The section describes the programming interface of the LPUART Peripheral driver. More...

Data Structures
struct	lpuart_state_t
	Runtime state of the LPUART driver. More...

LPUART Driver
status_t	lpuart_init (uint32_t lpuartInstance, const lpuart_user_config_t lpuartUserConfig, lpuart_state_t lpuartState)
	Initialize a LPUART instance for operation. More...

status_t	lpuart_send_data (lpuart_state_t lpuartState, uint8_t sendBuffer, uint32_t txByteCount, uint32_t timeout)
	Send data out through the LPUART module using a blocking method. More...

status_t	lpuart_send_data_async (lpuart_state_t lpuartState, uint8_t sendBuffer, uint32_t txByteCount)
	Send data out through the LPUART module using a non-blocking method. More...

status_t	lpuart_get_transmit_status (lpuart_state_t lpuartState, uint32_t bytesTransmitted)
	Returns whether the previous transmit has finished yet. More...

status_t	lpuart_get_receive_status (lpuart_state_t lpuartState, uint32_t bytesReceived)
	Returns whether the previous receive has finished yet. More...

void	lpuart_shutdown (lpuart_state_t *lpuartState)
	Shutdown the lpuart by disabling interrupts and transmitter/receiver. More...

status_t	lpuart_receive_data (lpuart_state_t lpuartState, uint8_t rxBuffer, uint32_t requestedByteCount, uint32_t timeout)
	Get data from the LPUART module using a blocking method. More...

status_t	lpuart_receive_data_async (lpuart_state_t lpuartState, uint8_t rxBuffer, uint32_t requestedByteCount)
	Get data from the LPUART module using a non-blocking method. More...

status_t	lpuart_abort_sending_data (lpuart_state_t *lpuartState)
	Terminates an asynchronous transmission early. More...

status_t	lpuart_abort_receiving_data (lpuart_state_t *lpuartState)
	Terminates an asynchronous receive early. More...

LPUART Peripheral Driver

Overview

The LPUART peripheral driver transfers data to and from external devices on the Low Power Universal Asynchronous Receiver/Transmitter (LPUART) serial bus. It provides a way to transmit or receive buffers of data with calls to a single function.

Device structures

The driver uses instantiations of the lpuart_tx_state_t and the lpuart_rx_state_t structure to maintain the current state of a particular LPUART instance module driver. The caller provides memory for the driver state structures during the initialization as the driver itself does not statically allocate memory. The structures are provided below:

// Runtime transmit state of the LPUART driver.
typedef struct LpuartTxState {
    uint32_t instance;                  
    bool isTransmitInProgress;          
    bool isTransmitAsync;               
    const uint8_t * sendBuffer;         
    size_t remainingSendByteCount;      
    size_t transmittedByteCount;        
    sync_object_t irqSync;              
    uint8_t fifoEntryCount;             
} lpuart_tx_state_t;
// Runtime receive state of the LPUART driver.
typedef struct LpuartRxState {
    uint32_t instance;                  
    bool isReceiveInProgress;           
    bool isReceiveAsync;                
    uint8_t * receiveBuffer;            
    size_t remainingReceiveByteCount;   
    size_t receivedByteCount;           
    sync_object_t irqSync;              
    uint8_t fifoEntryCount;             
} lpuart_rx_state_t;

Initialization

To initialize the LPUART driver, call the lpuart_init() function and pass the instance number of the LPUART peripheral you want to use. For instance, to use LPUART0 pass a value of 0 to the initialization function. In addition, you also have to pass a user configuration structure lpuart_user_config_t shown here:

// LPUART configuration structure for user
typedef struct LpuartUserConfig {
    uint32_t baudRate;            
    lpuart_parity_mode_t parityMode;     
    lpuart_stop_bit_count_t stopBitCount; 
    lpuart_bit_count_per_char_t bitCountPerChar; 
} lpuart_user_config_t;

Typically the user configures the lpuart_user_config_t instantiation as an 8-bit-char, no-parity, 1-stop-bit (8-n-1) with a baud rate of 9600 bps. The user can easily modify the lpuart_user_config_t instantiation to configure the LPUART peripheral to a different baud rate or character transfer features. This is a code example to set up a user LPUART configuration instantiation:

lpuart_user_config_t lpuartConfig;
lpuartConfig.baudRate = 9600;
lpuartConfig.bitCountPerChar = kLpuart8BitsPerChar;
lpuartConfig.parityMode = kLpuartParityDisabled;
lpuartConfig.stopBitCount = kLpuartOneStopBit;

Transfers

The driver implements transmit and receive functions to transfer buffers of data. The driver supports two different modes for transferring data: blocking and non-blocking.The blocking transmit and receive functions are the lpuart_send_data() and the lpuart_receive_data().The non-blocking (async) transmit and receive functions are the lpuart_send_data_async() and the lpuart_receive_data_async().In all of these cases, the functions are interrupt driven.

Data Structure Documentation

struct lpuart_state_t

Note, the caller provides memory for the driver state structures during init as the

driver does not statically allocate memory.

