Module for scheduling TWI transactions. More...

Modules
	TWI transaction manager configuration

Data Structures
struct	app_twi_transfer_t
	TWI transfer descriptor. More...

struct	app_twi_transaction_t
	TWI transaction descriptor. More...

struct	app_twi_queue_t
	TWI transaction queue. More...

struct	app_twi_t
	TWI transaction manager instance. More...

Macros
#define	APP_TWI_NO_STOP 0x01
	Flag indicating that a given transfer should not be ended with a stop condition. More...

#define	APP_TWI_WRITE (address, p_data, length, flags) APP_TWI_TRANSFER ( APP_TWI_WRITE_OP (address), p_data, length, flags)
	Macro for creating a write transfer. More...

#define	APP_TWI_READ (address, p_data, length, flags) APP_TWI_TRANSFER ( APP_TWI_READ_OP (address), p_data, length, flags)
	Macro for creating a read transfer. More...

#define	APP_TWI_TRANSFER (_operation, _p_data, _length, _flags)
	Helper macro, should not be used directly. More...

#define	APP_TWI_WRITE_OP (address) (((address) << 1) \| 0)
	Helper macro, should not be used directly.

#define	APP_TWI_READ_OP (address) (((address) << 1) \| 1)
	Helper macro, should not be used directly.

#define	APP_TWI_IS_READ_OP (operation) ((operation) & 1)
	Helper macro, should not be used directly.

#define	APP_TWI_OP_ADDRESS (operation) ((operation) >> 1)
	Helper macro, should not be used directly.

#define	APP_TWI_INSTANCE (twi_idx)
	Macro for creating an instance of the TWI transaction manager. More...

#define	APP_TWI_INIT (p_app_twi, p_twi_config, queue_size, err_code)
	Macro that simplifies the initialization of a TWI transaction manager instance. More...

Typedefs
typedef void(*	app_twi_callback_t )( ret_code_t result, void *p_user_data)
	TWI transaction callback prototype. More...

Functions
ret_code_t	app_twi_init ( app_twi_t p_app_twi, nrf_drv_twi_config_t const p_twi_config, uint8_t queue_size, app_twi_transaction_t const **p_queue_buffer)
	Function for initializing a TWI transaction manager instance. More...

void	app_twi_uninit ( app_twi_t *p_app_twi)
	Function for uninitializing a TWI transaction manager instance. More...

ret_code_t	app_twi_schedule ( app_twi_t p_app_twi, app_twi_transaction_t const p_transaction)
	Function for scheduling a TWI transaction. More...

ret_code_t	app_twi_perform ( app_twi_t p_app_twi, app_twi_transfer_t const p_transfers, uint8_t number_of_transfers, void(*user_function)(void))
	Function for scheduling a transaction and waiting until it is finished. More...

__STATIC_INLINE bool	app_twi_is_idle ( app_twi_t *p_app_twi)
	Function for getting the current state of a TWI transaction manager instance. More...

Detailed Description

Module for scheduling TWI transactions.

Macro Definition Documentation

#define APP_TWI_INIT	(	p_app_twi,
		p_twi_config,
		queue_size,
		err_code
	)

Value:

         
          do
         
         {                                                                   \
        
         static
         
          app_twi_transaction_t
         
          const
         
         * queue_buffer[queue_size + 1]; \
        
         err_code =
         
          app_twi_init
         
         (p_app_twi, p_twi_config,                   \
        
         queue_size, queue_buffer);                 \
        
         }
         
          while
         
         (0)

Macro that simplifies the initialization of a TWI transaction manager instance.

This macro allocates a static buffer for the transaction queue. Therefore, it should be used in only one place in the code for a given instance.

Parameters

[in]	p_app_twi	Pointer to the instance to be initialized.
[in]	p_twi_config	Pointer to the TWI master driver configuration.
	queue_size	Size of the transaction queue (maximum number of pending transactions). See this note .
[out]	err_code	The result of the app_twi_init() function call is written to this parameter.

#define APP_TWI_INSTANCE ( twi_idx )

Value:

         {                                        \
        
         .twi =
         
          NRF_DRV_TWI_INSTANCE
         
         (twi_idx) \
        
         }

Macro for creating an instance of the TWI transaction manager.

Parameters

[in] twi_idx Index of the TWI master driver instance to be utilized by this manager instance.

#define APP_TWI_NO_STOP 0x01

Flag indicating that a given transfer should not be ended with a stop condition.

Use this flag when a stop condition is undesirable between two transfers, for example, when the first transfer is a write that sets an address in the slave device and the second one is a read that fetches certain data using this address. In this case, the second transfer should follow directly after the first transfer, with a repeated start condition instead of a stop and then a new start condition.

