Two Wire Interface master (TWI) peripheral driver. More...

Modules
	TWI peripheral driver configuration

Data Structures
struct	nrfx_twi_t
	Structure for the TWI master driver instance. More...

struct	nrfx_twi_config_t
	Structure for the configuration of the TWI master driver instance. More...

struct	nrfx_twi_xfer_desc_t
	Structure for a TWI transfer descriptor. More...

struct	nrfx_twi_evt_t
	Structure for a TWI event. More...

Macros
#define	NRFX_TWI_INSTANCE(id)
	Macro for creating a TWI master driver instance. More...

#define	NRFX_TWI_DEFAULT_CONFIG
	The default configuration of the TWI master driver instance. More...

#define	NRFX_TWI_FLAG_NO_XFER_EVT_HANDLER (1UL << 2)
	Flag indicating that the interrupt after each transfer will be suppressed, and the event handler will not be called.

#define	NRFX_TWI_FLAG_TX_NO_STOP (1UL << 5)
	Flag indicating that the TX transfer will not end with a stop condition.

#define	NRFX_TWI_FLAG_SUSPEND (1UL << 6)
	Flag indicating that the transfer will be suspended.

#define	NRFX_TWI_XFER_DESC_TX(addr, p_data, length)
	Macro for setting the TX transfer descriptor. More...

#define	NRFX_TWI_XFER_DESC_RX(addr, p_data, length)
	Macro for setting the RX transfer descriptor. More...

#define	NRFX_TWI_XFER_DESC_TXRX(addr, p_tx, tx_len, p_rx, rx_len)
	Macro for setting the TX-RX transfer descriptor. More...

#define	NRFX_TWI_XFER_DESC_TXTX(addr, p_tx, tx_len, p_tx2, tx_len2)
	Macro for setting the TX-TX transfer descriptor. More...

Typedefs
typedef void(*	nrfx_twi_evt_handler_t )(nrfx_twi_evt_t const p_event, void p_context)
	TWI event handler prototype.

Enumerations
enum	nrfx_twi_evt_type_t { NRFX_TWI_EVT_DONE, NRFX_TWI_EVT_ADDRESS_NACK, NRFX_TWI_EVT_DATA_NACK, NRFX_TWI_EVT_OVERRUN, NRFX_TWI_EVT_BUS_ERROR }
	TWI master driver event types. More...

enum	nrfx_twi_xfer_type_t { NRFX_TWI_XFER_TX, NRFX_TWI_XFER_RX, NRFX_TWI_XFER_TXRX, NRFX_TWI_XFER_TXTX }
	TWI master driver transfer types. More...

Functions
nrfx_err_t	nrfx_twi_init (nrfx_twi_t const p_instance, nrfx_twi_config_t const p_config, nrfx_twi_evt_handler_t event_handler, void *p_context)
	Function for initializing the TWI driver instance. More...

void	nrfx_twi_uninit (nrfx_twi_t const *p_instance)
	Function for uninitializing the TWI instance. More...

void	nrfx_twi_enable (nrfx_twi_t const *p_instance)
	Function for enabling the TWI instance. More...

void	nrfx_twi_disable (nrfx_twi_t const *p_instance)
	Function for disabling the TWI instance. More...

nrfx_err_t	nrfx_twi_tx (nrfx_twi_t const p_instance, uint8_t address, uint8_t const p_data, size_t length, bool no_stop)
	Function for sending data to a TWI slave. More...

nrfx_err_t	nrfx_twi_rx (nrfx_twi_t const p_instance, uint8_t address, uint8_t p_data, size_t length)
	Function for reading data from a TWI slave. More...

nrfx_err_t	nrfx_twi_xfer (nrfx_twi_t const p_instance, nrfx_twi_xfer_desc_t const p_xfer_desc, uint32_t flags)
	Function for performing a TWI transfer. More...

bool	nrfx_twi_is_busy (nrfx_twi_t const *p_instance)
	Function for checking the TWI driver state. More...

size_t	nrfx_twi_data_count_get (nrfx_twi_t const *const p_instance)
	Function for getting the transferred data count. More...

uint32_t	nrfx_twi_stopped_event_get (nrfx_twi_t const *p_instance)
	Function for returning the address of a STOPPED TWI event. More...

