Akhil Nair / Mbed OS Lab21

lab 2 interrupts

main.cpp@2:071f22412cdc, 2017-01-24 (annotated)

Committer:
WilliamMarshQMUL
Date:
Tue Jan 24 18:31:35 2017 +0000
Revision:
2:071f22412cdc
Parent:
1:13e0c1956b54
Child:
3:05b6a1431a6b
Change to falling edge

Who changed what in which revision?

UserRevisionLine numberNew contents of line
WilliamMarshQMUL 0:a66a8cb0012c 1 #include "mbed.h"
WilliamMarshQMUL 0:a66a8cb0012c 2 #include "rtos.h"
WilliamMarshQMUL 0:a66a8cb0012c 3
WilliamMarshQMUL 1:13e0c1956b54 4 // Labs 2: Example program for using an interrupt (or callback)
WilliamMarshQMUL 1:13e0c1956b54 5 // -----------------------------------------------------------
WilliamMarshQMUL 1:13e0c1956b54 6 // A callback function (corresponding to an ISR) is called when a button
WilliamMarshQMUL 1:13e0c1956b54 7 // is pressed
WilliamMarshQMUL 1:13e0c1956b54 8 // The callback uses a shared variable to signal another thread
WilliamMarshQMUL 0:a66a8cb0012c 9
WilliamMarshQMUL 1:13e0c1956b54 10 InterruptIn button(PTD0);
WilliamMarshQMUL 0:a66a8cb0012c 11 DigitalOut led(LED_RED);
WilliamMarshQMUL 0:a66a8cb0012c 12
WilliamMarshQMUL 1:13e0c1956b54 13 Thread flashT ;
WilliamMarshQMUL 1:13e0c1956b54 14 volatile int pressEvent = 0 ;
WilliamMarshQMUL 0:a66a8cb0012c 15
WilliamMarshQMUL 1:13e0c1956b54 16 // Signal when the button is pressed
WilliamMarshQMUL 1:13e0c1956b54 17 // Note: bounce may occur
WilliamMarshQMUL 1:13e0c1956b54 18 void buttonCallback(){
WilliamMarshQMUL 1:13e0c1956b54 19 pressEvent = 1 ;
WilliamMarshQMUL 0:a66a8cb0012c 20 }
WilliamMarshQMUL 0:a66a8cb0012c 21
WilliamMarshQMUL 0:a66a8cb0012c 22 // Toggle the LED every time the button is pressed
WilliamMarshQMUL 1:13e0c1956b54 23 // Note: the LED could be toggled in the callback
WilliamMarshQMUL 0:a66a8cb0012c 24 void flash() {
WilliamMarshQMUL 0:a66a8cb0012c 25 while(true) {
WilliamMarshQMUL 0:a66a8cb0012c 26 if (pressEvent) {
WilliamMarshQMUL 0:a66a8cb0012c 27 led = !led ;
WilliamMarshQMUL 1:13e0c1956b54 28 pressEvent = 0 ; // Clear the event variable
WilliamMarshQMUL 0:a66a8cb0012c 29 }
WilliamMarshQMUL 0:a66a8cb0012c 30 Thread::wait(100) ;
WilliamMarshQMUL 0:a66a8cb0012c 31 }
WilliamMarshQMUL 0:a66a8cb0012c 32 }
WilliamMarshQMUL 0:a66a8cb0012c 33
WilliamMarshQMUL 0:a66a8cb0012c 34 int main() {
WilliamMarshQMUL 1:13e0c1956b54 35 button.mode(PullUp); // Ensure button i/p has pull up
WilliamMarshQMUL 2:071f22412cdc 36 button.fall(&buttonCallback) ; // Attach function to falling edge
WilliamMarshQMUL 1:13e0c1956b54 37
WilliamMarshQMUL 1:13e0c1956b54 38 flashT.start(&flash) ; // Start the flashing thread running
WilliamMarshQMUL 0:a66a8cb0012c 39 }