WireIntf Class Reference

Wire Interface Class for I2C. More...

#include <i2c.h>

Public Member Functions
void	begin ()
	Initialize the WireIntf driver object as a master with a bus speed of 100 kHz. This normally only needs to be called once.
uint32_t	requestFrom (uint8_t addr, uint32_t len, bool stop=true)
	Request a number of bytes from a slave device. The bytes can then be retrieved from the slave device with the read() and available() functions.
void	beginTransmission (uint8_t addr)
	Begin a transmission to a I2C slave device at the provided address. Bytes can be queued for transmission with the write() functions, and are transmitted by calling endTransmission().
void	endTransmission (bool stop=true)
	Transmits the bytes of data queued by using the write() functions, and ends a transmission to a slave device that was started using beginTransmission().
uint32_t	write (uint8_t dat)
	Queues bytes of data to be transmitted to the slave device. This function can be called after a call to beginTransmission(). The data will not be transmitted on the I2C bus until a call to endTransmission() or flush() is performed.
uint32_t	write (char *str)
	Queues bytes of data to be transmitted to the slave device. This function can be called after a call to beginTransmission(). The data will not be transmitted on the I2C bus until a call to endTransmission() or flush() is performed.
uint32_t	write (uint8_t *buf, uint32_t len)
	Queues bytes of data to be transmitted to the slave device. This function can be called after a call to beginTransmission(). The data will not be transmitted on the I2C bus until a call to endTransmission() or flush() is performed.
uint32_t	available ()
	Get the number of bytes available to be read from the slave device with read(). This function can be called after a call to requestFrom().
uint8_t	read ()
	Reads a byte of data that was transmitted from a slave I2C device after a call to requestFrom().
void	flush (bool bIssueStop=false)
	Force the data that were queued to be transmitted using the write() functions to be transmitted on the I2C bus.

Detailed Description

Wire Interface Class for I2C.

For I2C communication, you can choose the WireIntf class, or the I2C class. The WireIntf class is simpler to use, while the I2C class provides more low level control.

Note that the system automatically instantiates I2C and WireIntf objects for each of the I2C peripheral modules. The WireIntf objects can be accessed with: Wire, Wire1 and Wire2. The I2C objects can be accesses with I2C[0], I2C[1] and I2C[2].

Member Function Documentation

available()

uint32_t WireIntf::available

(

)

Get the number of bytes available to be read from the slave device with read(). This function can be called after a call to requestFrom().

Returns

The number of bytes available for reading from the slave device.

beginTransmission()

void WireIntf::beginTransmission

(

uint8_t

addr

)

Begin a transmission to a I2C slave device at the provided address. Bytes can be queued for transmission with the write() functions, and are transmitted by calling endTransmission().

Parameters

addr	the address of the device to transmit data to.

endTransmission()

void WireIntf::endTransmission

(

bool

stop = true

)

Transmits the bytes of data queued by using the write() functions, and ends a transmission to a slave device that was started using beginTransmission().

Parameters

stop	If true, sends a stop message after the request, releasing the I2C bus. If false, the driver will send a restart request, keeping the connection alive. This prevents other I2C master devices from transmitting between messages. This allows one master to transmit multiple transmissions uninterrupted.

flush()

void WireIntf::flush

(

bool

bIssueStop = false

)

Force the data that were queued to be transmitted using the write() functions to be transmitted on the I2C bus.

If you need to know exactly when a transaction will occur, call flush(). If accessing a register, be sure to write all address bytes before the call.

Parameters

bIssueStop

If true, sends a stop message after the request, releasing the I2C bus. If false, the driver will send a restart request, keeping the connection alive. This prevents other I2C master devices from transmitting between messages. This allows one master to transmit multiple transmissions uninterrupted.

read()

uint8_t WireIntf::read

(

)

Reads a byte of data that was transmitted from a slave I2C device after a call to requestFrom().

Returns

The byte of data received from the slave I2C device.

requestFrom()

uint32_t WireIntf::requestFrom	(	uint8_t	addr,
		uint32_t	len,
		bool	stop = true )

Request a number of bytes from a slave device. The bytes can then be retrieved from the slave device with the read() and available() functions.

Parameters

addr	the address of the slave to request data from.
len	the number of bytes to request from the slave.
stop	If true, sends a stop message after the request, releasing the I2C bus. If false, the driver will send a restart request, keeping the connection alive. This prevents other I2C master devices from transmitting between messages. This allows one master to transmit multiple transmissions uninterrupted.

Returns

The number of bytes returned from the slave I2C device.

write() [1/3]

uint32_t WireIntf::write

(

char *

str

)

Queues bytes of data to be transmitted to the slave device. This function can be called after a call to beginTransmission(). The data will not be transmitted on the I2C bus until a call to endTransmission() or flush() is performed.

Parameters

str	A string to send as a series of bytes to the I2C slave device.

Returns

The number of of bytes written to the transmit queue buffer.

write() [2/3]

uint32_t WireIntf::write	(	uint8_t *	buf,
		uint32_t	len )

Queues bytes of data to be transmitted to the slave device. This function can be called after a call to beginTransmission(). The data will not be transmitted on the I2C bus until a call to endTransmission() or flush() is performed.

Parameters

buf	An array of data to send as bytes to the I2C slave device.
len	The number of bytes to be written from the buf parameter.

Returns

The number of of bytes written to the transmit queue buffer.

write() [3/3]

uint32_t WireIntf::write

(

uint8_t

dat

)

Queues bytes of data to be transmitted to the slave device. This function can be called after a call to beginTransmission(). The data will not be transmitted on the I2C bus until a call to endTransmission() or flush() is performed.

Parameters

dat	A byte of data to be transmitted to the I2C slave device.

Returns

The number of of bytes written to the transmit queue buffer.

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

• i2c.h