Class for reading or writing a u-blox command. More...

#include <UbloxGPS.h>

Inheritance diagram for UbloxCommandBase:

Public Member Functions
	UbloxCommandBase (uint8_t *buffer, size_t bufferSize)
	Construct a UbloxCommandBase object. Normally you'd use UbloxCommand instead, which handles the buffer management for you. More...

virtual	~UbloxCommandBase ()
	Destructor.

bool	decode (char ch)
	Decode a single character. More...

void	discardToNextSync1 ()
	Used internally to discard invalid data. You probably won't need to call this.

void	updateChecksum ()
	When preparing a command to send, updates the checksum, sync, and length bytes. More...

void	calculateChecksum (uint8_t &ckA, uint8_t &ckB) const
	Calculates the checksum based on the data in the buffer. More...

void	addHandler (UbloxMessageHandler *handler)
	Add a message handler. More...

void	removeHandler (UbloxMessageHandler *handler)
	Remove a message handler. More...

void	callHandlers ()
	Used internally to call all of the message handlers that match this class and id.

uint8_t	getMsgClass () const
	Gets the message class of the current command. More...

uint8_t	getMsgId () const
	Gets the message ID of the current command. More...

void	setClassId (uint8_t msgClass, uint8_t msgId)
	When sending a message, sets the message class and ID. More...

size_t	getPayloadLen () const
	Gets the payload length, the number of bytes available from getData()

const uint8_t *	getData () const
	Get a const pointer to the data payload. More...

bool	getData (size_t offset, void *data, size_t dataLen) const
	Copies data from the buffer. More...

bool	setData (size_t offset, const void *data, size_t dataLen)
	Set data in the buffer. More...

bool	appendData (const void *data, size_t dataLen)
	Appends data into the buffer at the current payloadLen. More...

bool	fillData (uint8_t value, size_t dataLen)
	Works like appendData(), but fill with a value instead. More...

uint8_t	getU1 (size_t offset) const
	Get a uint8_t value at offset. More...

bool	setU1 (size_t offset, uint8_t value)
	Set a uint8_t value at offset in the payload. More...

bool	appendU1 (uint8_t value)
	Append a uint8_t value to the current end of the payload. More...

int8_t	getI1 (size_t offset) const
	Get a int8_t value (signed) at offset. More...

bool	setI1 (size_t offset, int8_t value)
	Set a int8_t value at offset in the payload. More...

bool	appendI1 (int8_t value)
	Append a int8_t value to the current end of the payload. More...

uint16_t	getU2 (size_t offset) const
	Get a uint16_t value (little endian) at offset. More...

bool	setU2 (size_t offset, uint16_t value)
	Set a uint16_t value at offset in the payload. More...

bool	appendU2 (uint16_t value)
	Append a uint16_t value to the current end of the payload. More...

int16_t	getI2 (size_t offset) const
	Get a int16_t value (little endian, signed) at offset. More...

bool	setI2 (size_t offset, int16_t value)
	Set an int16_t value at offset in the payload. More...

bool	appendI2 (int16_t value)
	Append an int16_t value to the current end of the payload. More...

uint32_t	getU4 (size_t offset) const
	Get a uint32_t value (little endian, 4 bytes) at offset. More...

bool	setU4 (size_t offset, uint32_t value)
	Set a uint32_t value at offset in the payload. More...

bool	appendU4 (uint32_t value)
	Append a uint32_t value to the current end of the payload. More...

int32_t	getI4 (size_t offset) const
	Get a int32_t value (little endian, 4 bytes, signed) at offset. More...

bool	setI4 (size_t offset, int32_t value)
	Set an int16_t value at offset in the payload. More...

bool	appendI4 (int32_t value)
	Append a int32_t value to the current end of the payload. More...

float	getR4 (size_t offset) const
	Get a float value (4 bytes) at offset. More...

bool	setR4 (size_t offset, float value)
	Set an float (4 byte floating point) value at offset in the payload. More...

bool	appendR4 (float value)
	Append a float (4 byte floating point) value to the current end of the payload. More...

double	getR8 (size_t offset) const
	Get a double value (8 bytes) at offset. More...

bool	setR8 (size_t offset, double value)
	Set an double (8 byte floating point) value at offset in the payload. More...

bool	appendR8 (double value)
	Append a double (8 byte floating point) value to the current end of the payload. More...

const uint8_t *	getBuffer () const
	Get a pointer to the buffer, typically to send data. More...

size_t	getSendLength () const
	Get the length of the data, typically to send it. More...