#define APP_TWI_READ	(	address,
		p_data,
		length,
		flags
	)	APP_TWI_TRANSFER ( APP_TWI_READ_OP (address), p_data, length, flags)

Macro for creating a read transfer.

Parameters

	address	Slave address.
[in]	p_data	Pointer to the buffer where received data should be placed.
	length	Number of bytes to transfer.
	flags	Transfer flags (see APP_TWI_NO_STOP ).

#define APP_TWI_TRANSFER	(	_operation,
		_p_data,
		_length,
		_flags
	)

Value:

         {                                      \
        
         .p_data    = (uint8_t *)(_p_data), \
        
         .length    = _length,              \
        
         .operation = _operation,           \
        
         .flags     = _flags                \
        
         }

Helper macro, should not be used directly.

#define APP_TWI_WRITE	(	address,
		p_data,
		length,
		flags
	)	APP_TWI_TRANSFER ( APP_TWI_WRITE_OP (address), p_data, length, flags)

Macro for creating a write transfer.

Parameters

	address	Slave address.
[in]	p_data	Pointer to the data to be sent.
	length	Number of bytes to transfer.
	flags	Transfer flags (see APP_TWI_NO_STOP ).

Typedef Documentation

typedef void(* app_twi_callback_t)( ret_code_t result, void *p_user_data)

TWI transaction callback prototype.

Parameters

	result	Result of operation (NRF_SUCCESS on success, otherwise a relevant error code).
[in]	p_user_data	Pointer to user data defined in transaction descriptor.

Function Documentation

ret_code_t app_twi_init	(	app_twi_t *	p_app_twi ,
		nrf_drv_twi_config_t const *	p_twi_config ,
		uint8_t	queue_size ,
		app_twi_transaction_t const **	p_queue_buffer
	)

Function for initializing a TWI transaction manager instance.

This function initializes the utilized TWI master driver instance and prepares the transaction queue.

Note: The queue size is the maximum number of pending transactions not counting the one that is currently realized. This means that for an empty queue with size of, for example, 4 elements, it is possible to schedule up to 5 transactions.

Parameters

[in]	p_app_twi	Pointer to the instance to be initialized.
[in]	p_twi_config	Pointer to the TWI master driver configuration.
	queue_size	Size of the transaction queue (maximum number of pending transactions).
[in]	p_queue_buffer	Pointer to a buffer for queued transactions storage. Due to the queue implementation, the buffer must be big enough to hold queue_size + 1 entries (pointers to transaction descriptors).

Return values

NRF_SUCCESS If initialization was successful. Otherwise, the error code returned by the nrf_drv_twi_init() function is returned.

__STATIC_INLINE bool app_twi_is_idle ( app_twi_t * p_app_twi )

Function for getting the current state of a TWI transaction manager instance.

Parameters

[in] p_app_twi Pointer to the TWI transaction manager instance.

Return values

true	If all scheduled transactions have been finished.
false	Otherwise.

ret_code_t app_twi_perform	(	app_twi_t *	p_app_twi ,
		app_twi_transfer_t const *	p_transfers ,
		uint8_t	number_of_transfers ,
		void(*)(void)	user_function
	)

Function for scheduling a transaction and waiting until it is finished.

This function schedules a transaction that consists of one or more transfers and waits until it is finished.

Parameters

[in]	p_app_twi	Pointer to the TWI transaction manager instance.
[in]	p_transfers	Pointer to an array of transfers to be performed.
	number_of_transfers	Number of transfers to be performed.
	user_function	User-specified function to be called while waiting. NULL if such functionality is not needed.

Return values

NRF_SUCCESS	If the transfers have been successfully realized.
NRF_ERROR_BUSY	If some transfers are already performed (if this function was called from another context).
-	Other error codes mean that the transaction has ended with the error that is specified in the error code.

ret_code_t app_twi_schedule	(	app_twi_t *	p_app_twi ,
		app_twi_transaction_t const *	p_transaction
	)

Function for scheduling a TWI transaction.

The transaction is enqueued and started as soon as the TWI bus is available, thus when all previously scheduled transactions have been finished (possibly immediately).

Parameters

[in]	p_app_twi	Pointer to the TWI transaction manager instance.
[in]	p_transaction	Pointer to the descriptor of the transaction to be scheduled.

Return values

NRF_SUCCESS	If the transaction has been successfully scheduled.
NRF_ERROR_BUSY	If the limit of pending transactions has been reached (the transaction queue is full).

void app_twi_uninit ( app_twi_t * p_app_twi )

Function for uninitializing a TWI transaction manager instance.

Parameters

[in] p_app_twi Pointer to the instance to be uninitialized.

Modules

Data Structures

Macros

Typedefs

Functions

Detailed Description

Macro Definition Documentation

Typedef Documentation

Function Documentation