TwoWire Class Reference

Wire interface class. More...

#include <Wire.h>

Public Member Functions
	TwoWire (void)
	Wire Constructor with platform default I2C module.
	TwoWire (int mod)
	Wire Constructor with specified module.
	TwoWire (PinIO scl, PinIO sda)
	Constructor.
void	setClock (uint32_t clockbaud)
	Set baud rate.
void	begin (uint8_t slave_addr=0)
	Initalize the system.
void	end ()
	Turn system off.
void	beginTransmission (uint8_t address)
	Set up a start for writing.
int	endTransmission (bool bStop=true)
	Do a stop with restart.
size_t	write (const uint8_t *pdata, int len)
	Send data to the target device.
size_t	write (char v)
	Send a char to the target device.
size_t	write (uint8_t v)
	Send an int to the target device.
size_t	write (const char *pStr, int len=-1)
	Send a string to the target device.
int	requestFrom (uint8_t address, size_t quantity, bool stop=true)
	Request bytes from the target device.
size_t	available ()
	Check if any bytes are available to read.
size_t	read (uint8_t *pbuf, size_t maxlen)
	Read available data up to maxlen bytes (Not a standard Wire function)
uint8_t	read ()
	Read the next byte from the buffer.
Target functions
void	onReceive (slave_rx_handler *handler)
	Register a Receive callback (Does not work on the BBI2C software interface)
void	onRequest (slave_rq_handler *handler)
	Register a Request callback (Does not work on the BBI2C software interface)
void	setWireTimeout (int timeout_usec=0, bool reset_on_timeout=false)
	Set the completion timeout.
void	clearTimeout ()
	Clear the completion timeout.
bool	getWireTimeoutFlag ()
	Get whether there is a completion timeout set.
Non-standard extensions
void	reset ()
	Reset the I2C system and unhang the bus.
bool	ping (uint8_t addr)
	Check to see if addr exists on this bus.
int	writeRegN (uint8_t dAddr, uint32_t reg, const uint8_t *buf, uint32_t blen)
	Write a number of 8-bit values to an I2C slave to the specified register address.
int	readRegN (uint8_t dAddr, uint32_t reg, uint8_t *buf, uint32_t blen)
	Read a number of 8-bit values from an I2C slave at the specified register address.
int	writeReg8 (uint8_t dAddr, uint32_t reg, uint8_t data)
	Write an 8-bit value to a I2C target device register.
int	readReg8 (uint8_t dAddr, uint32_t reg, uint8_t &data)
	Read an 8-bit value from an I2C target device register.

Detailed Description

Wire interface class.

Constructor & Destructor Documentation

TwoWire() [1/2]

TwoWire::TwoWire

(

int

mod

)

Wire Constructor with specified module.

Parameters

mod	I2C module number

TwoWire() [2/2]

TwoWire::TwoWire	(	PinIO	scl,
		PinIO	sda )

Constructor.

Parameters

scl	SCL pin
sda	SDA pin

If BBI2C is defined, this will automatically use software I2C if the specified pins don't map to a hardware I2C deivce

Member Function Documentation

available()

size_t TwoWire::available

(

)

Check if any bytes are available to read.

Return values

Number

of bytes available in the buffer

begin()

void TwoWire::begin

(

uint8_t

slave_addr = 0

)

Initalize the system.

Parameters

slave_addr

Address of the target device

beginTransmission()

void TwoWire::beginTransmission

(

uint8_t

address

)

Set up a start for writing.

Parameters

address

Address of the target device

endTransmission()

int TwoWire::endTransmission

(

bool

bStop = true

)

Do a stop with restart.