Protected Types
enum	State { State::LOOKING_FOR_START, State::LOOKING_FOR_LENGTH, State::LOOKING_FOR_MESSAGE }
	u-blox parsing state constants More...

Protected Attributes
uint8_t *	buffer
	Buffer to hold data (received data or data for composing a packet to send)

size_t	bufferSize
	Size of the buffer. Maximum payload is bufferSize - HEADER_PLUS_CRC_LEN.

size_t	bufferOffset = 0
	Current offset being written to in buffer when using encode()

size_t	payloadLen = 0
	Length of the data payload (0 = no data). This does not include the header or CRC.

State	state = State::LOOKING_FOR_START
	Current parsing state.

std::vector< UbloxMessageHandler * >	handlers
	Vector of message handler objects, contains filter and callback function to handle incoming messages.

Static Protected Attributes
static const uint8_t	SYNC_1 = 0xb5
	value of the first sync byte at buffer[0]

static const uint8_t	SYNC_2 = 0x62
	value of the second sync byte at buffer[1]

static const size_t	CLASS_OFFSET = 2
	offset in buffer where the message class is stored

static const size_t	ID_OFFSET = 3
	offset in buffer where the message ID is stored

static const size_t	DATA_OFFSET = 6
	offset in buffer where data begins (after sync, class, id, and length)

static const size_t	HEADER_PLUS_CRC_LEN = 8
	size of the header data (6 bytes) plus CRC (2 bytes). Minimum size of a valid packet with 0 bytes of payload data.

static const size_t	CRC_START_OFFSET = 2
	offset in buffer where the CRC calculation starts (does not include sync bytes)

static const size_t	CRC_HEADER_LEN = 4
	number of header bytes included in the CRC. The total CRC length is this plus payloadLen.

Detailed Description

Class for reading or writing a u-blox command.

You normally won't use this class directly, but will do so indirectly two ways:

Using UbloxCommand<> a templated version with a buffer to store a commmand you're building and will evenutally send to the modem
Using Ublox, the class for managing the modem, which subclasses this for received messages and acknowledgements.

Member Enumeration Documentation

◆ State

enum UbloxCommandBase::State

strongprotected

u-blox parsing state constants

Enumerator
LOOKING_FOR_START	Looking for the first sync byte (SYNC_1, 0xb5)
LOOKING_FOR_LENGTH	Waiting for DATA_OFFSET bytes to arrive so we can check the length.
LOOKING_FOR_MESSAGE	Waiting for the rest of the message (HEADER_PLUS_CRC_LEN + payloadLen bytes)

Constructor & Destructor Documentation

◆ UbloxCommandBase()

UbloxCommandBase::UbloxCommandBase	(	uint8_t *	buffer,
		size_t	bufferSize
	)

Construct a UbloxCommandBase object. Normally you'd use UbloxCommand instead, which handles the buffer management for you.

Parameters

buffer	Pointer a buffer. Must remain valid for the life of this object. Must not be NULL.
bufferSize	Size of the buffer, a minimum of HEADER_PLUS_CRC_LEN (8) bytes. You will overwrite memory if the buffer is smaller than that.

Member Function Documentation

◆ addHandler()

void UbloxCommandBase::addHandler ( UbloxMessageHandler * handler )

Add a message handler.

Parameters

handler A pointer to a filled in UbloxMessageHandler structure.

Note the handler object must remain valid until removeHandler is called on it, so you probably want to make it a global variable or allocated with new. The exception is if you have a blocking function call and add and remove the handler within the scope of the function, then you can allocate the object on the stack.

◆ appendData()

bool UbloxCommandBase::appendData	(	const void *	data,
		size_t	dataLen
	)

Appends data into the buffer at the current payloadLen.

Parameters

data	Pointer to the data to copy from.
dataLen	The length of the data in bytes.

Returns: true if it was copied or false if not

The data will be copied only if it will fit in the buffer entirely. The data will never be truncated. The payloadLen will be increased by dataLen bytes.

