sonar.h

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