main.cpp

00001 #include "mbed.h"
00002 
00003 // There is a LOT of code repetition here.
00004 // Following bad practise, you can almost copy and paste the code for the red LED to add the greedn
00005 // Further task: Consider ways to reduce this to make it simpler to maintain.
00006 
00007 void sw1TimeOutHandler();
00008 void sw1RisingEdge();
00009 void sw1FallingEdge();
00010 void sw2TimeOutHandler();
00011 void sw2RisingEdge();
00012 void sw2FallingEdge();
00013 
00014 #define EDGE_RISEN 1
00015 #define EDGE_FALLEN 0
00016 
00017 //Global Objects
00018 DigitalOut  red_led(D7);
00019 DigitalOut  green_led(D5);
00020 InterruptIn   sw1(D4);
00021 InterruptIn   sw2(D3);
00022 
00023 Timeout sw1TimeOut;             //Used to prevent switch bounce
00024 Timeout sw2TimeOut;
00025 int sw1State = EDGE_FALLEN;     //Initial state for switch 1
00026 int sw2State = EDGE_FALLEN;
00027 
00028 //Interrupt service routine for handling the timeout
00029 void sw1TimeOutHandler() {
00030     sw1TimeOut.detach();            //Stop the timeout counter firing
00031 
00032     //Which event does this follow?
00033     switch (sw1State) {
00034     case EDGE_RISEN:    
00035         sw1.fall(&sw1FallingEdge);  //Now wait for a falling edge
00036         break;
00037     case EDGE_FALLEN:
00038         sw1.rise(&sw1RisingEdge);   //Now wait for a rising edge
00039         break;
00040     } //end switch 
00041 }
00042 
00043 //Interrupt service routine for a rising edge (press)
00044 void sw1RisingEdge() {
00045     sw1.rise(NULL);             //Disable detecting more rising edges
00046     sw1State = EDGE_RISEN;      //Flag state
00047     sw1TimeOut.attach(&sw1TimeOutHandler, 0.2);    //Start timeout timer
00048 }
00049 
00050 //Interrupt service routive for SW1 falling edge (release)
00051 void sw1FallingEdge() {
00052     sw1.fall(NULL);                         //Disable this interrupt
00053     red_led = !red_led;                     //Toggle LED    
00054     sw1State = EDGE_FALLEN;                 //Flag state
00055     sw1TimeOut.attach(&sw1TimeOutHandler, 0.2);    //Start timeout counter    
00056 }
00057 
00058 void sw2TimeOutHandler() {
00059     sw2TimeOut.detach();            //Stop the timeout counter firing
00060 
00061     //Which event does this follow?
00062     switch (sw2State) {
00063     case EDGE_RISEN:    
00064         sw2.fall(&sw2FallingEdge);  //Now wait for a falling edge
00065         break;
00066     case EDGE_FALLEN:
00067         sw2.rise(&sw2RisingEdge);   //Now wait for a rising edge
00068         break;
00069     } //end switch 
00070 }
00071 
00072 //Interrupt service routine for a rising edge (press)
00073 void sw2RisingEdge() {
00074     sw2.rise(NULL);             //Disable detecting more rising edges
00075     sw2State = EDGE_RISEN;      //Flag state
00076     sw2TimeOut.attach(&sw2TimeOutHandler, 0.2);    //Start timeout timer
00077 }
00078 
00079 //Interrupt service routive for SW1 falling edge (release)
00080 void sw2FallingEdge() {
00081     sw2.fall(NULL);                         //Disable this interrupt
00082     green_led = !green_led;                //Toggle LED    
00083     sw2State = EDGE_FALLEN;                 //Flag state
00084     sw2TimeOut.attach(&sw2TimeOutHandler, 0.2);    //Start timeout counter    
00085 }
00086 
00087 //Main - only has to initialise and sleep
00088 int main() {
00089     //Initial logging message
00090     puts("START");
00091     
00092     //Initial state
00093     red_led     = 0; //Set RED LED to OFF
00094     green_led   = 0;
00095     
00096     //Configure interrupts, wait for first rising edge
00097     sw1.rise(&sw1RisingEdge);
00098     sw2.rise(&sw2RisingEdge);
00099     
00100     //Main Polling Loop
00101     while (true) {
00102         
00103         //Put CPU back to sleep
00104         sleep();
00105         
00106         //You can ONLY reach this point if an ISR wakes the CPU
00107         puts("ISR just woke the MPU");
00108         
00109     } //end while
00110 
00111 }