TVZ Mechatronics Team / HCSR04

A distance measurement class using ultrasonic sensor HC-SR04.

Dependents:   Esercitazione4_4 HC-SR04 Group10_slave Oled_Gus ... more

The purpose of this library is to encourage students to develope their own classes. Instructions how to follow the development of this library for ultrasonic distance measurement are given here.

HCSR04.h@6:cf3e4e307d15, 2016-12-10 (annotated)

Committer:
tbjazic
Date:
Sat Dec 10 08:26:18 2016 +0000
Revision:
6:cf3e4e307d15
Parent:
5:a667b621f625 
Filtering with Ticker object corrected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
tbjazic 0:8871082486ac 1 #ifndef HCSR04_H_TVZMT
tbjazic 0:8871082486ac 2 #define HCSR04_H_TVZMT
tbjazic 0:8871082486ac 3
tbjazic 0:8871082486ac 4 /** A distance measurement class using ultrasonic sensor HC-SR04.
tbjazic 0:8871082486ac 5 *
tbjazic 0:8871082486ac 6 * Example of use:
tbjazic 2:aa59a9c531be 7 * @code
tbjazic 0:8871082486ac 8 * #include "mbed.h"
tbjazic 0:8871082486ac 9 * #include "HCSR04.h"
tbjazic 0:8871082486ac 10 *
tbjazic 5:a667b621f625 11 * Serial pc(USBTX, USBRX);
tbjazic 6:cf3e4e307d15 12 * Timer timer;
tbjazic 5:a667b621f625 13 *
tbjazic 0:8871082486ac 14 * int main() {
tbjazic 5:a667b621f625 15 * HCSR04 sensor(p5, p7);
tbjazic 5:a667b621f625 16 * sensor.setRanges(10, 110);
tbjazic 5:a667b621f625 17 * pc.printf("Min. range = %g cm\n\rMax. range = %g cm\n\r",
tbjazic 5:a667b621f625 18 * sensor.getMinRange(), sensor.getMaxRange());
tbjazic 6:cf3e4e307d15 19 * while(true) {
tbjazic 6:cf3e4e307d15 20 * timer.reset();
tbjazic 6:cf3e4e307d15 21 * timer.start();
tbjazic 6:cf3e4e307d15 22 * sensor.startMeasurement();
tbjazic 6:cf3e4e307d15 23 * while(!sensor.isNewDataReady()) {
tbjazic 6:cf3e4e307d15 24 * // wait for new data
tbjazic 6:cf3e4e307d15 25 * // waiting time depends on the distance
tbjazic 6:cf3e4e307d15 26 * }
tbjazic 5:a667b621f625 27 * pc.printf("Distance: %5.1f mm\r", sensor.getDistance_mm());
tbjazic 6:cf3e4e307d15 28 * timer.stop();
tbjazic 6:cf3e4e307d15 29 * wait_ms(500 - timer.read_ms()); // time the loop
tbjazic 0:8871082486ac 30 * }
tbjazic 0:8871082486ac 31 * }
tbjazic 2:aa59a9c531be 32 * @endcode
tbjazic 0:8871082486ac 33 */
tbjazic 0:8871082486ac 34 class HCSR04 {
tbjazic 0:8871082486ac 35
tbjazic 0:8871082486ac 36 public:
tbjazic 0:8871082486ac 37
tbjazic 0:8871082486ac 38 /** Receives two PinName variables.
tbjazic 0:8871082486ac 39 * @param echoPin mbed pin to which the echo signal is connected to
tbjazic 0:8871082486ac 40 * @param triggerPin mbed pin to which the trigger signal is connected to
tbjazic 0:8871082486ac 41 */
tbjazic 0:8871082486ac 42 HCSR04(PinName echoPin, PinName triggerPin);
tbjazic 0:8871082486ac 43
tbjazic 6:cf3e4e307d15 44 /** Start the measurement. Measurement time depends on the distance.
tbjazic 6:cf3e4e307d15 45 * Maximum measurement time is limited to 25 ms (400 cm).
tbjazic 6:cf3e4e307d15 46 */
tbjazic 6:cf3e4e307d15 47 void startMeasurement();
