stephen smitherman / HCSR04

mbed device driver for HC-SR04 ultrasonic range finder

Dependents:   TJPS UltraTest NavigationTest NavigationTest_ ... more

Fork of HCSR04 by Robert Abad

HCSR04.h@2:3ebde19131af, 2013-12-12 (annotated)

Committer:
srsmitherman
Date:
Thu Dec 12 17:22:48 2013 +0000
Revision:
2:3ebde19131af
Parent:
0:5461d44a187c 
Improved missed echo detection.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rabad1 0:5461d44a187c 1 /* File: HCSR04.h
rabad1 0:5461d44a187c 2 * Author: Robert Abad Copyright (c) 2013
rabad1 0:5461d44a187c 3 *
rabad1 0:5461d44a187c 4 * Desc: driver for HCSR04 Ultrasonic Range Finder. The returned range
rabad1 0:5461d44a187c 5 * is in units of meters.
rabad1 0:5461d44a187c 6 *
rabad1 0:5461d44a187c 7 * To use this driver you must call the methods ::startMeas()
rabad1 0:5461d44a187c 8 * and ::getMeas(). The HCSR04 requires a trigger time of
rabad1 0:5461d44a187c 9 * 10 usec (microseconds) which is initiated by ::startMeas().
rabad1 0:5461d44a187c 10 * If a successful measurement is made, getMeas() will return
rabad1 0:5461d44a187c 11 * RANGE_MEAS_VALID. If unsuccessful, initiate a new measurement.
rabad1 0:5461d44a187c 12 *
rabad1 0:5461d44a187c 13 * The datasheet for this device can be found here:
rabad1 0:5461d44a187c 14 * http://www.elecfreaks.com/store/download/product/Sensor/HC-SR04/HC-SR04_Ultrasonic_Module_User_Guide.pdf
rabad1 0:5461d44a187c 15 *
rabad1 0:5461d44a187c 16 * Below is some sample code:
rabad1 0:5461d44a187c 17 *
rabad1 0:5461d44a187c 18 * #include "mbed.h"
rabad1 0:5461d44a187c 19 * #include "HCSR04.h"
rabad1 0:5461d44a187c 20 *
rabad1 0:5461d44a187c 21 * #define PIN_TRIGGER (p14)
rabad1 0:5461d44a187c 22 * #define PIN_ECHO (p15)
rabad1 0:5461d44a187c 23 *
rabad1 0:5461d44a187c 24 * int main(void)
rabad1 0:5461d44a187c 25 * {
rabad1 0:5461d44a187c 26 * HCSR04 rangeFinder( PIN_TRIGGER, PIN_ECHO );
rabad1 0:5461d44a187c 27 * float range;
rabad1 0:5461d44a187c 28 *
rabad1 0:5461d44a187c 29 * while (1)
rabad1 0:5461d44a187c 30 * {
rabad1 0:5461d44a187c 31 * rangeFinder.startMeas();
rabad1 0:5461d44a187c 32 * wait(0.1);
rabad1 0:5461d44a187c 33 * if ( rangeFinder.getMeas(range) == RANGE_MEAS_VALID )
rabad1 0:5461d44a187c 34 * {
rabad1 0:5461d44a187c 35 * printf("range = %f\n\r", range);
rabad1 0:5461d44a187c 36 * }
rabad1 0:5461d44a187c 37 * }
rabad1 0:5461d44a187c 38 * }
rabad1 0:5461d44a187c 39 */
rabad1 0:5461d44a187c 40
rabad1 0:5461d44a187c 41 #ifndef __HCSR04_H__
rabad1 0:5461d44a187c 42 #define __HCSR04_H__
rabad1 0:5461d44a187c 43
rabad1 0:5461d44a187c 44 #include "mbed.h"
rabad1 0:5461d44a187c 45
srsmitherman 2:3ebde19131af 46 #define MTRS_TO_INCH (39.3701)
srsmitherman 2:3ebde19131af 47
rabad1 0:5461d44a187c 48 typedef enum
rabad1 0:5461d44a187c 49 {
rabad1 0:5461d44a187c 50 RANGE_MEAS_INVALID,
rabad1 0:5461d44a187c 51 RANGE_MEAS_VALID
rabad1 0:5461d44a187c 52 } etHCSR04_RANGE_STATUS;
rabad1 0:5461d44a187c 53
srsmitherman 2:3ebde19131af 54
srsmitherman 2:3ebde19131af 55
rabad1 0:5461d44a187c 56 class HCSR04
rabad1 0:5461d44a187c 57 {
rabad1 0:5461d44a187c 58 public:
rabad1 0:5461d44a187c 59 HCSR04( PinName pinTrigger, PinName pinEcho );
rabad1 0:5461d44a187c 60 void startMeas(void);
rabad1 0:5461d44a187c 61 etHCSR04_RANGE_STATUS getMeas(float &rRangeMeters);
srsmitherman 2:3ebde19131af 62
srsmitherman 2:3ebde19131af 63
rabad1 0:5461d44a187c 64 private:
rabad1 0:5461d44a187c 65 DigitalOut trigger;
rabad1 0:5461d44a187c 66 Ticker triggerTicker;
rabad1 0:5461d44a187c 67 InterruptIn echo;
rabad1 0:5461d44a187c 68 Timer echoTimer;
rabad1 0:5461d44a187c 69 unsigned long measTimeStart_us;
rabad1 0:5461d44a187c 70 unsigned long measTimeStop_us;
srsmitherman 2:3ebde19131af 71 unsigned long dTime_us;
srsmitherman 2:3ebde19131af 72 etHCSR04_RANGE_STATUS status;
rabad1 0:5461d44a187c 73
rabad1 0:5461d44a187c 74 void triggerTicker_cb(void); // trigger ticker callback function
rabad1 0:5461d44a187c 75 void ISR_echoRising(void); // ISR for rising edge
rabad1 0:5461d44a187c 76 void ISR_echoFalling(void); // ISR for falling edge
rabad1 0:5461d44a187c 77 };
rabad1 0:5461d44a187c 78
rabad1 0:5461d44a187c 79 #endif /* __HCSR04_H__ */