UART module

Macro for safe initialization of the UART module in a single user instance when using a FIFO together with UART.

Parameters

[in]	P_COMM_PARAMS	Pointer to a UART communication structure: app_uart_comm_params_t
[in]	RX_BUF_SIZE	Size of desired RX buffer, must be a power of 2 or ZERO (No FIFO).
[in]	TX_BUF_SIZE	Size of desired TX buffer, must be a power of 2 or ZERO (No FIFO).
[in]	EVT_HANDLER	Event handler function to be called when an event occurs in the UART module.
[in]	IRQ_PRIO	IRQ priority, app_irq_priority_t, for the UART module irq handler.
[out]	ERR_CODE	The return value of the UART initialization function will be written to this parameter.

Note

Since this macro allocates a buffer and registers the module as a GPIOTE user when flow control is enabled, it must only be called once.

Macro for safe initialization of the UART module in a single user instance.

Parameters

[in]	P_COMM_PARAMS	Pointer to a UART communication structure: app_uart_comm_params_t
[in]	EVT_HANDLER	Event handler function to be called when an event occurs in the UART module.
[in]	IRQ_PRIO	IRQ priority, app_irq_priority_t, for the UART module irq handler.
[out]	ERR_CODE	The return value of the UART initialization function will be written to this parameter.

Note

Since this macro allocates registers the module as a GPIOTE user when flow control is enabled, it must only be called once.

Value indicating that no pin is connected to this UART register.

Function for handling app_uart event callback.

Upon an event in the app_uart module this callback function will be called to notify the application about the event.

Parameters

[in]

p_app_uart_event

Pointer to UART event.

Enumeration describing current state of the UART.

The connection state can be fetched by the application using the function call app_uart_get_connection_state . When hardware flow control is used

• APP_UART_CONNECTED: Communication is ongoing.
• APP_UART_DISCONNECTED: No communication is ongoing.

When no hardware flow control is used

• APP_UART_CONNECTED: Always returned as bytes can always be received/transmitted.

Enumeration which defines events used by the UART module upon data reception or error.

The event type is used to indicate the type of additional information in the event app_uart_evt_t .

UART Flow Control modes for the peripheral.

Function for closing the UART module.

This function will close any on-going UART transmissions and disable itself in the GPTIO module.

Parameters

[in]

app_uart_id

User id for the UART module. The app_uart_uid must be identical to the UART id returned on initialization and which is currently in use.

Return values

NRF_SUCCESS	If successfully closed.
NRF_ERROR_INVALID_PARAM	If an invalid user id is provided or the user id differs from the current active user.

Function for flushing the RX and TX buffers (Only valid if FIFO is used). This function does nothing if FIFO is not used.

Return values

NRF_SUCCESS

Flushing completed (Current implementation will always succeed).

Function for getting a byte from the UART.

This function will get the next byte from the RX buffer. If the RX buffer is empty an error code will be returned and the app_uart module will generate an event upon reception of the first byte which is added to the RX buffer.

Parameters

[out]

p_byte

Pointer to an address where next byte received on the UART will be copied.

Return values

NRF_SUCCESS	If a byte has been received and pushed to the pointer provided.
NRF_ERROR_NOT_FOUND	If no byte is available in the RX buffer of the app_uart module.

Function for getting the current state of the UART.

If flow control is disabled, the state is assumed to always be APP_UART_CONNECTED.

     When using flow control the state will be controlled by the CTS. If CTS is set active
     by the remote side, or the app_uart module is in the process of transmitting a byte,
     app_uart is in APP_UART_CONNECTED state. If CTS is set inactive by remote side app_uart
     will not get into APP_UART_DISCONNECTED state until the last byte in the TXD register
     is fully transmitted.

     Internal states in the state machine are mapped to the general connected/disconnected
     states in the following ways:

     - UART_ON    = CONNECTED
     - UART_READY = CONNECTED
     - UART_WAIT  = CONNECTED
     - UART_OFF   = DISCONNECTED.

Parameters

[out]

p_connection_state

Current connection state of the UART.

Return values

NRF_SUCCESS

The connection state was successfully retrieved.

Function for initializing the UART module. Use this initialization when several instances of the UART module are needed.

This initialization will return a UART user id for the caller. The UART user id must be used upon re-initialization of the UART or closing of the module for the user. If single instance usage is needed, the APP_UART_INIT() macro should be used instead.

Note

Normally single instance initialization should be done using the APP_UART_INIT() or APP_UART_INIT_FIFO() macro depending on whether the FIFO should be used by the UART, as that will allocate the buffers needed by the UART module (including aligning the buffer correctly).

Parameters

[in]	p_comm_params	Pin and communication parameters.
[in]	p_buffers	RX and TX buffers, NULL is FIFO is not used.
[in]	error_handler	Function to be called in case of an error.
[in]	irq_priority	Interrupt priority level.
[in,out]	p_uart_uid	User id for the UART module. The p_uart_uid must be used if re-initialization and/or closing of the UART module is needed. If the value pointed to by p_uart_uid is zero, this is considdered a first time initialization. Otherwise this is considered a re-initialization for the user with id *p_uart_uid.

Return values

NRF_SUCCESS	If successful initialization.
NRF_ERROR_INVALID_LENGTH	If a provided buffer is not a power of two.
NRF_ERROR_NULL	If one of the provided buffers is a NULL pointer.

The below errors are propagated by the UART module to the caller upon registration when Hardware Flow Control is enabled. When Hardware Flow Control is not used, these errors cannot occur.

Return values

NRF_ERROR_INVALID_STATE	The GPIOTE module is not in a valid state when registering the UART module as a user.
NRF_ERROR_INVALID_PARAM	The UART module provides an invalid callback function when registering the UART module as a user. Or the value pointed to by *p_uart_uid is not a valid GPIOTE number.
NRF_ERROR_NO_MEM	GPIOTE module has reached the maximum number of users.

Function for putting a byte on the UART.

This call is non-blocking.

Parameters

[in]

byte

Byte to be transmitted on the UART.

Return values

NRF_SUCCESS	If the byte was successfully put on the TX buffer for transmission.
NRF_ERROR_NO_MEM	If no more space is available in the TX buffer. NRF_ERROR_NO_MEM may occur if flow control is enabled and CTS signal is high for a long period and the buffer fills up.