Diff: SWPoll.hpp

Revision:

0:f9a18207d99c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SWPoll.hpp	Fri Nov 23 14:42:48 2018 +0000
@@ -0,0 +1,70 @@
+#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
+    int status;    // ""
+    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, int flag) : sw(gpioIn), status(flag) {
+        state = LOW;
+        t.reset();
+        flag = 0;
+    }    
+    //Destructor - should the instance go out of scope, this is called
+    ~SWPoll() {
+        //Shut down
+        t.stop();
+        t.reset();
+        flag = 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) {
+                flag = !flag; //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  
+    }
+};
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