Overview

The MCUXpresso SDK provides a peripheral driver for the Universal Asynchronous Receiver/Transmitter (UART) module of MCUXpresso SDK devices.

The UART driver includes functional APIs and transactional APIs.

Functional APIs are used for UART initialization/configuration/operation for the purpose of optimization/customization. Using the functional API requires the knowledge of the UART peripheral and how to organize functional APIs to meet the application requirements. All functional APIs use the peripheral base address as the first parameter. UART functional operation groups provide the functional API set.

Transactional APIs can be used to enable the peripheral quickly and in the application if the code size and performance of transactional APIs can satisfy the requirements. If the code size and performance are critical requirements, see the transactional API implementation and write custom code. All transactional APIs use the uart_handle_t as the second parameter. Initialize the handle by calling the UART_TransferCreateHandle() API.

Transactional APIs support asynchronous transfer, which means that the functions UART_TransferSendNonBlocking() and UART_TransferReceiveNonBlocking() set up an interrupt for data transfer. When the transfer completes, the upper layer is notified through a callback function with the kStatus_UART_TxIdle and kStatus_UART_RxIdle.

Transactional receive APIs support the ring buffer. Prepare the memory for the ring buffer and pass in the start address and size while calling the UART_TransferCreateHandle(). If passing NULL, the ring buffer feature is disabled. When the ring buffer is enabled, the received data is saved to the ring buffer in the background. The UART_TransferReceiveNonBlocking() function first gets data from the ring buffer. If the ring buffer does not have enough data, the function first returns the data in the ring buffer and then saves the received data to user memory. When all data is received, the upper layer is informed through a callback with the kStatus_UART_RxIdle.

If the receive ring buffer is full, the upper layer is informed through a callback with the kStatus_UART_RxRingBufferOverrun. In the callback function, the upper layer reads data out from the ring buffer. If not, existing data is overwritten by the new data.

The ring buffer size is specified when creating the handle. Note that one byte is reserved for the ring buffer maintenance. When creating handle using the following code.

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/uart In this example, the buffer size is 32, but only 31 bytes are used for saving data.

Typical use case

UART Send/receive using a polling method

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/uart

UART Send/receive using an interrupt method

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/uart

UART Receive using the ringbuffer feature

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/uart

UART automatic baud rate detect feature

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/uart

Data Structures
struct	uart_config_t
	UART configuration structure. More...

struct	uart_transfer_t
	UART transfer structure. More...

struct	uart_handle_t
	UART handle structure. More...

Typedefs
typedef void(*	uart_transfer_callback_t )(UART_Type base, uart_handle_t handle, status_t status, void *userData)
	UART transfer callback function. More...

Enumerations
enum	{ kStatus_UART_TxBusy = MAKE_STATUS(kStatusGroup_IUART, 0), kStatus_UART_RxBusy = MAKE_STATUS(kStatusGroup_IUART, 1), kStatus_UART_TxIdle = MAKE_STATUS(kStatusGroup_IUART, 2), kStatus_UART_RxIdle = MAKE_STATUS(kStatusGroup_IUART, 3), kStatus_UART_TxWatermarkTooLarge = MAKE_STATUS(kStatusGroup_IUART, 4), kStatus_UART_RxWatermarkTooLarge = MAKE_STATUS(kStatusGroup_IUART, 5), kStatus_UART_FlagCannotClearManually, kStatus_UART_Error = MAKE_STATUS(kStatusGroup_IUART, 7), kStatus_UART_RxRingBufferOverrun = MAKE_STATUS(kStatusGroup_IUART, 8), kStatus_UART_RxHardwareOverrun = MAKE_STATUS(kStatusGroup_IUART, 9), kStatus_UART_NoiseError = MAKE_STATUS(kStatusGroup_IUART, 10), kStatus_UART_FramingError = MAKE_STATUS(kStatusGroup_IUART, 11), kStatus_UART_ParityError = MAKE_STATUS(kStatusGroup_IUART, 12), kStatus_UART_BaudrateNotSupport, kStatus_UART_BreakDetect = MAKE_STATUS(kStatusGroup_IUART, 14) }
	Error codes for the UART driver. More...

enum	uart_data_bits_t { kUART_SevenDataBits = 0x0U, kUART_EightDataBits = 0x1U }
	UART data bits count. More...

enum	uart_parity_mode_t { kUART_ParityDisabled = 0x0U, kUART_ParityEven = 0x2U, kUART_ParityOdd = 0x3U }
	UART parity mode. More...

enum	uart_stop_bit_count_t { kUART_OneStopBit = 0x0U, kUART_TwoStopBit = 0x1U }
	UART stop bit count. More...