◆ appendI1()

bool UbloxCommandBase::appendI1 ( int8_t value )

inline

Append a int8_t value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit.

◆ appendI2()

bool UbloxCommandBase::appendI2 ( int16_t value )

inline

Append an int16_t value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied.

◆ appendI4()

bool UbloxCommandBase::appendI4 ( int32_t value )

inline

Append a int32_t value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied.

◆ appendR4()

bool UbloxCommandBase::appendR4 ( float value )

inline

Append a float (4 byte floating point) value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied.

◆ appendR8()

bool UbloxCommandBase::appendR8 ( double value )

inline

Append a double (8 byte floating point) value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied.

◆ appendU1()

bool UbloxCommandBase::appendU1 ( uint8_t value )

inline

Append a uint8_t value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit.

◆ appendU2()

bool UbloxCommandBase::appendU2 ( uint16_t value )

inline

Append a uint16_t value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied.

◆ appendU4()

bool UbloxCommandBase::appendU4 ( uint32_t value )

inline

Append a uint32_t value to the current end of the payload.

Parameters

value The value to append

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied.

◆ calculateChecksum()

void UbloxCommandBase::calculateChecksum	(	uint8_t &	ckA,
		uint8_t &	ckB
	)		const

Calculates the checksum based on the data in the buffer.

The checksum is calculated not including the sync bytes or the CRC itself. This method returns the checksum values as parameters, so you can compare them.

The updateChecksum() method is typically used to calculate it for sending.

◆ decode()

bool UbloxCommandBase::decode ( char ch )

Decode a single character.

This is called after reading data from the GPS by serial or I2C.

◆ fillData()

bool UbloxCommandBase::fillData	(	uint8_t	value,
		size_t	dataLen
	)

Works like appendData(), but fill with a value instead.

Parameters

value	The uint8_t value to set. Often 0 to initialize to zero.
dataLen	The number of bytes to fill with value.

Handy for pre-creating zero-filled command buffers that are zeroed out.

◆ getBuffer()

const uint8_t* UbloxCommandBase::getBuffer ( ) const

inline

Get a pointer to the buffer, typically to send data.

This is a pointer to the first sync byte.

◆ getData() [1/2]

const uint8_t* UbloxCommandBase::getData ( ) const

inline

Get a const pointer to the data payload.

There are other methods to copy the data, and read out values like U2, R4, etc..

◆ getData() [2/2]

bool UbloxCommandBase::getData	(	size_t	offset,
		void *	data,
		size_t	dataLen
	)		const

Copies data from the buffer.

Parameters

offset	The offset to being reading from. This is relative to the data payload, so 0 is the first byte of payload data (not the sync byte)
data	Buffer to copy data into
dataLen	The length of the data. This must be <= (payloadLen - offset)

Returns: true if the data could be retrieved or false if it could not

Will only return true if all of the data can be returned. If offset + dataLen > the payloadLen the false will be returned and no data will be returned.

◆ getI1()

int8_t UbloxCommandBase::getI1 ( size_t offset ) const

inline

Get a int8_t value (signed) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getI2()

int16_t UbloxCommandBase::getI2 ( size_t offset ) const

inline

Get a int16_t value (little endian, signed) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getI4()

int32_t UbloxCommandBase::getI4 ( size_t offset ) const

inline

Get a int32_t value (little endian, 4 bytes, signed) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getMsgClass()

uint8_t UbloxCommandBase::getMsgClass ( ) const

inline

Gets the message class of the current command.

This can be used from a message handler to find the message class of the message that is being handled.

◆ getMsgId()

uint8_t UbloxCommandBase::getMsgId ( ) const

inline

Gets the message ID of the current command.

This can be used from a message handler to find the message id of the message that is being handled.

◆ getR4()

float UbloxCommandBase::getR4 ( size_t offset ) const

Get a float value (4 bytes) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getR8()

double UbloxCommandBase::getR8 ( size_t offset ) const

Get a double value (8 bytes) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getSendLength()

size_t UbloxCommandBase::getSendLength ( ) const

inline

Get the length of the data, typically to send it.

It's the length from the first sync byte through the last CRC byte, including the data payload.

