I2C Class Reference

I2C Peripheral Class. More...

#include <i2c.h>

Public Types
enum	Result_t {   I2C_RES_ACK , I2C_RES_NACK , I2C_RES_ARB_LST , I2C_RES_BUSY ,   I2C_RES_ARG }
	Return result types. More...

Public Member Functions
	I2C (int module)
	Constructor for the I2C peripheral module.
void	setup (uint32_t busSpeed)
	Setup the I2C peripheral interface.
void	resetBus ()
	Reset the I2C bus.
Result_t	DoTransaction (I2CTxn_t *pTransaction, bool bRepeatedStart=false)
	Start an I2C transaction.
void	setNumAddressBytes (uint8_t numAddressBytes=1)
	Specify the register address size for a read or write transaction. A number of bytes, from 0 to 3, can be sent to specify an address up to 24-bit (3 bytes): 0 = none, 1 = 8-bits, 2 = 16-bits, 3 = 24-bits.
Result_t	writeReg8 (uint8_t devAddr, uint32_t reg, uint8_t data)
	Write an 8-bit value to a I2C slave device register.
Result_t	readReg8 (uint8_t devAddr, uint32_t reg, uint8_t &data)
	Read an 8-bit value form an I2C slave device register.
Result_t	writeRegN (uint8_t devAddr, 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.
Result_t	readRegN (uint8_t devAddr, 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.

Friends
class	WireIntf

Detailed Description

I2C Peripheral Class.

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 Enumeration Documentation

Result_t

enum I2C::Result_t

Return result types.

Enumerator
I2C_RES_ACK	Acknowledged.
I2C_RES_NACK	Not acknowledged.
I2C_RES_ARB_LST	Arbitration listening.
I2C_RES_BUSY	Bus is busy.
I2C_RES_ARG	Bad argument.

Constructor & Destructor Documentation

I2C()

I2C::I2C

(

int

module

)

Constructor for the I2C peripheral module.

Parameters

module

The I2C module to instantiate (0, 1 or 2)

Member Function Documentation

DoTransaction()

Result_t I2C::DoTransaction	(	I2CTxn_t *	pTransaction,
		bool	bRepeatedStart = false )

Start an I2C transaction.

Execute the transaction pointed to by pTransaction

Parameters

*pTransaction	Pointer to the transaction to execute
bRepeatedStart	Repeat the I2C start sequence

Returns

Result_t

readReg8()

Result_t I2C::readReg8	(	uint8_t	devAddr,
		uint32_t	reg,
		uint8_t &	data )

Read an 8-bit value form an I2C slave device register.

Parameters

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

Returns

Result_t

readRegN()

Result_t I2C::readRegN	(	uint8_t	devAddr,
		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

devAddr	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_t

setNumAddressBytes()

void I2C::setNumAddressBytes ( uint8_t numAddressBytes = 1 )

inline

Specify the register address size for a read or write transaction. A number of bytes, from 0 to 3, can be sent to specify an address up to 24-bit (3 bytes): 0 = none, 1 = 8-bits, 2 = 16-bits, 3 = 24-bits.

If you are using a single I2C device, or all devices use the same address size, this function only needs to be called once. If you have multiple I2C devices with different address/register bit sizes, then this function should be called before each read/write operation for each different device.

Parameters

numAddressBytes

The number of address bytes to send: 0 - 3. The default value is 1 byte.

setup()

void I2C::setup

(

uint32_t

busSpeed

)

Setup the I2C peripheral interface.

Parameters

busSpeed

Target bus speed. It the specified speed cannot be achieved, a lower bus speed may be enabled.

writeReg8()

Result_t I2C::writeReg8	(	uint8_t	devAddr,
		uint32_t	reg,
		uint8_t	data )

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

Parameters

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

Returns

Result_t

writeRegN()

Result_t I2C::writeRegN	(	uint8_t	devAddr,
		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 slave 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

devAddr	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_t

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

• i2c.h