Diff: HCSR04.h

Revision:

6:cf3e4e307d15

Parent:

5:a667b621f625

--- a/HCSR04.h	Mon Dec 07 09:57:48 2015 +0000
+++ b/HCSR04.h	Sat Dec 10 08:26:18 2016 +0000
@@ -9,15 +9,24 @@
  * #include "HCSR04.h"
  *
  * Serial pc(USBTX, USBRX);
+ * Timer timer;
  *
  * int main() {
  *     HCSR04 sensor(p5, p7);
  *     sensor.setRanges(10, 110);
  *     pc.printf("Min. range = %g cm\n\rMax. range = %g cm\n\r",
  *       sensor.getMinRange(), sensor.getMaxRange());
- *     while(1) {
+ *     while(true) {
+ *         timer.reset();
+ *         timer.start();
+ *         sensor.startMeasurement();
+ *         while(!sensor.isNewDataReady()) {
+ *             // wait for new data
+ *             // waiting time depends on the distance
+ *         }
  *         pc.printf("Distance: %5.1f mm\r", sensor.getDistance_mm());
- *         wait_ms(500);
+ *         timer.stop();
+ *         wait_ms(500 - timer.read_ms()); // time the loop
  *     }
  * }
  * @endcode
@@ -32,12 +41,17 @@
      */
     HCSR04(PinName echoPin, PinName triggerPin);
     
-    /** Calculates the distance in cm, with the calculation time of approximatelly 23.7 ms.
+    /** Start the measurement. Measurement time depends on the distance.
+     *  Maximum measurement time is limited to 25 ms (400 cm).
+     */
+    void startMeasurement();
+    
+    /** Returns the distance in cm. Requires previous call of startMeasurement().
      * @returns distance of the measuring object in cm.
      */
     float getDistance_cm();
     
-    /** Calculates the distance in mm, with the calculation time of approximatelly 23.7 ms.
+    /** Returns the distance in mm. Requires previous call of startMeasurement().
      * @returns distance of the measuring object in mm.
      */
     float getDistance_mm();
@@ -58,6 +72,11 @@
      */
     float getMaxRange();
     
+    /** Checks if the new data is ready.
+     * @returns true if new data is ready, false otherwise.
+     */
+    bool isNewDataReady();
+    
     private:
     
     InterruptIn echo;       // echo pin
@@ -66,6 +85,8 @@
     float distance;         // store the distance in cm
     float minDistance;      // minimum measurable distance
     float maxDistance;      // maximum measurable distance
+    Timeout triggerTimeout, echoTimeout;
+    bool newDataReady, timerStarted;
     
     /** Start the timer. */
     void startTimer();
@@ -76,8 +97,7 @@
     /** Initialization. */
     void init();
     
-    /** Start the measurement. */
-    void startMeasurement();
+    void turnOffTrigger();
 };
 
 #endif
\ No newline at end of file