Arduino library for communicating with uBlox GPS receivers.
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README.md

UBLOX

Arduino library for communicating with uBlox GPS receivers.

Description

uBlox produces standard and high precision GPS receivers with options for RTK, PPP, and multi-constellation GNSS. These receivers feature high sensitivity, minimal acquisition times, and small form factors.

This library communicates with the uBlox receivers using the UBX protocol and the UBX-NAV-PVT packet, which is available on uBlox 7 and 8 series receivers. Hardware serial is used for receiving the data packets.

Usage

Installation

Simply clone or download and extract the zipped library into your Arduino/libraries folder.

Setup your uBlox receiver to output the UBX-NAV-PVT packet. Additional setup options include the desired GPS update frequency, the serial baud rate, and the expected dynamical environment. Setup of uBlox receivers can be accomplished using the uBlox u-center software.

Object Declaration

UBLOX(HardwareSerial& bus,uint32_t baud) A UBLOX object should be declared, specifying the hardware serial port the uBlox GPS receiver is connected to and the baud rate. The specified baud rate should match the baud rate setup in the GPS receiver configuration. For example, the following code declares a UBLOX object called gps located on the hardware serial port 1 with a baud rate of 115200:

UBLOX gps(Serial1,115200);

Setup Functions

void begin() This should be called in your setup function. It initializes the serial communication between the microcontroller and uBlox GPS receiver. For example, the following code begins serial communication:

gps.begin();

Data Collection Functions

bool readSensor() readSensor() reads data from the uBlox receiver and parses the UBX-NAV-PVT packet. When a complete packet is received with a valid checksum, readSensor() returns true. For example, placing the following code in the loop function will print the latitude, in degrees, to the screen at the GPS update frequency.

if(gps.readSensor()) {
	Serial.println(gps.getLatitude_deg(),10);
}

Data Retrieval

The most recent valid packet is stored in the UBLOX object. Data fields can be retrieved using the following functions, which support both Imperial and SI units.

Imperial SI Description
uint32_t getTow_ms() GPS time of week of the navigation solution, ms
uint16_t getYear() UTC year
uint8_t getMonth() UTC month
uint8_t getDay() UTC day
uint8_t getHour() UTC hour
uint8_t getMin() UTC minute
uint8_t getSec() UTC second
int32_t getNanoSec() UTC fraction of a second, ns*
uint8_t getNumSatellites() Number of satellites used in the navigation solution
double getLongitude_deg() double getLongitude_rad() Longitude
double getLatitude_deg() double getLatitude_rad() Latitude
double getEllipsoidHeight_ft() double getEllipsoidHeight_m() Height above the ellipsoid
double getMSLHeight_ft() double getMSLHeight_m() Height above mean sea level
double getHorizontalAccuracy_ft() double getHorizontalAccuracy_m() Horizontal accuracy estimate
double getVerticalAccuracy_ft() double getVerticalAccuracy_m() Vertical accuracy estimate
double getNorthVelocity_fps() double getNorthVelocity_ms() NED north velocity
double getEastVelocity_fps() double getEastVelocity_ms() NED east velocity
double getDownVelocity_fps() double getDownVelocity_ms() NED down velocity
double getGroundSpeed_fps() double getGroundSpeed_ms() 2D ground speed
double getSpeedAccuracy_fps() double getSpeedAccuracy_ms() Speed accuracy estimate
double getMotionHeading_deg() double getMotionHeading_rad() 2D heading of motion
double getVehicleHeading_deg() double getVehicleHeading_rad() 2D vehicle heading
double getHeadingAccuracy_deg() double getHeadingAccuracy_rad() Heading accuracy estimate
float getMagneticDeclination_deg() float getMagneticDeclination_rad() Magnetic declination
float getMagneticDeclinationAccuracy_deg() float getMagneticDeclinationAccuracy_rad() Magnetic declination accuracy estimate
float getpDOP() Position dilution of precision
enum FixType getFixType() Fix type, see below
enum PowerSaveMode getPowerSaveMode() Power save mode, see below
enum CarrierPhaseStatus getCarrierPhaseStatus() Carrier phase status, see below
bool isGnssFixOk() Valid fix, within DOP and accuracy masks
bool isDiffCorrApplied() Differential corrections were applied
bool isHeadingValid() Heading of vehicle is valid
bool isConfirmedDate() UTC date validity could be confirmed
bool isConfirmedTime() UTC time validity could be confirmed
bool isTimeDateConfirmationAvail() Info about UTC date and time validity confirmation is available
bool isValidDate() Valid UTC date
bool isValidTime() Valid UTC time
bool isTimeFullyResolved() UTC time of day has been fully resolved, no seconds uncertainty
bool isMagneticDeclinationValid() Valid magnetic declination estimate

* The various agencies try to keep the GNSS and UTC references synchronized at the tick event of the second. Short term perturbations in clocks may result in GPS second event being ahead of or behind the UTC second event by up to a microsecond. Hence, fraction of a second may be positive or negative.

The following enum describes the fix type:

enum UBLOX::FixType Description
NO_FIX No Fix
DEAD_RECKONING Dead reckoning only
FIX_2D 2D-fix
FIX_3D 3D-fix
GNSS_AND_DEAD_RECKONING GNSS + dead reckoning combined
TIME_ONLY time only fix

The following enum describes the power save modes:

enum UBLOX::PowerSaveMode Description
NOT_ACTIVE PSM is not active
ENABLED Enabled (an intermediate state before Acquisition state)
ACQUISITION Acquisition
TRACKING Tracking
OPTIMIZED_TRACKING Power optimized tracking
INACTIVE Inactive

The following enum describes the carrier phase status:

enum UBLOX::CarrierPhaseStatus Description
NO_SOL No carrier phase range solution
FLOAT_SOL Float solution (no fixed integer carrier phase measurements used to calculate the solution)
FIXED_SOL Fixed solution (one or more fixed integer carrier phase range measurements used to calculate the solution)

Wiring

Please refer to your microcontroller documentation for hardware serial port pin information. For development purposes, the uBlox NEO 7P receiver available from CSG Shop and the uBlox M8 receiver available from HobbyKing were used.

For the uBlox M8 receiver available from HobbyKing, taking the red wire as pin 1, the following is the GPS receiver pinout:

Pin Description
1 Not Connected
2 Not Connected
3 5V
4 RX (connect to TX)
5 TX (connect to RX)
6 GND