Parameters

bStop

If true, sends a stop message and releases the bus

Return values

0	Success
1	Data too big
2	NACK on address
3	NACK on data
4	Other error
5	Timeout

onReceive()

void TwoWire::onReceive

(

slave_rx_handler *

handler

)

Register a Receive callback (Does not work on the BBI2C software interface)

Parameters

handler

Pointer to the function to call when bytes are received

onRequest()

void TwoWire::onRequest

(

slave_rq_handler *

handler

)

Register a Request callback (Does not work on the BBI2C software interface)

Parameters

handler

Pointer to the function to call when bytes are requested

ping()

bool TwoWire::ping

(

uint8_t

addr

)

Check to see if addr exists on this bus.

Return values

true	if the address exists

read() [1/2]

uint8_t TwoWire::read ( )

inline

Read the next byte from the buffer.

Return values

One	byte of data from the buffer

read() [2/2]

size_t TwoWire::read	(	uint8_t *	pbuf,
		size_t	maxlen )

Read available data up to maxlen bytes (Not a standard Wire function)

Parameters

pbuf	Pointer to a buffer to read bytes into
maxlen	Maximum number of bytes to read

Return values

0	if no read data is available

readReg8()

int TwoWire::readReg8 ( uint8_t dAddr, uint32_t reg, uint8_t & data )

inline

Read an 8-bit value from an I2C target device register.

Parameters

dAddr	Address of I2C device
reg	Register address to read
data	Reference to variable in which to store the register data

Returns

result code.

readRegN()

int TwoWire::readRegN	(	uint8_t	dAddr,
		uint32_t	reg,
		uint8_t *	buf,
		uint32_t	blen )

Read a number of 8-bit values from an I2C slave at the specified register address.

Parameters

dAddr	Address of I2C device
reg	Register address to read
*buf	Pointer to buffer to store received data
blen	Number of bytes to read

Returns

result code.

requestFrom()

int TwoWire::requestFrom	(	uint8_t	address,
		size_t	quantity,
		bool	stop = true )

Request bytes from the target device.

Parameters

address	Address of the target device
quantity	How many bytes to request
stop	Set true to send a stop message and releases the bus when done, otherwise sends a restart

Return values

number

of bytes read

setClock()

void TwoWire::setClock ( uint32_t clockbaud )

inline

Set baud rate.

Parameters

clockbaud

Baud rate (default 200Khz)

setWireTimeout()

void TwoWire::setWireTimeout	(	int	timeout_usec = 0,
		bool	reset_on_timeout = false )

Set the completion timeout.

Parameters

timeout_usec	Timeout in microseconds
reset_on_timeout	Set true to reset the I2C system and unhang the bus upon timeout

write() [1/4]

size_t TwoWire::write ( char v )

inline

Send a char to the target device.

Parameters

v	Character to write

Return values

number

of bytes written

write() [2/4]

size_t TwoWire::write ( const char * pStr, int len = -1 )

inline

Send a string to the target device.

Parameters

pStr	C-style string to send
len	Length of data

Return values

number

of bytes written

write() [3/4]

size_t TwoWire::write	(	const uint8_t *	pdata,
		int	len )

Send data to the target device.

Parameters

pdata	Pointer to data to send
len	Length of data

Return values

number

of bytes written

write() [4/4]

size_t TwoWire::write ( uint8_t v )

inline

Send an int to the target device.

Parameters

v	Integer data to write

Return values

number

of bytes written

writeReg8()

int TwoWire::writeReg8 ( uint8_t dAddr, uint32_t reg, uint8_t data )

inline

Write an 8-bit value to a I2C target device register.

Parameters

dAddr	Address of I2C device
reg	Register address to write
data	Data to write to register

Returns

result code

writeRegN()

int TwoWire::writeRegN	(	uint8_t	dAddr,
		uint32_t	reg,
		const uint8_t *	buf,
		uint32_t	blen )

Write a number of 8-bit values to an I2C slave to the specified register address.

Executing this function will send the following: a start bit, the target device address and read/write bit, the 8-bit data bytes, and finally a stop bit. Note that the address is not incremented with each 8-bit data value.

Parameters

dAddr	Address of I2C device
reg	Register address to write
*buf	Pointer to buffer containing data to write
blen	Number of bytes to write

Returns

result code.

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

• Wire.h