__STATIC_INLINE nrfx_err_t	nrfx_twi_bus_recover (uint32_t scl_pin, uint32_t sda_pin)
	Function for recovering the bus. More...

Detailed Description

Two Wire Interface master (TWI) peripheral driver.

Macro Definition Documentation

#define NRFX_TWI_DEFAULT_CONFIG

Value:

{ \
 .frequency = (nrf_twi_frequency_t)NRFX_TWI_DEFAULT_CONFIG_FREQUENCY, \
 .scl = 31, \
 .sda = 31, \
 .interrupt_priority = NRFX_TWI_DEFAULT_CONFIG_IRQ_PRIORITY, \
 .hold_bus_uninit = NRFX_TWI_DEFAULT_CONFIG_HOLD_BUS_UNINIT, \
}

The default configuration of the TWI master driver instance.

#define NRFX_TWI_INSTANCE ( id )

Value:

{ \
 .p_twi = NRFX_CONCAT_2(NRF_TWI, id), \
 .drv_inst_idx = NRFX_CONCAT_3(NRFX_TWI, id, _INST_IDX), \
}

Macro for creating a TWI master driver instance.

#define NRFX_TWI_XFER_DESC_RX	(	addr,
		p_data,
		length
	)

Value:

{ \
 .type = NRFX_TWI_XFER_RX, \
 .address = (addr), \
 .primary_length = (length), \
 .secondary_length = 0, \
 .p_primary_buf = (p_data), \
 .p_secondary_buf = NULL, \
}

Macro for setting the RX transfer descriptor.

#define NRFX_TWI_XFER_DESC_TX	(	addr,
		p_data,
		length
	)

Value:

{ \
 .type = NRFX_TWI_XFER_TX, \
 .address = (addr), \
 .primary_length = (length), \
 .secondary_length = 0, \
 .p_primary_buf = (p_data), \
 .p_secondary_buf = NULL, \
}

Macro for setting the TX transfer descriptor.

#define NRFX_TWI_XFER_DESC_TXRX	(	addr,
		p_tx,
		tx_len,
		p_rx,
		rx_len
	)

Value:

{ \
 .type = NRFX_TWI_XFER_TXRX, \
 .address = (addr), \
 .primary_length = (tx_len), \
 .secondary_length = (rx_len), \
 .p_primary_buf = (p_tx), \
 .p_secondary_buf = (p_rx), \
}

Macro for setting the TX-RX transfer descriptor.

#define NRFX_TWI_XFER_DESC_TXTX	(	addr,
		p_tx,
		tx_len,
		p_tx2,
		tx_len2
	)

Value:

{ \
 .type = NRFX_TWI_XFER_TXTX, \
 .address = (addr), \
 .primary_length = (tx_len), \
 .secondary_length = (tx_len2), \
 .p_primary_buf = (p_tx), \
 .p_secondary_buf = (p_tx2), \
}

Macro for setting the TX-TX transfer descriptor.

Enumeration Type Documentation

enum nrfx_twi_evt_type_t

TWI master driver event types.

Enumerator
NRFX_TWI_EVT_DONE	Transfer completed event.
NRFX_TWI_EVT_ADDRESS_NACK	Error event: NACK received after sending the address.
NRFX_TWI_EVT_DATA_NACK	Error event: NACK received after sending a data byte.
NRFX_TWI_EVT_OVERRUN	Error event: The unread data is replaced by new data.
NRFX_TWI_EVT_BUS_ERROR	Error event: An unexpected transition occurred on the bus.

enum nrfx_twi_xfer_type_t

TWI master driver transfer types.

Enumerator
NRFX_TWI_XFER_TX	TX transfer.
NRFX_TWI_XFER_RX	RX transfer.
NRFX_TWI_XFER_TXRX	TX transfer followed by RX transfer with repeated start.
NRFX_TWI_XFER_TXTX	TX transfer followed by TX transfer with repeated start.

