TWI - Two-Wire Interface

See Quick start guide for MEGARF TWI driver.

Driver for the Two-Wire Interface (TWI). Provides functions for configuring and using the TWI in both master and slave mode.

Quick start guide

See Quick start guide for MEGARF TWI driver

Modules
	Related Project(s)
	In this section you can find all the projects related to the TWI - Two-Wire Interface.
	Quick Start Guide(s)
	In this section you can find a list of all Quick Start guides related to the TWI - Two-Wire Interface.
	twi master Driver
	This driver is the implementation of TWI module of megaRF device as master.
	twi slave Driver
	This driver is the implementation of TWI module of megaRF device as slave.

Data Structures
struct	slave_data_buffer_t
	TWI Slave data buffers. More...
struct	twi_master_options_t
	Input parameters when initializing the twi master mode. More...
struct	twi_package_t
	Information concerning the data transmission. More...

Macros
#define	TWI_CLOCK_RATE(F_CPU, TWI_SPEED)
	Baud rate register setting calculation. More...
#define	TWI_IDLE   1
#define	TWI_PRESCALE_REG   TWI_TWSR_PRESCALE0
	TWI prescale register value. More...
#define	TWI_PRESCALER   1
#define	TWI_PROCESS   8
#define	TWI_READ_DATA   5
#define	TWI_READ_ENABLE(SDA)   ((SDA & 0xFE) | 0x01)
	TWI Read Enable. More...
#define	TWI_STATUS_IO_ERROR   -1
#define	TWI_STATUS_NO_STATE   1
#define	TWI_STATUS_PROTOCOL_ERROR   -2
#define	TWI_STATUS_RX_COMPLETE   3
#define	TWI_STATUS_TX_COMPLETE   2
#define	TWI_SUCCESS   0
#define	TWI_TRANSAC_FAIL   7
#define	TWI_TRANSAC_SUCCESS   6
#define	TWI_TWSR_PRESCALE0   0x00 /* TWI Prescale=1. */
#define	TWI_TWSR_PRESCALE1   0x01 /* TWI Prescale=4. */
#define	TWI_TWSR_PRESCALE2   0x02 /* TWI Prescale=16. */
#define	TWI_TWSR_PRESCALE3   0x03 /* TWI Prescale=64. */
#define	TWI_TWSR_STATUS_MASK   (TWSR & 0xF8)
	TWSR status mask. More...
#define	TWI_WRITE_DATA   4
#define	TWI_WRITE_ENABLE(SDA)   (SDA & 0xFE)
	TWI Write Enable. More...
#define	TWI_WRITE_IADDR_READ_DATA   3
#define	TWI_WRITE_IADDR_WRITE_DATA   2

Enumerations
enum	{   TWS_BUSERROR = 0x00,   TWS_START = 0x08,   TWS_RSTART = 0x10,   TWS_MT_SLA_ACK = 0x18,   TWS_MT_SLA_NACK = 0x20,   TWS_MT_DATA_ACK = 0x28,   TWS_MT_DATA_NACK = 0x30,   TWS_M_ARB_LOST = 0x38,   TWS_MR_SLA_ACK = 0x40,   TWS_MR_SLA_NACK = 0x48,   TWS_MR_DATA_ACK = 0x50,   TWS_MR_DATA_NACK = 0x58,   TWS_ST_SLA_ACK = 0xA8,   TWS_ST_SLA_ACK_M_ARB_LOST = 0xB0,   TWS_ST_DATA_ACK = 0xB8,   TWS_ST_DATA_NACK = 0xC0,   TWS_ST_DATA_ACK_LAST_BYTE = 0xC8,   TWS_SR_SLA_ACK = 0x60,   TWS_SR_SLA_ACK_M_ARB_LOST = 0x68,   TWS_SR_GEN_ACK = 0x70,   TWS_SR_GEN_ACK_M_ARB_LOST = 0x78,   TWS_SR_SLA_DATA_ACK = 0x80,   TWS_SR_SLA_DATA_NACK = 0x88,   TWS_SR_GEN_DATA_ACK = 0x90,   TWS_SR_GEN_DATA_NACK = 0x98,   TWS_SR_STOP_RESTART = 0xA0 }
	TWI status codes. More...
enum	twiInternalAddrSize_t {   TWI_SLAVE_NO_INTERNAL_ADDRESS,   TWI_SLAVE_ONE_BYTE_SIZE,   TWI_SLAVE_TWO_BYTE_SIZE,   TWI_SLAVE_THREE_BYTE_SIZE }
	internal address size More...

