Diff: main.cpp

Revision:

0:3590cc227050

Child:

1:b7cc6bbb077d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Jul 13 14:48:11 2017 +0000
@@ -0,0 +1,128 @@
+#include "mbed.h"
+
+void updateState(int &sw, int &swState, DigitalOut &led, Timer &tmr) ;
+
+DigitalOut  red_led(D7);
+DigitalOut  green_led(D5);
+DigitalIn   SW1(D4);
+DigitalIn   SW2(D3);
+//This is the solution based on the proposed flowchart.
+//The precise delay required may need adjusting
+
+Timer tmr1;
+Timer tmr2;
+
+#define WAITING4PRESS 0
+#define WAITING4BOUNCE_RISING 1
+#define WAITING4RELEASE 2
+#define WAITING4BOUNCE_FALLING 4
+
+int main() {
+    //Initial logging message
+    puts("START");
+    
+    //Initial state
+    red_led    = 0; //Set RED LED to OFF
+    green_led  = 0;
+    
+    //Switch state
+    int sw1State = 0;
+    int sw2State = 0;
+    
+    //Timers
+    tmr1.stop();
+    tmr1.reset();
+    tmr2.stop();
+    tmr2.reset();
+
+    //Initial logging message
+    puts("Entering state WAITING4PRESS");
+
+    //Main Polling Loop
+    while (true) {
+        
+        //Poll inputs (without blocking)
+        int sw1 = SW1;
+        int sw2 = SW2;
+        
+        updateState(sw1, sw1State, red_led,   tmr1);
+        updateState(sw2, sw2State, green_led, tmr2);
+                
+    } //end while
+
+}
+
+// Update the state for a given switch and LED pair
+// Parameters:
+// sw is the switch input, 0 for released and 1 for pressed, passed by value
+// swState is an integer that keeps a record of state, passed by reference (updated by the function)
+// led is of type DigitalOut, connected to a LED
+// tmr is of type Timer, a reference to  unique instance of a timer
+// This function cannot be called by an ISR
+void updateState(int sw, int &swState, DigitalOut &led, Timer &tmr) 
+{
+        //LED
+        switch (swState) {
+            
+        //Waiting for switch to be pressed
+        case WAITING4PRESS:
+
+            if (sw == 1) {
+                //Output: start timer
+                tmr.reset();
+                tmr.start();
+                
+                //Next state
+                swState =  WAITING4BOUNCE_RISING;  
+                puts("Entering state: WAITING4BOUNCE_RISING");
+            } 
+            break;
+            
+        //Waiting for 50ms to elapse
+        case WAITING4BOUNCE_RISING:      
+            if (tmr.read_ms() > 50) {
+                //Outputs: Stop timer
+                tmr.stop();
+                //Next state
+                swState =  WAITING4RELEASE;  
+                puts("Entering state: WAITING4RELEASE");                
+            }    
+            break;
+        
+        //Waiting for switch to be released
+        case WAITING4RELEASE:
+            if (sw == 0) {
+                //Outputs: Toggle the LED and start timer
+                led = !led;
+                tmr.reset();
+                tmr.start();                
+                //Next state
+                swState =  WAITING4BOUNCE_FALLING;  
+                puts("Entering state: WAITING4BOUNCE_FALLING");  
+            } 
+            break;
+            
+        //Waiting 50ms for switch bounce         
+        case WAITING4BOUNCE_FALLING:
+            if (tmr.read_ms() > 50) {
+                //Outputs: Reset timer 1
+                tmr.stop();
+                tmr.reset();
+                
+                //Next state:
+                swState = WAITING4PRESS;
+                puts("Entering state: WAITING4PRESS"); 
+            }
+            break;
+            
+        default:
+            //Something has gone very wrong
+            tmr.stop();
+            tmr.reset();
+            led = 0;
+            swState = WAITING4PRESS;
+            puts("ERROR");
+            break;
+        
+        } //end switch
+    } //end function
\ No newline at end of file