◆ getU1()

uint8_t UbloxCommandBase::getU1 ( size_t offset ) const

Get a uint8_t value at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getU2()

uint16_t UbloxCommandBase::getU2 ( size_t offset ) const

Get a uint16_t value (little endian) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ getU4()

uint32_t UbloxCommandBase::getU4 ( size_t offset ) const

Get a uint32_t value (little endian, 4 bytes) at offset.

Parameters

offset The offset relative to the payload, so 0 is the first byte of the payload

◆ removeHandler()

void UbloxCommandBase::removeHandler ( UbloxMessageHandler * handler )

Remove a message handler.

Parameters

handler The handler to remove (same value you passed to addHandler)

Note this will not free handler as it can't know if it was allocated on the stack, as a class member, global variable, or new. If you allocated the object with new, don't forget to delete it!

◆ setClassId()

void UbloxCommandBase::setClassId	(	uint8_t	msgClass,
		uint8_t	msgId
	)

When sending a message, sets the message class and ID.

Parameters

msgClass	The class of the message
msgId	The ID of the message

◆ setData()

bool UbloxCommandBase::setData	(	size_t	offset,
		const void *	data,
		size_t	dataLen
	)

Set data in the buffer.

Parameters

offset	The offset to write to. This is relative to the data payload, so 0 is the first byte of payload data (not the sync byte)
data	Pointer to the data to copy from.
dataLen	The length of the data in bytes.

Returns: true if it was copied or false if not

The data will be copied only if it will fit in the buffer entirely. The data will never be truncated. The payloadLen will be increased if necessary so the data fits within the payloadLen.

◆ setI1()

bool UbloxCommandBase::setI1	(	size_t	offset,
		int8_t	value
	)

inline

Set a int8_t value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setI2()

bool UbloxCommandBase::setI2	(	size_t	offset,
		int16_t	value
	)

inline

Set an int16_t value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setI4()

bool UbloxCommandBase::setI4	(	size_t	offset,
		int32_t	value
	)

inline

Set an int16_t value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setR4()

bool UbloxCommandBase::setR4	(	size_t	offset,
		float	value
	)

inline

Set an float (4 byte floating point) value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setR8()

bool UbloxCommandBase::setR8	(	size_t	offset,
		double	value
	)

inline

Set an double (8 byte floating point) value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setU1()

bool UbloxCommandBase::setU1	(	size_t	offset,
		uint8_t	value
	)

inline

Set a uint8_t value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setU2()

bool UbloxCommandBase::setU2	(	size_t	offset,
		uint16_t	value
	)

inline

Set a uint16_t value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ setU4()

bool UbloxCommandBase::setU4	(	size_t	offset,
		uint32_t	value
	)

inline

Set a uint32_t value at offset in the payload.

Parameters

offset	The offset relative to the payload, so 0 is the first byte of the payload
value	The value to set

The data must fit in the underlying buffer or false will be returned if it can't fit in its entirety. A partial value will never be copied. If the new data is larger than the current payloadLen, then the payload size is increased so it will contain the newly set data.

◆ updateChecksum()

void UbloxCommandBase::updateChecksum ( )

When preparing a command to send, updates the checksum, sync, and length bytes.

The length is generated from the payloadLen member variable, which should be correct when using the set or append methods, or after manually setting the length.

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

src/UbloxGPS.h
src/UbloxGPS.cpp

Public Member Functions

Protected Types

Protected Attributes

Static Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ State

Constructor & Destructor Documentation

◆ UbloxCommandBase()

Member Function Documentation

◆ addHandler()

◆ appendData()

◆ appendI1()

◆ appendI2()

◆ appendI4()

◆ appendR4()

◆ appendR8()

◆ appendU1()

◆ appendU2()

◆ appendU4()

◆ calculateChecksum()

◆ decode()

◆ fillData()

◆ getBuffer()

◆ getData() [1/2]

◆ getData() [2/2]

◆ getI1()

◆ getI2()

◆ getI4()

◆ getMsgClass()

◆ getMsgId()

◆ getR4()

◆ getR8()

◆ getSendLength()

◆ getU1()

◆ getU2()

◆ getU4()

◆ removeHandler()

◆ setClassId()

◆ setData()

◆ setI1()

◆ setI2()

◆ setI4()

◆ setR4()

◆ setR8()

◆ setU1()

◆ setU2()

◆ setU4()

◆ updateChecksum()