Functions
static void	twi_interrupt_disable (void)
	Disables interrupt on TWI. More...
static void	twi_interrupt_enable (void)
	Enables interrupt on TWI. More...
status_code_t	twi_master_get_status (void)
	returns the status of TWI bus More...
status_code_t	twi_master_init (volatile void *twi, twi_master_options_t *opt)
	Inits TWI module as master. More...
status_code_t	twi_master_read (volatile void *twi, const twi_package_t *package)
	Reads the series of bytes from the TWI bus. More...
status_code_t	twi_master_write (volatile void *twi, const twi_package_t *package)
	Perform a TWI master write transfer. More...
static uint8_t	twi_read_byte (void)
	reads the data More...
static void	twi_reset (void)
	Resets the TWI. More...
static void	twi_send_ack (bool ack)
	Enables the ACK/NACK to send for the received data. More...
static void	twi_send_start (void)
	Directs the TWI to send start condition. More...
static void	twi_send_stop (void)
	Directs TWI to send stop condition. More...
status_code_t	twi_slave_init (uint8_t twi_slave_ownadd)
	Initialize TWI as Slave. More...
status_code_t	twi_slave_start (slave_data_buffer_t *package)
	Start the slave Transceiver. More...
int	twi_slave_state_get (void)
	Get the state of TWI transceiver. More...
int	twi_slave_status_get (void)
	Get the Status of TWI transceiver. More...
void	twi_slave_status_reset (void)
	Resets the slave state and status to initial for next transmission/reception. More...
static void	twi_write_byte (uint8_t data)
	writes the data More...

#define TWI_CLOCK_RATE	(		F_CPU,
			TWI_SPEED
	)

Value:

(((F_CPU / \
TWI_SPEED) - 16) / (2 * TWI_PRESCALER))

Baud rate register setting calculation.

Baud register setting calculation.

Formula described in datasheet.

Referenced by main(), run_twi_master_recv_test(), run_twi_master_send_test(), and twi_master_setup().

#define TWI_IDLE   1

Referenced by main(), twi_interrupt_handler(), twi_master_bus_reset(), twi_master_data_write(), twi_master_read_last_byte(), twi_slave_bus_reset(), twi_slave_init(), twi_slave_last_byte_write_done(), twi_slave_start(), and twi_slave_status_reset().

#define TWI_PRESCALE_REG   TWI_TWSR_PRESCALE0

TWI prescale register value.

Referenced by twi_master_init().

#define TWI_PRESCALER   1

#define TWI_PROCESS   8

Referenced by twi_interrupt_handler().

#define TWI_READ_DATA   5

Referenced by twi_master_addr_ack(), twi_master_internal_addr_write(), twi_master_read(), twi_master_read_done(), twi_master_read_last_byte(), twi_master_start(), and twi_master_write_done().

#define TWI_READ_ENABLE

(

SDA

)

((SDA & 0xFE) | 0x01)

TWI Read Enable.

Referenced by twi_master_start().

#define TWI_STATUS_IO_ERROR   -1

Referenced by twi_interrupt_handler().

#define TWI_STATUS_NO_STATE   1

Referenced by main(), twi_slave_init(), and twi_slave_status_reset().

#define TWI_STATUS_PROTOCOL_ERROR   -2

Referenced by twi_interrupt_handler().

#define TWI_STATUS_RX_COMPLETE   3

Referenced by main(), and twi_interrupt_handler().

#define TWI_STATUS_TX_COMPLETE   2

Referenced by main(), and twi_slave_last_byte_write_done().

#define TWI_SUCCESS   0

Referenced by main().

#define TWI_TRANSAC_FAIL   7

#define TWI_TRANSAC_SUCCESS   6

#define TWI_TWSR_PRESCALE0   0x00 /* TWI Prescale=1. */

#define TWI_TWSR_PRESCALE1   0x01 /* TWI Prescale=4. */

#define TWI_TWSR_PRESCALE2   0x02 /* TWI Prescale=16. */

#define TWI_TWSR_PRESCALE3   0x03 /* TWI Prescale=64. */

#define TWI_TWSR_STATUS_MASK   (TWSR & 0xF8)

TWSR status mask.

Referenced by twi_interrupt_handler().

#define TWI_WRITE_DATA   4

Referenced by twi_master_internal_addr_write(), twi_master_start(), twi_master_write(), and twi_master_write_done().

#define TWI_WRITE_ENABLE

(

SDA

)

(SDA & 0xFE)

TWI Write Enable.

Referenced by twi_master_start().

#define TWI_WRITE_IADDR_READ_DATA   3

Referenced by twi_master_read(), twi_master_start(), and twi_master_write_done().

#define TWI_WRITE_IADDR_WRITE_DATA   2

Referenced by twi_master_internal_addr_write(), twi_master_start(), twi_master_write(), and twi_master_write_done().

anonymous enum

TWI status codes.

Enumerator
TWS_BUSERROR
TWS_START
TWS_RSTART
TWS_MT_SLA_ACK
TWS_MT_SLA_NACK
TWS_MT_DATA_ACK
TWS_MT_DATA_NACK
TWS_M_ARB_LOST
TWS_MR_SLA_ACK
TWS_MR_SLA_NACK
TWS_MR_DATA_ACK
TWS_MR_DATA_NACK
TWS_ST_SLA_ACK
TWS_ST_SLA_ACK_M_ARB_LOST
TWS_ST_DATA_ACK
TWS_ST_DATA_NACK
TWS_ST_DATA_ACK_LAST_BYTE
TWS_SR_SLA_ACK
TWS_SR_SLA_ACK_M_ARB_LOST
TWS_SR_GEN_ACK
TWS_SR_GEN_ACK_M_ARB_LOST
TWS_SR_SLA_DATA_ACK
TWS_SR_SLA_DATA_NACK
TWS_SR_GEN_DATA_ACK
TWS_SR_GEN_DATA_NACK
TWS_SR_STOP_RESTART

enum twiInternalAddrSize_t

internal address size

Enumerator
TWI_SLAVE_NO_INTERNAL_ADDRESS
TWI_SLAVE_ONE_BYTE_SIZE
TWI_SLAVE_TWO_BYTE_SIZE
TWI_SLAVE_THREE_BYTE_SIZE

static void twi_interrupt_disable ( void  )

inlinestatic

Disables interrupt on TWI.