enum	uart_idle_condition_t { kUART_IdleFor4Frames = 0x0U, kUART_IdleFor8Frames = 0x1U, kUART_IdleFor16Frames = 0x2U, kUART_IdleFor32Frames = 0x3U }
	UART idle condition detect. More...

enum	_uart_interrupt_enable
	This structure contains the settings for all of the UART interrupt configurations. More...

enum	_uart_flags { kUART_RxCharReadyFlag = 0x0000000FU, kUART_RxErrorFlag = 0x0000000EU, kUART_RxOverrunErrorFlag = 0x0000000DU, kUART_RxFrameErrorFlag = 0x0000000CU, kUART_RxBreakDetectFlag = 0x0000000BU, kUART_RxParityErrorFlag = 0x0000000AU, kUART_ParityErrorFlag = 0x0094000FU, kUART_RtsStatusFlag = 0x0094000EU, kUART_TxReadyFlag = 0x0094000DU, kUART_RtsDeltaFlag = 0x0094000CU, kUART_EscapeFlag = 0x0094000BU, kUART_FrameErrorFlag = 0x0094000AU, kUART_RxReadyFlag = 0x00940009U, kUART_AgingTimerFlag = 0x00940008U, kUART_DtrDeltaFlag = 0x00940007U, kUART_RxDsFlag = 0x00940006U, kUART_tAirWakeFlag = 0x00940005U, kUART_AwakeFlag = 0x00940004U, kUART_Rs485SlaveAddrMatchFlag = 0x00940003U, kUART_AutoBaudFlag = 0x0098000FU, kUART_TxEmptyFlag = 0x0098000EU, kUART_DtrFlag = 0x0098000DU, kUART_IdleFlag = 0x0098000CU, kUART_AutoBaudCntStopFlag = 0x0098000BU, kUART_RiDeltaFlag = 0x0098000AU, kUART_RiFlag = 0x00980009U, kUART_IrFlag = 0x00980008U, kUART_WakeFlag = 0x00980007U, kUART_DcdDeltaFlag = 0x00980006U, kUART_DcdFlag = 0x00980005U, kUART_RtsFlag = 0x00980004U, kUART_TxCompleteFlag = 0x00980003U, kUART_BreakDetectFlag = 0x00980002U, kUART_RxOverrunFlag = 0x00980001U, kUART_RxDataReadyFlag = 0x00980000U }
	UART status flags. More...

Functions
uint32_t	UART_GetInstance (UART_Type *base)
	Get the UART instance from peripheral base address. More...

Variables
uint32_t	uart_config_t::baudRate_Bps
	UART baud rate. More...

uart_parity_mode_t	uart_config_t::parityMode
	Parity error check mode of this module. More...

uart_data_bits_t	uart_config_t::dataBitsCount
	Data bits count, eight (default), seven.

uart_stop_bit_count_t	uart_config_t::stopBitCount
	Number of stop bits in one frame. More...

uint8_t	uart_config_t::txFifoWatermark
	TX FIFO watermark.

uint8_t	uart_config_t::rxFifoWatermark
	RX FIFO watermark.

bool	uart_config_t::enableAutoBaudRate
	Enable automatic baud rate detection.

bool	uart_config_t::enableTx
	Enable TX.

bool	uart_config_t::enableRx
	Enable RX.

uint8_t *	uart_transfer_t::data
	The buffer of data to be transfer. More...

size_t	uart_transfer_t::dataSize
	The byte count to be transfer. More...

uint8_t *volatile	uart_handle_t::txData
	Address of remaining data to send. More...

volatile size_t	uart_handle_t::txDataSize
	Size of the remaining data to send. More...

size_t	uart_handle_t::txDataSizeAll
	Size of the data to send out. More...

uint8_t *volatile	uart_handle_t::rxData
	Address of remaining data to receive. More...

volatile size_t	uart_handle_t::rxDataSize
	Size of the remaining data to receive. More...

size_t	uart_handle_t::rxDataSizeAll
	Size of the data to receive. More...

uint8_t *	uart_handle_t::rxRingBuffer
	Start address of the receiver ring buffer. More...

size_t	uart_handle_t::rxRingBufferSize
	Size of the ring buffer. More...

volatile uint16_t	uart_handle_t::rxRingBufferHead
	Index for the driver to store received data into ring buffer. More...

volatile uint16_t	uart_handle_t::rxRingBufferTail
	Index for the user to get data from the ring buffer. More...

uart_transfer_callback_t	uart_handle_t::callback
	Callback function. More...

void *	uart_handle_t::userData
	UART callback function parameter. More...

volatile uint8_t	uart_handle_t::txState
	TX transfer state. More...

volatile uint8_t	uart_handle_t::rxState
	RX transfer state.

Driver version
#define	FSL_UART_DRIVER_VERSION (MAKE_VERSION(2, 0, 2))
	UART driver version 2.0.2. More...

