URM37 Class Reference

API for the DFRobot URM37 Ultrasonic Ranger. More...

Detailed Description

• ID: urm37
• Name: DFRobot URM37 Ultrasonic Ranger
• Category: sound
• Manufacturer: dfrobot
• Connection: uart ainput gpio
• Link: http://www.dfrobot.com/index.php?route=product/product&product_id=53

The driver was tested with the DFRobot URM37 Ultrasonic Ranger, V4. It has a range of between 5 and 500 centimeters (cm). It supports both analog distance measurement, and UART based temperature and distance measurements. This driver does not support PWM measurement mode.

For UART operation, the only supported baud rate is 9600. In addition, you must ensure that the UART TX/RX pins are configured for TTL operation (the factory default) rather than RS232 operation, or permanent damage to your URM37 and/or MCU will result. On power up, the LED indicator will blink one long pulse, followed by one short pulse to indicate TTL operation. See the DFRobot wiki for more information:

(https://www.dfrobot.com/wiki/index.php?title=URM37_V4.0_Ultrasonic_Sensor_%28SKU:SEN0001%29)

An example using analog mode

  // Instantiate a URM37 sensor on analog pin A0, reset pin on D2,
  // trigger pin on D3 with an analog reference voltage of 5.0
  upm::URM37 *sensor = new upm::URM37(0, 2, 3, 5.0);

  // Every half a second, sample the URM37 and output the measured
  // distance in cm.

  while (shouldRun)
    {
      cout << "Detected distance (cm): " << sensor->getDistance() << endl;
      usleep(500000);
    }

An example using UART mode

  // Instantiate a URM37 sensor on UART 0, with the reset pin on D2
  upm::URM37 *sensor = new upm::URM37(0, 2);
  
  // Every half a second, sample the URM37 and output the measured
  // distance in cm, and temperature in degrees C

  while (shouldRun)
    {
      cout << "Detected distance (cm): " << sensor->getDistance() << endl;
      cout << "Temperature (C): " << sensor->getTemperature() << endl;
      
      usleep(500000);
    }

Public Member Functions
	URM37 (int aPin, int resetPin, int triggerPin, float aref=5.0)
	URM37 (int uart, int resetPin)
	~URM37 ()
void	reset ()
float	getDistance (int degrees=0)
float	getTemperature ()
uint8_t	readEEPROM (uint8_t addr)
void	writeEEPROM (uint8_t addr, uint8_t value)

Protected Member Functions
void	init ()
std::string	sendCommand (std::string cmd)

Protected Attributes
mraa::Uart *	m_uart
mraa::Aio *	m_aio
mraa::Gpio *	m_gpioTrigger
mraa::Gpio	m_gpioReset

Constructor & Destructor Documentation

URM37	(	int	aPin,
		int	resetPin,
		int	triggerPin,
		float	aref = 5.0
	)

URM37 object constructor (Analog mode)

Parameters

aPin	Analog pin to use
resetPin	GPIO pin to use for reset
triggerPin	GPIO pin to use for triggering a distance measurement
aref	The analog reference voltage, default 5.0

URM37	(	int	uart,
		int	resetPin
	)

URM37 object constructor (UART mode)

Parameters

uart	Default UART to use (0 or 1).
resetPin	GPIO pin to use for reset

~URM37

(

)

URM37 object destructor

Member Function Documentation

void reset

(

)

Reset the device. This will take approximately 3 seconds to complete.

float getDistance

(

int

degrees = 0

)

Get the distance measurement. A return value of 65535.0 in UART mode indicates an invalid measurement.

Parameters

degrees

in UART mode, this specifies the degrees to turn an attached PWM servo connected to the MOTO output on the URM37. Default is 0. Valid values are 0-270. This option is ignored in analog mode.

Returns

The measured distance in cm

float getTemperature

(

void

)

Get the temperature measurement. This is only valid in UART mode.

Returns

The measured temperature in degrees C

uint8_t readEEPROM

(

uint8_t

addr

)

In UART mode only, read a value from the EEPROM and return it.

Parameters

addr	The address in the EEPROM to read. Valid values are between 0x00-0x04.

Returns

The EEPROM value at addr

void writeEEPROM	(	uint8_t	addr,
		uint8_t	value
	)

In UART mode only, write a value into an address on the EEPROM.

Parameters

addr	The address in the EEPROM to write. Valid values are between 0x00-0x04.
value	The value to write

Returns

The EEPROM value at addr

---

The documentation for this class was generated from the following files:

• /iotdk/jenkins/workspace/upm-doc-stable/src/urm37/urm37.h
• /iotdk/jenkins/workspace/upm-doc-stable/src/urm37/urm37.cxx