Diff: ping.cpp

Revision:

0:99ee7c741e9d

Child:

1:72fbcb01291d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ping.cpp	Sun Jul 27 19:12:34 2014 +0000
@@ -0,0 +1,42 @@
+#include "ping.h"
+
+Ping::Ping(PinName signalPin) : mSignalIo(signalPin, PIN_OUTPUT, PullDown, 0), mEvent(signalPin), 
+        mBusy(0), mValid(0), mContinuous(0), mTimer(), mRawReading(0) {
+    mEvent.rise(this, &Ping::start);
+    mEvent.fall(this, &Ping::stop);
+}
+
+bool Ping::startReading() {
+    return this->startReading(false);
+}
+
+bool Ping::startReading(bool continuous) {
+    mContinuous = continuous;
+    if (mBusy) return false;
+    
+    mSignalIo.output();
+    mSignalIo = 0;
+    wait_us(2);
+    mSignalIo = 1;
+    wait_us(10);
+    mSignalIo.input();
+    
+    return true;
+}
+
+void Ping::start() {
+    mBusy = true;
+    mValid = false;
+    mTimer.start();
+    mStartTime = mTimer.read_us();
+}
+
+void Ping::stop() {
+    mBusy = false;
+    mValid = true;
+    // The time it takes is for a round trip.  We divide by two to get the time for one way.
+    mRawReading = (mTimer.read_us() - mStartTime) >> 1;
+    mTimer.stop();
+    mCallback.call(mRawReading);
+    if (mContinuous) this->startReading(mContinuous);
+}
\ No newline at end of file