Software Reset
static void	UART_SoftwareReset (UART_Type *base)
	Resets the UART using software. More...

Initialization and deinitialization
status_t	UART_Init (UART_Type base, const uart_config_t config, uint32_t srcClock_Hz)
	Initializes an UART instance with the user configuration structure and the peripheral clock. More...

void	UART_Deinit (UART_Type *base)
	Deinitializes a UART instance. More...

void	UART_GetDefaultConfig (uart_config_t *config)
	l More...

status_t	UART_SetBaudRate (UART_Type *base, uint32_t baudRate_Bps, uint32_t srcClock_Hz)
	Sets the UART instance baud rate. More...

static void	UART_Enable (UART_Type *base)
	This function is used to Enable the UART Module. More...

static void	UART_SetIdleCondition (UART_Type *base, uart_idle_condition_t condition)
	This function is used to configure the IDLE line condition. More...

static void	UART_Disable (UART_Type *base)
	This function is used to Disable the UART Module. More...

Status
bool	UART_GetStatusFlag (UART_Type *base, uint32_t flag)
	This function is used to get the current status of specific UART status flag(including interrupt flag). More...

void	UART_ClearStatusFlag (UART_Type *base, uint32_t flag)
	This function is used to clear the current status of specific UART status flag. More...

Interrupts
void	UART_EnableInterrupts (UART_Type *base, uint32_t mask)
	Enables UART interrupts according to the provided mask. More...

void	UART_DisableInterrupts (UART_Type *base, uint32_t mask)
	Disables the UART interrupts according to the provided mask. More...

uint32_t	UART_GetEnabledInterrupts (UART_Type *base)
	Gets enabled UART interrupts. More...

Bus Operations
static void	UART_EnableTx (UART_Type *base, bool enable)
	Enables or disables the UART transmitter. More...

static void	UART_EnableRx (UART_Type *base, bool enable)
	Enables or disables the UART receiver. More...

static void	UART_WriteByte (UART_Type *base, uint8_t data)
	Writes to the transmitter register. More...

static uint8_t	UART_ReadByte (UART_Type *base)
	Reads the receiver register. More...

void	UART_WriteBlocking (UART_Type base, const uint8_t data, size_t length)
	Writes to the TX register using a blocking method. More...

status_t	UART_ReadBlocking (UART_Type base, uint8_t data, size_t length)
	Read RX data register using a blocking method. More...

Transactional
void	UART_TransferCreateHandle (UART_Type base, uart_handle_t handle, uart_transfer_callback_t callback, void *userData)
	Initializes the UART handle. More...

void	UART_TransferStartRingBuffer (UART_Type base, uart_handle_t handle, uint8_t *ringBuffer, size_t ringBufferSize)
	Sets up the RX ring buffer. More...

void	UART_TransferStopRingBuffer (UART_Type base, uart_handle_t handle)
	Aborts the background transfer and uninstalls the ring buffer. More...

size_t	UART_TransferGetRxRingBufferLength (uart_handle_t *handle)
	Get the length of received data in RX ring buffer. More...

status_t	UART_TransferSendNonBlocking (UART_Type base, uart_handle_t handle, uart_transfer_t *xfer)
	Transmits a buffer of data using the interrupt method. More...

void	UART_TransferAbortSend (UART_Type base, uart_handle_t handle)
	Aborts the interrupt-driven data transmit. More...

status_t	UART_TransferGetSendCount (UART_Type base, uart_handle_t handle, uint32_t *count)
	Gets the number of bytes written to the UART TX register. More...

status_t	UART_TransferReceiveNonBlocking (UART_Type base, uart_handle_t handle, uart_transfer_t xfer, size_t receivedBytes)
	Receives a buffer of data using an interrupt method. More...

void	UART_TransferAbortReceive (UART_Type base, uart_handle_t handle)
	Aborts the interrupt-driven data receiving. More...

status_t	UART_TransferGetReceiveCount (UART_Type base, uart_handle_t handle, uint32_t *count)
	Gets the number of bytes that have been received. More...

void	UART_TransferHandleIRQ (UART_Type base, uart_handle_t handle)
	UART IRQ handle function. More...

DMA control functions.
static void	UART_EnableTxDMA (UART_Type *base, bool enable)
	Enables or disables the UART transmitter DMA request. More...

static void	UART_EnableRxDMA (UART_Type *base, bool enable)
	Enables or disables the UART receiver DMA request. More...

FIFO control functions.
static void	UART_SetTxFifoWatermark (UART_Type *base, uint8_t watermark)
	This function is used to set the watermark of UART Tx FIFO. More...

static void	UART_SetRxFifoWatermark (UART_Type *base, uint8_t watermark)
	This function is used to set the watermark of UART Rx FIFO. More...