Parameters

none.

static void twi_interrupt_enable ( void  )

inlinestatic

Enables interrupt on TWI.

Parameters

none.

Referenced by twi_master_init().

status_code_t twi_master_get_status

(

void

)

returns the status of TWI bus

Parameters

none

References master_transfer.

Referenced by twi_master_read(), and twi_master_write().

status_code_t twi_master_init	(	volatile void *	twi,
		twi_master_options_t *	opt
	)

Inits TWI module as master.

This function is a TWI Master initialisation.

Parameters

opt	twi setting options (see twi_master_options_t)

References twi_master_options_t::baud_reg, cpu_irq_disable, cpu_irq_enable, MASTER, STATUS_OK, twi_interrupt_enable(), twi_mode, and TWI_PRESCALE_REG.

status_code_t twi_master_read	(	volatile void *	twi,
		const twi_package_t *	package
	)

Reads the series of bytes from the TWI bus.

Parameters

package

- Package information and data (see twi_package_t)

References ERR_INVALID_ARG, twi_package_t::length, master_transfer, NULL, OPERATION_IN_PROGRESS, twi_master_busy, twi_master_get_status(), TWI_READ_DATA, twi_send_start(), TWI_SLAVE_NO_INTERNAL_ADDRESS, and TWI_WRITE_IADDR_READ_DATA.

Referenced by main(), and run_twi_master_recv_test().

status_code_t twi_master_write	(	volatile void *	twi,
		const twi_package_t *	package
	)

Perform a TWI master write transfer.

This function is a TWI Master write transaction.

Parameters

package

- Package information and data (see twi_package_t)

References ERR_INVALID_ARG, master_transfer, NULL, OPERATION_IN_PROGRESS, twi_master_busy, twi_master_get_status(), twi_send_start(), TWI_SLAVE_NO_INTERNAL_ADDRESS, TWI_WRITE_DATA, and TWI_WRITE_IADDR_WRITE_DATA.

Referenced by main(), and run_twi_master_send_test().

static uint8_t twi_read_byte ( void  )

inlinestatic

reads the data

Parameters

none.

Returns

byte that was read from the TWI.

Referenced by twi_interrupt_handler().

static void twi_reset ( void  )

inlinestatic

Resets the TWI.

Parameters

none.

Referenced by twi_master_bus_reset(), and twi_slave_bus_reset().

static void twi_send_ack ( bool  ack )

inlinestatic

Enables the ACK/NACK to send for the received data.

Referenced by twi_master_addr_ack(), and twi_master_read_done().

static void twi_send_start ( void  )

inlinestatic

Directs the TWI to send start condition.

Referenced by twi_master_read(), twi_master_write(), and twi_master_write_done().

static void twi_send_stop ( void  )

inlinestatic

Directs TWI to send stop condition.

Referenced by twi_master_data_write(), and twi_master_read_last_byte().

status_code_t twi_slave_init

(

uint8_t

twi_slave_ownadd

)

Initialize TWI as Slave.

Parameters

TWI_ownAddress

- contains Slave own Address

References slave_transfer, STATUS_OK, TWI_IDLE, and TWI_STATUS_NO_STATE.

Referenced by main(), and twi_slave_setup().

status_code_t twi_slave_start

(

slave_data_buffer_t *

package

)

Start the slave Transceiver.

Returns

status_code_t - status of twi slave

References OPERATION_IN_PROGRESS, slave_transfer, STATUS_OK, TWI_IDLE, and twi_slave_status_reset().

Referenced by main().

int twi_slave_state_get

(

void

)

Get the state of TWI transceiver.

Returns

int - state information

References slave_transfer.

Referenced by main().

int twi_slave_status_get

(

void

)

Get the Status of TWI transceiver.

Returns

int - status information

Get the Status of TWI transceiver.

Returns

int - status information

References slave_transfer.

Referenced by main().

void twi_slave_status_reset

(

void

)

Resets the slave state and status to initial for next transmission/reception.

References SLAVE, slave_transfer, TWI_IDLE, twi_mode, twi_slave_enable(), and TWI_STATUS_NO_STATE.

Referenced by twi_Receive_Success(), twi_slave_start(), twi_Transmission_Failure(), and twi_Transmit_Success().

static void twi_write_byte ( uint8_t  data )

inlinestatic

writes the data

Parameters

data	- an byte for sending.

References data.

Referenced by twi_master_data_write(), twi_master_internal_addr_write(), and twi_master_start().