Diff: SRF05.cpp

Revision:

0:e758665e072c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SRF05.cpp	Fri Nov 19 22:34:56 2010 +0000
@@ -0,0 +1,61 @@
+/* mbed SRF05 Ultrasonic Rangefiner Library
+ * Copyright (c) 2007-2010, cstyles, sford
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "SRF05.h"
+#include "mbed.h"
+
+SRF05::SRF05(PinName trigger, PinName echo) 
+    : _trigger(trigger), _echo(echo) {    
+        
+    // Attach interrupts
+    _echo.rise(this, &SRF05::_rising);
+    _echo.fall(this, &SRF05::_falling);
+    _ticker.attach(this, &SRF05::_startRange, 0.1);     
+}
+  
+void SRF05::_startRange() {
+    // send a trigger pulse, 20uS long
+    _trigger = 1;
+    wait (0.000002);
+    _trigger = 0;
+}
+
+// Clear and start the timer at the begining of the echo pulse
+void SRF05::_rising(void) {
+    _timer.reset();
+    _timer.start();
+}
+
+// Stop and read the timer at the end of the pulse
+void SRF05::_falling(void) {
+    _timer.stop();
+    _dist = _timer.read_us()/58.0;
+}
+
+float SRF05::read(void) {
+    // spin until there is a good value
+    return (_dist);
+}
+
+SRF05::operator float() {
+    return read();
+}