Revision 4:f30ca79f4676, committed 2017-10-24

Comitter:

noutram

Date:

Tue Oct 24 06:59:20 2017 +0000

Parent:

3:a39db8aa11e8

Child:

5:ac0eea152e50

Commit message:

Basic starter code for Task330

Changed in this revision

--- a/SWPoll.hpp	Mon Oct 23 12:28:09 2017 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,71 +0,0 @@
-#include "mbed.h"
-
-class SWPoll {
-private:
-    enum State {LOW, LOW_DEBOUNCE, HIGH, HIGH_DEBOUNCE};
-    State state;        // Internal state
-    DigitalIn& sw;      // These are references (aliases) and MUST be initialised
-    DigitalOut& led;    // ""
-    Timer t;            // Each instance has it's own timer, so this is is finite
-    
-public:
-    //Constructor - MUST be given two parameters (for the switch and led) BY REFERENCE
-    SWPoll(DigitalIn& gpioIn, DigitalOut& gpioOut) : sw(gpioIn), led(gpioOut) {
-        state = LOW;
-        t.reset();
-        led = 0;
-    }    
-    //Destructor - should the instance go out of scope, this is called
-    ~SWPoll() {
-        //Shut down
-        t.stop();
-        t.reset();
-        led = 0;   
-    }
-    //The public API - poll the switches
-    //Bascially, a mealy machine - uses a timer to manage switch bounce
-    void poll() {
-        switch (state) 
-        {
-        //Waiting for switch to rise:
-        case LOW:
-            if (sw == 1) {
-                state = LOW_DEBOUNCE;
-                t.reset();
-                t.start();
-            }
-            break;
-            
-        case LOW_DEBOUNCE:
-            if (t.read_ms() >= 200) {
-                state = HIGH;
-                t.stop();
-                t.reset();    
-            }
-            break;
-        
-        case HIGH:
-            if (sw == 0) {
-                led = !led; //Toggle output on state transition  
-                state = HIGH_DEBOUNCE;
-                t.reset(); //(purely defensive)
-                t.start();
-            }
-            break;
-        case HIGH_DEBOUNCE:
-            if (t.read_ms() >= 200) {
-                state = LOW;
-                t.stop();
-                t.reset();  
-            }
-            break;            
-         default:
-            t.stop();
-            t.reset();    
-            state = LOW;
-            break;
-        }  //end switch
-        
-        //This is a Mealy Machine - so no output logic follows  
-    }
-};
\ No newline at end of file

--- a/main.cpp	Mon Oct 23 12:28:09 2017 +0000
+++ b/main.cpp	Tue Oct 24 06:59:20 2017 +0000
@@ -16,6 +16,9 @@
 
 //The code below is hugely flawed and is only to
 //illustrate the problem of blocking hardware
+
+// TASK - add some code to address the problem of switch bounce
+
 int main() {
     
     //Light up
@@ -28,19 +31,12 @@
     while(1) { 
     
         while (sw1 == RELEASED) {};
-        wait(0.2);
         while (sw1 == PRESSED) {};    
         red_led = !red_led;
-        wait(0.2);
 
         while (sw2 == RELEASED) {};
-        wait(0.2);
         while (sw2 == PRESSED) {};    
         green_led = !green_led;
-        wait(0.2);
-
-        yellow_led = !yellow_led;
-        wait(0.5);
 
         //Flash the yellow
         yellow_led = !yellow_led;