An I2C Master, used for communicating with I2C slave devices. More...

#include <I2C.h>

Inheritance diagram for I2C:

Public Member Functions
	I2C (PinName sda, PinName scl)
	Create an I2C Master interface, connected to the specified pins. More...

void	frequency (int hz)
	Set the frequency of the I2C interface. More...

void	timeout (uint32_t timeout)
	Configure the timeout duration in microseconds for blocking transmission. More...

int	read (int address, char *data, int length, bool repeated=false)
	Read from an I2C slave. More...

int	read (int ack)
	Read a single byte from the I2C bus. More...

int	write (int address, const char *data, int length, bool repeated=false)
	Write to an I2C slave. More...

int	write (int data)
	Write single byte out on the I2C bus. More...

void	start (void)
	Creates a start condition on the I2C bus. More...

void	stop (void)
	Creates a stop condition on the I2C bus. More...

virtual void	lock (void)
	Acquire exclusive access to this I2C bus. More...

virtual void	unlock (void)
	Release exclusive access to this I2C bus. More...

int	transfer (int address, const char tx_buffer, int tx_length, char rx_buffer, int rx_length, const event_callback_t &callback, int event=I2C_EVENT_TRANSFER_COMPLETE, bool repeated=false)
	Start nonblocking I2C transfer. More...

void	abort_transfer ()
	Abort the ongoing I2C transfer. More...

Detailed Description

An I2C Master, used for communicating with I2C slave devices.

Note: Synchronization level: Thread safe

Example:

Read temperature from LM75BD
#include "mbed.h"
I2C i2c(I2C_SDA , I2C_SCL);
const int addr7bit = 0x48;      // 7-bit I2C address
const int addr8bit = 0x48 << 1; // 8-bit I2C address, 0x90
int main() {
    char cmd[2];
    while (1) {
        cmd[0] = 0x01;
        cmd[1] = 0x00;
        // read and write takes the 8-bit version of the address.
        // set up configuration register (at 0x01)
        i2c.write(addr8bit, cmd, 2);
        wait(0.5);
        // read temperature register
        cmd[0] = 0x00;
        i2c.write(addr8bit, cmd, 1);
        i2c.read( addr8bit, cmd, 2);
        float tmp = (float((cmd[0]<<8)|cmd[1]) / 256.0);
        printf("Temp = %.2f\n", tmp);
  }
}

Definition at line 82 of file I2C.h.

Constructor & Destructor Documentation

I2C	(	PinName	sda,
		PinName	scl
	)

Create an I2C Master interface, connected to the specified pins.

Parameters

sda	I2C data line pin
scl	I2C clock line pin

Member Function Documentation

void abort_transfer ( )

Abort the ongoing I2C transfer.

void frequency ( int hz )

Set the frequency of the I2C interface.

Parameters

hz	The bus frequency in hertz

virtual void lock ( void )

virtual

Acquire exclusive access to this I2C bus.

int read	(	int	address,
		char *	data,
		int	length,
		bool	repeated = `false`
	)

Read from an I2C slave.

Performs a complete read transaction. The bottom bit of the address is forced to 1 to indicate a read.

Parameters

address	8-bit I2C slave address [ addr \| 1 ]
data	Pointer to the byte-array to read data in to
length	Number of bytes to read
repeated	Repeated start, true - don't send stop at end default value is false.

Returns: 0 on success (ack), nonzero on failure (nack)

int read ( int ack )

Read a single byte from the I2C bus.

Parameters

ack	indicates if the byte is to be acknowledged (1 = acknowledge)

Returns: the byte read

void start ( void )

Creates a start condition on the I2C bus.

void stop ( void )

Creates a stop condition on the I2C bus.

void timeout ( uint32_t timeout )

Configure the timeout duration in microseconds for blocking transmission.

Parameters

timeout Transmission timeout in microseconds.

Note: If no timeout is set the default timeout is used. Default timeout value is based on I2C frequency. Byte timeout is computed as triple amount of time it would take to send 10bit over I2C and is expressed by the formula: byte_timeout = 3 * (1/frequency * 10 * 1000000)

int transfer	(	int	address,
		const char *	tx_buffer,
		int	tx_length,
		char *	rx_buffer,
		int	rx_length,
		const event_callback_t &	callback,
		int	event = `I2C_EVENT_TRANSFER_COMPLETE`,
		bool	repeated = `false`
	)

Start nonblocking I2C transfer.

This function locks the deep sleep until any event has occurred

Parameters

address	8/10 bit I2C slave address
tx_buffer	The TX buffer with data to be transferred
tx_length	The length of TX buffer in bytes
rx_buffer	The RX buffer, which is used for received data
rx_length	The length of RX buffer in bytes
event	The logical OR of events to modify
callback	The event callback function
repeated	Repeated start, true - do not send stop at end default value is false.

Returns: Zero if the transfer has started, or -1 if I2C peripheral is busy

virtual void unlock ( void )

virtual

Release exclusive access to this I2C bus.

int write	(	int	address,
		const char *	data,
		int	length,
		bool	repeated = `false`
	)

Write to an I2C slave.

Performs a complete write transaction. The bottom bit of the address is forced to 0 to indicate a write.

Parameters

address	8-bit I2C slave address [ addr \| 0 ]
data	Pointer to the byte-array data to send
length	Number of bytes to send
repeated	Repeated start, true - do not send stop at end default value is false.

Returns: 0 on success (ack), nonzero on failure (nack)

int write ( int data )

Write single byte out on the I2C bus.

Parameters

data	data to write out on bus

Returns: '0' - NAK was received '1' - ACK was received, '2' - timeout

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Important Information for this Arm website