Function Documentation

__STATIC_INLINE nrfx_err_t nrfx_twi_bus_recover	(	uint32_t	scl_pin,
		uint32_t	sda_pin
	)

Function for recovering the bus.

This function checks if the bus is not stuck because of a slave holding the SDA line in the low state, and if needed it performs required number of pulses on the SCL line to make the slave release the SDA line. Finally, the function generates a STOP condition on the bus to put it into a known state.

Note: This function can be used only if the TWI driver is uninitialized.

Parameters

[in]	scl_pin	SCL pin number.
[in]	sda_pin	SDA pin number.

Return values

NRFX_SUCCESS	Bus recovery was successful.
NRFX_ERROR_INTERNAL	Bus recovery failed.

size_t nrfx_twi_data_count_get ( nrfx_twi_t const *const p_instance )

Function for getting the transferred data count.

Parameters

[in] p_instance Pointer to the driver instance structure.

Returns: Data count.

void nrfx_twi_disable ( nrfx_twi_t const * p_instance )

Function for disabling the TWI instance.

Parameters

[in] p_instance Pointer to the driver instance structure.

void nrfx_twi_enable ( nrfx_twi_t const * p_instance )

Function for enabling the TWI instance.

Parameters

[in] p_instance Pointer to the driver instance structure.

nrfx_err_t nrfx_twi_init	(	nrfx_twi_t const *	p_instance,
		nrfx_twi_config_t const *	p_config,
		nrfx_twi_evt_handler_t	event_handler,
		void *	p_context
	)

Function for initializing the TWI driver instance.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	p_config	Pointer to the structure with the initial configuration.
[in]	event_handler	Event handler provided by the user. If NULL, blocking mode is enabled.
[in]	p_context	Context passed to event handler.

Return values

NRFX_SUCCESS	Initialization is successful.
NRFX_ERROR_INVALID_STATE	The driver is in invalid state.
NRFX_ERROR_BUSY	Some other peripheral with the same instance ID is already in use. This is possible only if Peripheral Resource Sharing (PRS) module is enabled.

bool nrfx_twi_is_busy ( nrfx_twi_t const * p_instance )

Function for checking the TWI driver state.

Parameters

[in] p_instance TWI instance.

Return values

true	The TWI driver is currently busy performing a transfer.
false	The TWI driver is ready for a new transfer.

nrfx_err_t nrfx_twi_rx	(	nrfx_twi_t const *	p_instance,
		uint8_t	address,
		uint8_t *	p_data,
		size_t	length
	)

Function for reading data from a TWI slave.

The transmission will be stopped when an error occurs. If a transfer is ongoing, the function returns the error code NRFX_ERROR_BUSY.

Note: This function is deprecated. Use nrfx_twi_xfer instead.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	address	Address of a specific slave device (only 7 LSB).
[in]	p_data	Pointer to a receive buffer.
[in]	length	Number of bytes to be received.

Return values

NRFX_SUCCESS	The procedure is successful.
NRFX_ERROR_BUSY	The driver is not ready for a new transfer.
NRFX_ERROR_INTERNAL	An error is detected by hardware.
NRFX_ERROR_INVALID_STATE	TX transaction is suspended on bus.
NRFX_ERROR_DRV_TWI_ERR_OVERRUN	The unread data is replaced by new data.
NRFX_ERROR_DRV_TWI_ERR_ANACK	Negative acknowledgement (NACK) is received after sending the address in polling mode.
NRFX_ERROR_DRV_TWI_ERR_DNACK	Negative acknowledgement (NACK) is received after sending a data byte in polling mode.

uint32_t nrfx_twi_stopped_event_get ( nrfx_twi_t const * p_instance )

Function for returning the address of a STOPPED TWI event.

A STOPPED event can be used to detect the end of a transfer if the NRFX_TWI_FLAG_NO_XFER_EVT_HANDLER option is used.

