Revision 0:f14a3481cfc3, committed 2016-10-24

Comitter:

Mattinico

Date:

Mon Oct 24 12:53:49 2016 +0000

Commit message:

ghj

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HCSR04.cpp	Mon Oct 24 12:53:49 2016 +0000
@@ -0,0 +1,67 @@
+#include "mbed.h"
+#include "HCSR04.h"
+ 
+HCSR04::HCSR04(PinName echoPin, PinName triggerPin) : echo(echoPin), trigger(triggerPin) {
+    init();
+}
+ 
+void HCSR04::init() {
+    /** configure the rising edge to start the timer */
+    echo.rise(this, &HCSR04::startTimer);
+    
+    /** configure the falling edge to stop the timer */
+    echo.fall(this, &HCSR04::stopTimer);
+    
+    distance = -1;      // initial distance
+    minDistance = 2;
+    maxDistance = 400;
+}
+ 
+void HCSR04::startTimer() {
+    timer.start(); // start the timer
+}
+ 
+void HCSR04::stopTimer() {
+    timer.stop(); // stop the timer
+}
+ 
+void HCSR04::startMeasurement() {
+    trigger = 1;
+    wait_us(10);
+    trigger = 0;
+    wait_us(23660); // just enough time to measure 400 cm
+    timer.stop(); // just in case echo fall did not occur
+    distance = timer.read() * 1e6 / 58;
+    if (distance < minDistance)
+        distance = minDistance;
+    if (distance > maxDistance)
+        distance = maxDistance;
+    timer.reset();
+}
+ 
+float HCSR04::getDistance_cm() {
+    startMeasurement();
+    return distance;
+}
+ 
+float HCSR04::getDistance_mm() {
+    startMeasurement();
+    return distance * 10;
+}
+ 
+void HCSR04::setRanges(float minRange, float maxRange) {
+    if (minRange < maxRange) {
+        if (minRange >= 2) 
+            minDistance = minRange;
+        if (maxRange <= 400)
+            maxDistance = maxRange;
+    }
+}
+ 
+float HCSR04::getMinRange() {
+    return minDistance;
+}
+ 
+float HCSR04::getMaxRange() {
+    return maxDistance;
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HCSR04.h	Mon Oct 24 12:53:49 2016 +0000
@@ -0,0 +1,83 @@
+#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);
+ *
+ * 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) {
+ *         pc.printf("Distance: %5.1f mm\r", sensor.getDistance_mm());
+ *         wait_ms(500);
+ *     }
+ * }
+ * @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);
+    
+    /** Calculates the distance in cm, with the calculation time of approximatelly 23.7 ms.
+     * @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 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();
+    
+    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
+    
+    /** Start the timer. */
+    void startTimer();
+    
+    /** Stop the timer. */
+    void stopTimer();
+    
+    /** Initialization. */
+    void init();
+    
+    /** Start the measurement. */
+    void startMeasurement();
+};
+ 
+#endif
\ No newline at end of file