tbjazic 6:cf3e4e307d15 48
tbjazic 6:cf3e4e307d15 49 /** Returns the distance in cm. Requires previous call of startMeasurement().
tbjazic 0:8871082486ac 50 * @returns distance of the measuring object in cm.
tbjazic 0:8871082486ac 51 */
tbjazic 0:8871082486ac 52 float getDistance_cm();
tbjazic 0:8871082486ac 53
tbjazic 6:cf3e4e307d15 54 /** Returns the distance in mm. Requires previous call of startMeasurement().
tbjazic 4:aae70f15357f 55 * @returns distance of the measuring object in mm.
tbjazic 4:aae70f15357f 56 */
tbjazic 4:aae70f15357f 57 float getDistance_mm();
tbjazic 4:aae70f15357f 58
tbjazic 4:aae70f15357f 59 /** Sets the minimum and maximum ranges between the factory values of 2 cm and 400 cm.
tbjazic 4:aae70f15357f 60 * @param minRange Minimum range in cm. Must be between 2 cm and maxRange.
tbjazic 4:aae70f15357f 61 * @param maxRange Maximum range in cm. Must be between minRange and 400 cm.
tbjazic 4:aae70f15357f 62 */
tbjazic 4:aae70f15357f 63 void setRanges(float minRange, float maxRange);
tbjazic 4:aae70f15357f 64
tbjazic 4:aae70f15357f 65 /** Retreives the minimum sensor range set by the user.
tbjazic 4:aae70f15357f 66 * @returns the minimum sensor range set by the user in cm.
tbjazic 4:aae70f15357f 67 */
tbjazic 4:aae70f15357f 68 float getMinRange();
tbjazic 4:aae70f15357f 69
tbjazic 4:aae70f15357f 70 /** Retreives the maximum sensor range set by the user.
tbjazic 4:aae70f15357f 71 * @returns the maximum sensor range set by the user in cm.
tbjazic 4:aae70f15357f 72 */
tbjazic 4:aae70f15357f 73 float getMaxRange();
tbjazic 4:aae70f15357f 74
tbjazic 6:cf3e4e307d15 75 /** Checks if the new data is ready.
tbjazic 6:cf3e4e307d15 76 * @returns true if new data is ready, false otherwise.
tbjazic 6:cf3e4e307d15 77 */
tbjazic 6:cf3e4e307d15 78 bool isNewDataReady();
tbjazic 6:cf3e4e307d15 79
tbjazic 0:8871082486ac 80 private:
tbjazic 0:8871082486ac 81
tbjazic 0:8871082486ac 82 InterruptIn echo; // echo pin
tbjazic 0:8871082486ac 83 DigitalOut trigger; // trigger pin
tbjazic 0:8871082486ac 84 Timer timer; // echo pulsewidth measurement
tbjazic 0:8871082486ac 85 float distance; // store the distance in cm
tbjazic 3:9a7899cf5e3a 86 float minDistance; // minimum measurable distance
tbjazic 3:9a7899cf5e3a 87 float maxDistance; // maximum measurable distance
tbjazic 6:cf3e4e307d15 88 Timeout triggerTimeout, echoTimeout;
tbjazic 6:cf3e4e307d15 89 bool newDataReady, timerStarted;
tbjazic 0:8871082486ac 90
tbjazic 0:8871082486ac 91 /** Start the timer. */
tbjazic 0:8871082486ac 92 void startTimer();
tbjazic 0:8871082486ac 93
tbjazic 0:8871082486ac 94 /** Stop the timer. */
tbjazic 0:8871082486ac 95 void stopTimer();
tbjazic 0:8871082486ac 96
tbjazic 0:8871082486ac 97 /** Initialization. */
tbjazic 0:8871082486ac 98 void init();
tbjazic 0:8871082486ac 99
tbjazic 6:cf3e4e307d15 100 void turnOffTrigger();
tbjazic 0:8871082486ac 101 };
tbjazic 0:8871082486ac 102
tbjazic 0:8871082486ac 103 #endif