Diff: HC-SR04/HCSR04.h

Revision:

0:5f61200516d7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HC-SR04/HCSR04.h	Thu May 11 16:57:18 2017 +0000
@@ -0,0 +1,103 @@
+#ifndef HCSR04_H_TVZMT
+#define HCSR04_H_TVZMT
+
+/** A distance measurement class using ultrasonic sensor HC-SR04.
+ *  
+ * Example of use:
+ * @code
+ * #include "mbed.h"
+ * #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(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());
+ *         timer.stop();
+ *         wait_ms(500 - timer.read_ms()); // time the loop
+ *     }
+ * }
+ * @endcode
+ */
+class HCSR04 {
+    
+    public:
+    
+    /** Receives two PinName variables.
+     * @param echoPin mbed pin to which the echo signal is connected to
+     * @param triggerPin mbed pin to which the trigger signal is connected to
+     */
+    HCSR04(PinName echoPin, PinName triggerPin);
+    
+    /** 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();
+    
+    /** Returns the distance in mm. Requires previous call of startMeasurement().
+     * @returns distance of the measuring object in mm.
+     */
+    float getDistance_mm();
+    
+    /** Sets the minimum and maximum ranges between the factory values of 2 cm and 400 cm.
+     *  @param minRange Minimum range in cm. Must be between 2 cm and maxRange.
+     *  @param maxRange Maximum range in cm. Must be between minRange and 400 cm.
+     */
+    void setRanges(float minRange, float maxRange);
+    
+    /** Retreives the minimum sensor range set by the user.
+     * @returns the minimum sensor range set by the user in cm.
+     */
+    float getMinRange();
+    
+    /** Retreives the maximum sensor range set by the user.
+     * @returns the maximum sensor range set by the user in cm.
+     */
+    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
+    DigitalOut trigger;     // trigger pin
+    Timer timer;            // echo pulsewidth measurement
+    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();
+    
+    /** Stop the timer. */
+    void stopTimer();
+    
+    /** Initialization. */
+    void init();
+    
+    void turnOffTrigger();
+};
+
+#endif
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