sonar.h

00001 #include "mbed.h"
00002 
00003 #ifndef SONAR_H
00004 #define SONAR_H
00005 /*** @file Driver for Maxbotix sonar modules
00006  * Uses pulse width input to read range results.
00007  * @author Daniel Casner <http://www.danielcasner.org>
00008  *
00009  * Known Issues:
00010  * If a timer rollover occures during a sample, the driver will drop that sample.
00011  */
00012  
00013  /** Object representation of a sonar instance
00014   */
00015  class Sonar {
00016  public:
00017     /** Sets up the driver and starts taking measurements
00018      * @param input The pin to read pulses from
00019      * @param t A running timer instance used to measure pulse width.
00020      * Note that the timer must have been started or results will be
00021      * invalid.
00022      */
00023     Sonar(PinName input, Timer& t);
00024     
00025     /// Returns range in cm as int
00026     int read();
00027     
00028     /// Returns the range in CM as an int
00029     operator int();
00030     
00031  private:
00032     /// Inturrupt at start of pulse
00033     void pulseStart();
00034     /// Interrupt at end of pulse
00035     void pulseStop();
00036     
00037     /// Interrupt driver for the input pin
00038     InterruptIn interrupt;
00039     /// Reference to global timer instance
00040     Timer& time;
00041     /// Time of the start of the current pulse
00042     int pulseStartTime;
00043     /// The most recent sample
00044     int range;
00045  };
00046  
00047  #endif