Diff: hcsr04.h

Revision:

15:b10859606504

Parent:

14:a30aa3b29a2e

Child:

31:4ef53fbd6759

--- a/hcsr04.h	Fri Mar 07 21:49:22 2014 +0000
+++ b/hcsr04.h	Tue Mar 11 19:58:31 2014 +0000
@@ -3,12 +3,11 @@
 //  ECE 510 Embedded Systems, Roy Kravitz
 //
 // HCSR04 ultrasonic sensor class using interrupts and allowing multiple instances.
-// You can use the same trigger pin for multiple instances, the echo is received and 
-// measurement calculated based on the echo input alone (when the echo signal goes high
-// the timer is started, when the echo signal goes low the timer value in microseconds
-// is saved as the length, and the timer is stopped and reset.  Length calculation is done
-// when the length is requested (either inches or centimeters) using the appropriate
-// function. 
+// You can use the same trigger pin for multiple instances; the echo is received and 
+// measurement calculated based on the echo input alone. (when the echo signal goes high,
+// the timer is started. When the echo signal goes low, the timer value in microseconds
+// is saved as the length, and the timer is stopped and reset) Length calculation is done
+// when the length is requested (either inches or centimeters). 
 
 #ifndef MBED_HCSR04_H
 #define MBED_HCSR04_H
@@ -23,8 +22,8 @@
 class hcsr04 {
 
 private:
-    InterruptIn *_echo_int;                        // pin to receive echo signal
-    DigitalOut trigger_out;                    // pin to send the trigger signal
+    InterruptIn *_echo_int;                        // pin to receive echo signal; input
+    DigitalOut trigger_out;                    // pin to send the trigger signal; output
     Timer timer;                            // timer to track length of pulse
     float value;                            // to store the last pulse length        
 
@@ -32,9 +31,9 @@
     bool measuring;                         // true while the echo signal is high (measurement in progress)
     hcsr04(PinName trigger, PinName echo) : trigger_out(trigger) { // _pass the names to the pin configuration                                                   
         //trigger_out = new DigitalOut( trigger );
-        _echo_int = new InterruptIn( echo );
-        _echo_int->rise(this, &hcsr04::timer_start);
-        _echo_int->fall(this, &hcsr04::calc_measurement);
+        _echo_int = new InterruptIn( echo );                // interrupts
+        _echo_int->rise(this, &hcsr04::timer_start);        // when trigger is sent
+        _echo_int->fall(this, &hcsr04::calc_measurement);   // when echo is received
         measuring = false;
     }
 
@@ -65,8 +64,9 @@
         return value / CM_DIVISOR;
     }
         
-    /* void pulse(void) {  // Rohan's code
-        trigger();
+    /* void hscr04_main(void) {  // Rohan's code
+        //trigger();
+        // delay
         while(measuring == false);
         // interrupts call timer_start() and calc_measurement()
     }