Data Fields
uint32_t	instance
	LPUART module instance number.

bool	isTransmitInProgress
	True if there is an active transmit. More...

bool	isTransmitAsync
	Whether the transmit is asynchronous. More...

const uint8_t *	sendBuffer
	The buffer of data being sent. More...

size_t	remainingSendByteCount
	The remaining number of bytes to be transmitted. More...

size_t	transmittedByteCount
	Number of bytes transmitted so far. More...

bool	isReceiveInProgress
	True if there is an active receive. More...

bool	isReceiveAsync
	Whether the receive is asynchronous. More...

uint8_t *	receiveBuffer
	The buffer of received data. More...

size_t	remainingReceiveByteCount
	The remaining number of bytes to be received. More...

size_t	receivedByteCount
	Number of bytes received so far. More...

sync_object_t	txIrqSync
	Used to wait for ISR to complete its tx business. More...

sync_object_t	rxIrqSync
	Used to wait for ISR to complete its rx business. More...

uint8_t	txFifoEntryCount
	Number of data word entries in tx FIFO.

uint8_t	rxFifoEntryCount
	Number of data word entries in rx FIFO.

Field Documentation

bool lpuart_state_t::isTransmitInProgress

bool lpuart_state_t::isTransmitAsync

const uint8_t* lpuart_state_t::sendBuffer

size_t lpuart_state_t::remainingSendByteCount

size_t lpuart_state_t::transmittedByteCount

bool lpuart_state_t::isReceiveInProgress

bool lpuart_state_t::isReceiveAsync

uint8_t* lpuart_state_t::receiveBuffer

size_t lpuart_state_t::remainingReceiveByteCount

size_t lpuart_state_t::receivedByteCount

sync_object_t lpuart_state_t::txIrqSync

sync_object_t lpuart_state_t::rxIrqSync

Function Documentation

status_t lpuart_init	(	uint32_t	lpuartInstance,
		const lpuart_user_config_t *	lpuartUserConfig,
		lpuart_state_t *	lpuartState
	)

   The caller provides memory for the driver state structures during init.

Parameters

lpuartInstance	LPUART instance number
lpuartUserConfig	user configuration structure of type lpuart_user_config_t
lpuartState	Pointer to the LPUART driver state structure

Returns: An error code or kStatus_Success

status_t lpuart_send_data	(	lpuart_state_t *	lpuartState,
		uint8_t *	sendBuffer,
		uint32_t	txByteCount,
		uint32_t	timeout
	)

By blocking, this means that the function will not return until the transmit is complete.

Parameters

lpuartState	Pointer to the LPUART driver state structure
sendBuffer	source buffer containing 8-bit data chars to send
txByteCount	the number of bytes to send
timeout	timeout value for RTOS abstraction sync control

Returns: An error code or kStatus_Success

status_t lpuart_send_data_async	(	lpuart_state_t *	lpuartState,
		uint8_t *	sendBuffer,
		uint32_t	txByteCount
	)

This allows an async method for transmitting data and when coupled with a non-blocking receive, the LPUART can perform a full duplex operation. By non-blocking, this means that the function will return immediately. The application will have to get the transmit status to see when the transmit is complete.

Parameters

lpuartState	Pointer to the LPUART driver state structure
sendBuffer	source buffer containing 8-bit data chars to send
txByteCount	the number of bytes to send

Returns: An error code or kStatus_Success

status_t lpuart_get_transmit_status	(	lpuart_state_t *	lpuartState,
		uint32_t *	bytesTransmitted
	)

Parameters

lpuartState	Pointer to the LPUART driver state structure
bytesTransmitted	Pointer to value that will be filled in with the number of bytes that have been sent in the active transfer

Return values

kStatus_Success	The transmit has completed successfully.
kStatus_LPUART_TxBusy	The transmit is still in progress. bytesTransmitted will be filled with the number of bytes that have been transmitted so far.

status_t lpuart_get_receive_status	(	lpuart_state_t *	lpuartState,
		uint32_t *	bytesReceived
	)

Parameters

lpuartState	Pointer to the LPUART driver state structure
bytesReceived	Pointer to value that will be filled in with the number of bytes that have been received in the active transfer

Return values

kStatus_Success	The receive has completed successfully.
kStatus_LPUART_RxBusy	The receive is still in progress. bytesReceived will be filled with the number of bytes that have been received so far.

void lpuart_shutdown ( lpuart_state_t * lpuartState )

Parameters

lpuartState Pointer to the LPUART driver state structure

status_t lpuart_receive_data	(	lpuart_state_t *	lpuartState,
		uint8_t *	rxBuffer,
		uint32_t	requestedByteCount,
		uint32_t	timeout
	)

By blocking, this means that the function will not return until the receive is complete.

Parameters

lpuartState	Pointer to the LPUART driver state structure
rxBuffer	buffer containing 8-bit read data chars received
requestedByteCount	the number of bytes to receive
timeout	timeout value for RTOS abstraction sync control

Returns: An error code or kStatus_Success

status_t lpuart_receive_data_async	(	lpuart_state_t *	lpuartState,
		uint8_t *	rxBuffer,
		uint32_t	requestedByteCount
	)

This allows an async method for receiving data and when coupled with a non-blocking transmit, the LPUART can perform a full duplex operation. By non-blocking, this means that the function will return immediately. The application will have to get the receive status to see when the receive is complete.

Parameters

lpuartState	Pointer to the LPUART driver state structure
rxBuffer	buffer containing 8-bit read data chars received
requestedByteCount	the number of bytes to receive

Returns: An error code or kStatus_Success

status_t lpuart_abort_sending_data ( lpuart_state_t * lpuartState )

Parameters

lpuartState Pointer to the LPUART driver state structure

Return values

#kStatus_Success The transmit was successful.

status_t lpuart_abort_receiving_data ( lpuart_state_t * lpuartState )

Parameters

lpuartState Pointer to the LPUART driver state structure

Return values

#kStatus_Success The receive was successful.

Data Structures

LPUART Driver

LPUART Peripheral Driver

Overview

Device structures

Initialization

Transfers

Data Structure Documentation

Data Fields

Field Documentation

Function Documentation