Revision 2:253054128736, committed 2014-09-28

Comitter:

jatinsha

Date:

Sun Sep 28 03:02:57 2014 +0000

Parent:

1:03c191369089

Child:

3:d18d3609c800

Commit message:

timer with Start, Pause/Unpause and Reset ; 24ms error (slow) in 3.9 seconds

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TextLCD.lib	Sun Sep 28 03:02:57 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/simon/code/TextLCD/#308d188a2d3a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/keypad.lib	Sun Sep 28 03:02:57 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/DimiterK/code/keypad/#1fa357ea3fcc

--- a/main.cpp	Sun Jan 01 20:57:57 2012 +0000
+++ b/main.cpp	Sun Sep 28 03:02:57 2014 +0000
@@ -1,12 +1,151 @@
-#include "mbed.h"
+/*
+CIS 541 - Embedded Systems for Life Critical Applications
+Assignment3
+Timer using mBed 1768
+
+Developers - Jatin Sharma and Samarth Shah
+
+References
+1. Timer                    : http://mbed.org/handbook/Timer
+2. String format modifiers  : http://www.cdf.toronto.edu/~ajr/209/notes/printf.html
+3. Keyboard Input           : http://mbed.org/handbook/SerialPC
+4. Interrupt attach         : http://mbed.org/handbook/Serial
+5. Enum tutorial            : http://stackoverflow.com/questions/1102542/how-to-define-an-enumerated-type-enum-in-c
+6. 
+
+*/
+
 
-DigitalOut myled(LED1);
+#include "mbed.h"
+#include "TextLCD.h"
+
+// RS, E, D4 - D7 for 4 bit mode
+#define RS p15
+#define E p16
+#define D4 p17
+#define D5 p18
+#define D6 p19
+#define D7 p20
+#define interval 10
+
+TextLCD lcd(RS, E, D4, D5, D6, D7, TextLCD::LCD16x2);
+Timer timerDisplay, timerReference;
+Serial pc(USBTX, USBRX); // tx, rx
+
+int miliSeconds, centiSeconds, seconds, minutes;
+int currentReferenceTime, previousReferenceTime;
+int calculatedTimeInterval, referenceTimeInterval, runningError;
+char keyboardInput;
 
-int main() {
-    while(1) {
-        myled = 1;
-        wait(0.2);
-        myled = 0;
-        wait(0.2);
+typedef enum {Running, Paused, Reset} state_t;
+state_t timerState = Reset;
+ 
+void callback() 
+{
+    // Keyboard input : you need to actually read from the serial to clear the RX interrupt
+    if(keyboardInput = pc.getc())
+    {
+        if((keyboardInput == 's' || keyboardInput == 'S')) 
+        {
+            if(timerState == Reset)
+            {
+                timerReference.start();
+                timerDisplay.start();
+                timerState = Running;
+            }
+        }
+        if((keyboardInput == 'p' || keyboardInput == 'P')) 
+        {
+            if(timerState == Running)
+            {
+                timerReference.stop();
+                timerDisplay.stop();
+                timerState = Paused;
+            }
+            else if(timerState == Paused)
+            {
+                timerReference.start();
+                timerDisplay.start();
+                timerState = Running;
+            }
+        } 
+        if((keyboardInput == 'r' || keyboardInput == 'R')) 
+        {  
+            if(timerState == Paused)
+            {
+                // Reset timer
+                timerReference.reset();
+                timerDisplay.reset();
+                timerState = Reset;
+                
+                // Reset variables
+                miliSeconds = seconds = minutes = 0;
+                currentReferenceTime = previousReferenceTime = 0;
+                calculatedTimeInterval = referenceTimeInterval = runningError = 0;
+                lcd.locate(0,0);
+                lcd.printf("00:00:00");
+                lcd.locate(0,1);
+                lcd.printf("000000");
+            }
+        } 
     }
+} 
+ 
+int main() 
+{
+    // interrupt service routine
+    pc.attach(&callback);
+    
+    // local variable
+    miliSeconds = seconds = minutes = 0;
+    currentReferenceTime = previousReferenceTime = 0;
+    calculatedTimeInterval = referenceTimeInterval = runningError = 0;
+    //timerReference.start();
+    //timerDisplay.start();
+    
+    // Initial display work
+    lcd.locate(0,0);
+    lcd.printf("00:00:00");
+    
+    while(1)
+    {
+        if( timerDisplay.read_ms() >= interval)
+        {
+            timerDisplay.reset();
+            
+            // Calculate display variables
+            miliSeconds += interval;
+    
+            centiSeconds += (miliSeconds / 10);
+            miliSeconds %= 10;
+    
+            seconds += (centiSeconds / 100);
+            centiSeconds %= 100;
+    
+            minutes += (seconds / 60);
+            seconds %= 60;
+            
+            // Error correction using referenceClock
+            currentReferenceTime = timerReference.read_us();
+            referenceTimeInterval = currentReferenceTime - previousReferenceTime;
+            runningError += (referenceTimeInterval - interval*1000);
+
+            //miliSeconds += runningError;
+            previousReferenceTime = currentReferenceTime;
+                
+            
+            // Display time on LCD
+            lcd.locate(0,0);
+            lcd.printf("%02d:%02d:%02d",minutes, seconds, centiSeconds);
+            
+            lcd.locate(0,1);
+            lcd.printf("%06d", runningError);
+            }
+            
+            
+            
+        
+
+    }
+    
 }