NMEAGPS Class Reference

API for the NMEA GPS Module. More...

Detailed Description

• ID: nmea_gps
• Name: Generic Serial Interface for GPS NMEA Devices
• Category: gps
• Manufacturer: dfrobot seeed
• Connection: uart gpio
• Other Names: VK2828u7 ublox LEA-6H

This driver was tested with a number of GPS devices that emit NMEA data via a serial interface of some sort (typically a UART).

The I2C capablity was tested with a UBLOX LEA-6H based GPS shield from DFRobot. Currently, the I2C capability is only supported for UBLOX devices (or compatibles) that conform to the specifications outlined in the u-blox6 Receiver Description Protocol Specification, Chapter 4, DDC Port.

An example using the UART.

    // Instantiate a NMEA_GPS sensor on uart 0 at 9600 baud with enable
    // pin on D3.  If you do not need an enable pin, you can specify -1.
    upm::NMEAGPS sensor(0, 9600, 3);

    // loop, dumping NMEA data out as fast as it comes in
    while (shouldRun && sensor.dataAvailable(5000)) {
        cout << sensor.readStr(bufferLength);
    }

    if (shouldRun)
        cerr << "Timed out" << endl;

An example using I2C.

    // Instantiate a NMEA_GPS UBLOX based i2c sensor on i2c bus 0 at
    // address 0x42
    upm::NMEAGPS sensor(0, 0x42);

    // loop, dumping NMEA data out as fast as it comes in
    while (shouldRun) {
        if (sensor.dataAvailable(0))
            upm_delay_us(100);
        else
            cout << sensor.readStr(bufferLength);
    }

Public Member Functions
	NMEAGPS (unsigned int uart, unsigned int baudrate, int enable_pin)
	NMEAGPS (unsigned int bus, uint8_t addr)
	~NMEAGPS ()
std::string	readStr (size_t size)
int	writeStr (std::string buffer)
void	enable (bool enable)
void	setBaudrate (unsigned int baudrate)
bool	dataAvailable (unsigned int millis)

Protected Attributes
nmea_gps_context	m_nmea_gps

Constructor & Destructor Documentation

NMEAGPS	(	unsigned int	uart,
		unsigned int	baudrate,
		int	enable_pin
	)

NMEAGPS object constructor for a UART

Parameters

uart	Specify which uart to use.
baudrate	Specify the baudrate to use. The device defaults to 9600 baud.
enable_pin	Specify the GPIO pin to use for the enable pin, -1 to not use an enable pin.

NMEAGPS	(	unsigned int	bus,
		uint8_t	addr
	)

NMEAGPS object constructor for a UBLOX I2C interface

Parameters

bus	Specify which the I2C bus to use.
addr	Specify the I2C address to use. For UBLOX devices, this typically defaults to 0x42.

~NMEAGPS

(

)

NMEAGPS object destructor

Member Function Documentation

std::string readStr

(

size_t

size

)

Read character data from the device.

Parameters

size	The maximum number of characters to read.

Returns

string containing the data read.

int writeStr

(

std::string

buffer

)

Write character data to the device. This is only valid for a UART device.

Parameters

buffer

The string containing the data to write.

Returns

The number of bytes written.

void enable

(

bool

enable

)

Enable or disable the device. When disabled, the device enters a low power mode and does not emit NMEA data. It will still maintain location data however.

Parameters

enable

true to enable the device, false otherwise.

void setBaudrate

(

unsigned int

baudrate

)

Set the baudrate of the device. By default, the constructor will set the baudrate to 9600. This is only valid for UART devices.

Parameters

baudrate

The baud rate to set for the device.

bool dataAvailable

(

unsigned int

millis

)

Determine whether there is data available to be read. In the case of a UART, this function will wait up to "millis" milliseconds for data to become available. In the case of an I2C device, the millis argument is ignored and the function will return immediately, indicating whether data is available.

Parameters

millis

The number of milliseconds to wait for data to become available.

Returns

true if data is available to be read, false otherwise.

Collaboration diagram for NMEAGPS:

---

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

• src/nmea_gps/nmea_gps.hpp
• src/nmea_gps/nmea_gps.cxx