I2C Controller Driver

This section covers functions related to the SAM L22's built-I2C driver, including configuring the I2C bus, putting values directly on the bus and reading data from registers on I2C devices. More...

Functions
void	watch_enable_i2c (void)
	Enables the I2C peripheral. Call this before attempting to interface with I2C devices.
void	watch_disable_i2c (void)
	Disables the I2C peripheral.
void	watch_i2c_send (int16_t addr, uint8_t *buf, uint16_t length)
	Sends a series of values to a device on the I2C bus.
void	watch_i2c_receive (int16_t addr, uint8_t *buf, uint16_t length)
	Receives a series of values from a device on the I2C bus.
void	watch_i2c_write8 (int16_t addr, uint8_t reg, uint8_t data)
	Writes a byte to a register in an I2C device.
uint8_t	watch_i2c_read8 (int16_t addr, uint8_t reg)
	Reads a byte from a register in an I2C device.
uint16_t	watch_i2c_read16 (int16_t addr, uint8_t reg)
	Reads an unsigned little-endian word from a register in an I2C device.
uint32_t	watch_i2c_read24 (int16_t addr, uint8_t reg)
	Reads three bytes as an unsigned little-endian int from a register in an I2C device.
uint32_t	watch_i2c_read32 (int16_t addr, uint8_t reg)
	Reads an unsigned little-endian int from a register in an I2C device.

Detailed Description

This section covers functions related to the SAM L22's built-I2C driver, including configuring the I2C bus, putting values directly on the bus and reading data from registers on I2C devices.

Function Documentation

watch_i2c_read16()

uint16_t watch_i2c_read16	(	int16_t	addr,
		uint8_t	reg
	)

Reads an unsigned little-endian word from a register in an I2C device.

Parameters

addr	The address of the device you wish to address.
reg	The register on the device that you wish to read.

Returns

An unsigned word representing the value of the register that was read.

Note

This reads two bytes into the word in bus order. If the device returns the LSB first and then the MSB, you can use this value as returned. If the device returns the data in big-endian order or uses some other kind of fancy bit packing, you may need to shuffle some bits around.

watch_i2c_read24()

uint32_t watch_i2c_read24	(	int16_t	addr,
		uint8_t	reg
	)

Reads three bytes as an unsigned little-endian int from a register in an I2C device.

Parameters

addr	The address of the device you wish to address.
reg	The register on the device that you wish to read.

Returns

An unsigned word representing the value of the register that was read.

Note

This reads three bytes into the word in bus order. If the device returns these bytes LSB first, you can use this value as returned. If there is a sign bit, the device returns the data in big-endian order, or it uses some other kind of fancy bit packing, you may need to shuffle some bits around.

watch_i2c_read32()

uint32_t watch_i2c_read32	(	int16_t	addr,
		uint8_t	reg
	)

Reads an unsigned little-endian int from a register in an I2C device.

Parameters

addr	The address of the device you wish to address.
reg	The register on the device that you wish to read.

Returns

An unsigned word representing the value of the register that was read.

Note

This reads three bytes into the word in bus order. If the device returns these bytes LSB first, you can use this value as returned. If the device returns the data in big-endian order, or it uses some other kind of fancy bit packing, you may need to shuffle some bits around.

watch_i2c_read8()

uint8_t watch_i2c_read8	(	int16_t	addr,
		uint8_t	reg
	)

Reads a byte from a register in an I2C device.

Parameters

addr	The address of the device you wish to address.
reg	The register on the device that you wish to read.

Returns

An unsigned byte representing the value of the register that was read.

watch_i2c_receive()

void watch_i2c_receive	(	int16_t	addr,
		uint8_t *	buf,
		uint16_t	length
	)

Receives a series of values from a device on the I2C bus.

Parameters

addr	The address of the device you wish to hear from.
buf	Storage for the incoming bytes; on return, it will contain the received data.
length	The number of bytes that you wish to receive.

watch_i2c_send()

void watch_i2c_send	(	int16_t	addr,
		uint8_t *	buf,
		uint16_t	length
	)

Sends a series of values to a device on the I2C bus.

Parameters

addr	The address of the device you wish to talk to.
buf	A series of unsigned bytes; the data you wish to transmit.
length	The number of bytes in buf that you wish to send.

watch_i2c_write8()

void watch_i2c_write8	(	int16_t	addr,
		uint8_t	reg,
		uint8_t	data
	)

Writes a byte to a register in an I2C device.

Parameters

addr	The address of the device you wish to address.
reg	The register on the device that you wish to set.
data	The value that you wish to set the register to.