Parameters

[in] p_instance Pointer to the driver instance structure.

Returns: STOPPED event address.

nrfx_err_t nrfx_twi_tx	(	nrfx_twi_t const *	p_instance,
		uint8_t	address,
		uint8_t const *	p_data,
		size_t	length,
		bool	no_stop
	)

Function for sending data to a TWI slave.

The transmission will be stopped when an error occurs. If a transfer is ongoing, the function returns the error code NRFX_ERROR_BUSY.

Note: This function is deprecated. Use nrfx_twi_xfer instead.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	address	Address of a specific slave device (only 7 LSB).
[in]	p_data	Pointer to a transmit buffer.
[in]	length	Number of bytes to send.
[in]	no_stop	If set, the stop condition is not generated on the bus after the transfer has completed successfully (allowing for a repeated start in the next transfer).

Return values

NRFX_SUCCESS	The procedure is successful.
NRFX_ERROR_BUSY	The driver is not ready for a new transfer.
NRFX_ERROR_INTERNAL	An error is detected by hardware.
NRFX_ERROR_INVALID_STATE	RX transaction is suspended on bus.
NRFX_ERROR_DRV_TWI_ERR_ANACK	Negative acknowledgement (NACK) is received after sending the address in polling mode.
NRFX_ERROR_DRV_TWI_ERR_DNACK	Negative acknowledgement (NACK) is received after sending a data byte in polling mode.

void nrfx_twi_uninit ( nrfx_twi_t const * p_instance )

Function for uninitializing the TWI instance.

Parameters

[in] p_instance Pointer to the driver instance structure.

nrfx_err_t nrfx_twi_xfer	(	nrfx_twi_t const *	p_instance,
		nrfx_twi_xfer_desc_t const *	p_xfer_desc,
		uint32_t	flags
	)

Function for performing a TWI transfer.

The following transfer types can be configured (nrfx_twi_xfer_desc_t::type):

NRFX_TWI_XFER_TXRX - Write operation followed by a read operation (without STOP condition in between).
NRFX_TWI_XFER_TXTX - Write operation followed by a write operation (without STOP condition in between).
NRFX_TWI_XFER_TX - Write operation (with or without STOP condition).
NRFX_TWI_XFER_RX - Read operation (with STOP condition).

Note: TX-RX and TX-TX transfers are supported only in non-blocking mode.

Additional options are provided using the flags parameter:

NRFX_TWI_FLAG_NO_XFER_EVT_HANDLER - No user event handler after transfer completion. In most cases, this also means no interrupt at the end of the transfer.
NRFX_TWI_FLAG_TX_NO_STOP - No stop condition after TX transfer.
NRFX_TWI_FLAG_SUSPEND - Transfer will be suspended. This allows for combining multiple transfers into one transaction. Only transactions with the same direction can be combined. To finish the transaction, call the function without this flag.

Note

Some flag combinations are invalid:

NRFX_TWI_FLAG_TX_NO_STOP with nrfx_twi_xfer_desc_t::type different than NRFX_TWI_XFER_TX

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	p_xfer_desc	Pointer to the transfer descriptor.
[in]	flags	Transfer options (0 for default settings).

Return values

NRFX_SUCCESS	The procedure is successful.
NRFX_ERROR_BUSY	The driver is not ready for a new transfer.
NRFX_ERROR_NOT_SUPPORTED	The provided parameters are not supported.
NRFX_ERROR_INTERNAL	An unexpected transition occurred on the bus.
NRFX_ERROR_INVALID_STATE	Other direction of transaction is suspended on the bus.
NRFX_ERROR_DRV_TWI_ERR_OVERRUN	The unread data is replaced by new data (TXRX and RX)
NRFX_ERROR_DRV_TWI_ERR_ANACK	Negative acknowledgement (NACK) is received after sending the address in polling mode.
NRFX_ERROR_DRV_TWI_ERR_DNACK	Negative acknowledgement (NACK) is received after sending a data byte in polling mode.

Modules

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

Enumeration Type Documentation

Function Documentation