Diff: HCSR04.cpp

Revision:

0:f14a3481cfc3

--- /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;
+}
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