Akhil Nair / Mbed OS Lab21

lab 2 interrupts

main.cpp@3:05b6a1431a6b, 2018-01-16 (annotated)

Committer:
WilliamMarshQMUL
Date:
Tue Jan 16 18:14:21 2018 +0000
Revision:
3:05b6a1431a6b
Parent:
2:071f22412cdc
Child:
4:728667196916
Convert to mbed 5

Who changed what in which revision?

UserRevisionLine numberNew contents of line
WilliamMarshQMUL 0:a66a8cb0012c 1 #include "mbed.h"
WilliamMarshQMUL 0:a66a8cb0012c 2
WilliamMarshQMUL 1:13e0c1956b54 3 // Labs 2: Example program for using an interrupt (or callback)
WilliamMarshQMUL 1:13e0c1956b54 4 // -----------------------------------------------------------
WilliamMarshQMUL 1:13e0c1956b54 5 // A callback function (corresponding to an ISR) is called when a button
WilliamMarshQMUL 1:13e0c1956b54 6 // is pressed
WilliamMarshQMUL 1:13e0c1956b54 7 // The callback uses a shared variable to signal another thread
WilliamMarshQMUL 0:a66a8cb0012c 8
WilliamMarshQMUL 1:13e0c1956b54 9 InterruptIn button(PTD0);
WilliamMarshQMUL 3:05b6a1431a6b 10 DigitalOut led(LED_GREEN);
WilliamMarshQMUL 0:a66a8cb0012c 11
WilliamMarshQMUL 1:13e0c1956b54 12 volatile int pressEvent = 0 ;
WilliamMarshQMUL 0:a66a8cb0012c 13
WilliamMarshQMUL 3:05b6a1431a6b 14 // This function is invoked when then interrupt occurs
WilliamMarshQMUL 3:05b6a1431a6b 15 // Signal that the button has been pressed
WilliamMarshQMUL 1:13e0c1956b54 16 // Note: bounce may occur
WilliamMarshQMUL 1:13e0c1956b54 17 void buttonCallback(){
WilliamMarshQMUL 1:13e0c1956b54 18 pressEvent = 1 ;
WilliamMarshQMUL 0:a66a8cb0012c 19 }
WilliamMarshQMUL 0:a66a8cb0012c 20
WilliamMarshQMUL 3:05b6a1431a6b 21 /* ---- Main function (default thread) ----
WilliamMarshQMUL 3:05b6a1431a6b 22 Note that if this thread completes, nothing else works
WilliamMarshQMUL 3:05b6a1431a6b 23 */
WilliamMarshQMUL 3:05b6a1431a6b 24 int main() {
WilliamMarshQMUL 3:05b6a1431a6b 25 button.mode(PullUp); // Ensure button i/p has pull up
WilliamMarshQMUL 3:05b6a1431a6b 26 button.fall(&buttonCallback) ; // Attach function to falling edge
WilliamMarshQMUL 3:05b6a1431a6b 27
WilliamMarshQMUL 0:a66a8cb0012c 28 while(true) {
WilliamMarshQMUL 3:05b6a1431a6b 29 // Toggle the LED every time the button is pressed
WilliamMarshQMUL 0:a66a8cb0012c 30 if (pressEvent) {
WilliamMarshQMUL 0:a66a8cb0012c 31 led = !led ;
WilliamMarshQMUL 1:13e0c1956b54 32 pressEvent = 0 ; // Clear the event variable
WilliamMarshQMUL 0:a66a8cb0012c 33 }
WilliamMarshQMUL 0:a66a8cb0012c 34 Thread::wait(100) ;
WilliamMarshQMUL 0:a66a8cb0012c 35 }
WilliamMarshQMUL 0:a66a8cb0012c 36 }