------------------------------- // The program uses a thread to poll a digital input // - The thread monitors the position of the button // - When the button transitions up and down, a press event is signaled // - Button bounce is guarded against // A second thread (the default one) checks for the press event and toggles the LED DigitalIn b1(PTD0, PullUp); DigitalOut led(LED1); Thread pollT ; // thread to poll volatile int pressEvent = 0 ; // Variabe set by the polling thread enum buttonPos { up, down, bounce }; // Button positions void polling() { buttonPos pos = up ;//chose positing in enum int bcounter = 0 ; while (true) { switch (pos) { case up : if (!b1.read()) { // now down pressEvent = 1 ; // transition occurred pos = down ; } break ; case down : if (b1 == 1) { // no longer down bcounter = 3 ; // wait four cycles pos = bounce ; } break ; case bounce : if (b1 == 0) { // down again - button has bounced pos = down ; // no event } else if (bcounter == 0) { pos = up ; // delay passed - reset to up } else { bcounter-- ; // continue waiting } break ; } Thread::wait(30); } } /* ---- Main function (default thread) ---- Note that if this thread completes, nothing else works */ int main() { // Initially off int wait_time= 200; pollT.start(callback(polling));//start thread to check button int counter=1; while(true) { led = !led; if (pressEvent) { if (counter==2){ wait_time=400; } else if(counter==3){ wait_time=600; } else if(counter==4){ wait_time=800; } else if(counter==5){ wait_time=1000; counter=0; } pressEvent = 0 ; // clear the event variable led =!led ;//LED ON counter++; } Thread::wait(wait_time); } }