Diff: HCSR04.h

Revision:

0:5461d44a187c

Child:

2:3ebde19131af

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HCSR04.h	Sun Nov 24 21:45:46 2013 +0000
@@ -0,0 +1,72 @@
+/* File: HCSR04.h
+ * Author: Robert Abad  Copyright (c) 2013
+ *
+ * Desc: driver for HCSR04 Ultrasonic Range Finder.  The returned range
+ *       is in units of meters.
+ *
+ *       To use this driver you must call the methods ::startMeas()
+ *       and ::getMeas().  The HCSR04 requires a trigger time of
+ *       10 usec (microseconds) which is initiated by ::startMeas().
+ *       If a successful measurement is made, getMeas() will return
+ *       RANGE_MEAS_VALID.  If unsuccessful, initiate a new measurement.
+ *
+ *       The datasheet for this device can be found here:
+ *       http://www.elecfreaks.com/store/download/product/Sensor/HC-SR04/HC-SR04_Ultrasonic_Module_User_Guide.pdf
+ *
+ *       Below is some sample code:
+ *
+ *       #include "mbed.h"
+ *       #include "HCSR04.h"
+ *
+ *       #define PIN_TRIGGER    (p14)
+ *       #define PIN_ECHO       (p15)
+ *
+ *       int main(void)
+ *       {
+ *           HCSR04 rangeFinder( PIN_TRIGGER, PIN_ECHO );
+ *           float range;
+ *           
+ *           while (1)
+ *           {
+ *               rangeFinder.startMeas();
+ *               wait(0.1);
+ *               if ( rangeFinder.getMeas(range) == RANGE_MEAS_VALID )
+ *               {
+ *                   printf("range = %f\n\r", range);
+ *               }
+ *           }
+ *       }
+ */
+
+#ifndef __HCSR04_H__
+#define __HCSR04_H__
+
+#include "mbed.h"
+
+typedef enum
+{
+    RANGE_MEAS_INVALID,
+    RANGE_MEAS_VALID
+} etHCSR04_RANGE_STATUS;
+
+class HCSR04
+{
+public:
+    HCSR04( PinName pinTrigger, PinName pinEcho );
+    void startMeas(void);
+    etHCSR04_RANGE_STATUS getMeas(float &rRangeMeters);
+
+private:
+    DigitalOut trigger;
+    Ticker triggerTicker;
+    InterruptIn echo;
+    Timer echoTimer;
+    unsigned long measTimeStart_us;
+    unsigned long measTimeStop_us;
+    
+    void triggerTicker_cb(void);    // trigger ticker callback function
+    void ISR_echoRising(void);      // ISR for rising edge
+    void ISR_echoFalling(void);     // ISR for falling edge
+};
+
+#endif /* __HCSR04_H__ */