Auto baud rate detection.
static void	UART_EnableAutoBaudRate (UART_Type *base, bool enable)
	This function is used to set the enable condition of Automatic Baud Rate Detection feature. More...

static bool	UART_IsAutoBaudRateComplete (UART_Type *base)
	This function is used to read if the automatic baud rate detection has finished. More...

Data Structure Documentation

struct uart_config_t

Data Fields
uint32_t	baudRate_Bps
	UART baud rate. More...

uart_parity_mode_t	parityMode
	Parity error check mode of this module. More...

uart_data_bits_t	dataBitsCount
	Data bits count, eight (default), seven.

uart_stop_bit_count_t	stopBitCount
	Number of stop bits in one frame. More...

uint8_t	txFifoWatermark
	TX FIFO watermark.

uint8_t	rxFifoWatermark
	RX FIFO watermark.

bool	enableAutoBaudRate
	Enable automatic baud rate detection.

bool	enableTx
	Enable TX.

bool	enableRx
	Enable RX.

struct uart_transfer_t

Data Fields
uint8_t *	data
	The buffer of data to be transfer. More...

size_t	dataSize
	The byte count to be transfer. More...

struct _uart_handle

Forward declaration of the handle typedef.

Data Fields
uint8_t *volatile	txData
	Address of remaining data to send. More...

volatile size_t	txDataSize
	Size of the remaining data to send. More...

size_t	txDataSizeAll
	Size of the data to send out. More...

uint8_t *volatile	rxData
	Address of remaining data to receive. More...

volatile size_t	rxDataSize
	Size of the remaining data to receive. More...

size_t	rxDataSizeAll
	Size of the data to receive. More...

uint8_t *	rxRingBuffer
	Start address of the receiver ring buffer. More...

size_t	rxRingBufferSize
	Size of the ring buffer. More...

volatile uint16_t	rxRingBufferHead
	Index for the driver to store received data into ring buffer. More...

volatile uint16_t	rxRingBufferTail
	Index for the user to get data from the ring buffer. More...

uart_transfer_callback_t	callback
	Callback function. More...

void *	userData
	UART callback function parameter. More...

volatile uint8_t	txState
	TX transfer state. More...

volatile uint8_t	rxState
	RX transfer state.

Macro Definition Documentation

#define FSL_UART_DRIVER_VERSION (MAKE_VERSION(2, 0, 2))

Typedef Documentation

typedef void(* uart_transfer_callback_t)(UART_Type *base, uart_handle_t *handle, status_t status, void *userData)

Enumeration Type Documentation

anonymous enum

Enumerator
kStatus_UART_TxBusy	Transmitter is busy.
kStatus_UART_RxBusy	Receiver is busy.
kStatus_UART_TxIdle	UART transmitter is idle.
kStatus_UART_RxIdle	UART receiver is idle.
kStatus_UART_TxWatermarkTooLarge	TX FIFO watermark too large.
kStatus_UART_RxWatermarkTooLarge	RX FIFO watermark too large.
kStatus_UART_FlagCannotClearManually	UART flag can't be manually cleared.
kStatus_UART_Error	Error happens on UART.
kStatus_UART_RxRingBufferOverrun	UART RX software ring buffer overrun.
kStatus_UART_RxHardwareOverrun	UART RX receiver overrun.
kStatus_UART_NoiseError	UART noise error.
kStatus_UART_FramingError	UART framing error.
kStatus_UART_ParityError	UART parity error.
kStatus_UART_BaudrateNotSupport	Baudrate is not support in current clock source.
kStatus_UART_BreakDetect	Receiver detect BREAK signal.

enum uart_data_bits_t

Enumerator
kUART_SevenDataBits	Seven data bit.
kUART_EightDataBits	Eight data bit.

enum uart_parity_mode_t

Enumerator
kUART_ParityDisabled	Parity disabled.
kUART_ParityEven	Even error check is selected.
kUART_ParityOdd	Odd error check is selected.

enum uart_stop_bit_count_t

Enumerator
kUART_OneStopBit	One stop bit.
kUART_TwoStopBit	Two stop bits.

enum uart_idle_condition_t

Enumerator
kUART_IdleFor4Frames	Idle for more than 4 frames.
kUART_IdleFor8Frames	Idle for more than 8 frames.
kUART_IdleFor16Frames	Idle for more than 16 frames.
kUART_IdleFor32Frames	Idle for more than 32 frames.

enum _uart_interrupt_enable

enum _uart_flags

This provides constants for the UART status flags for use in the UART functions.

Enumerator
kUART_RxCharReadyFlag	Rx Character Ready Flag.
kUART_RxErrorFlag	Rx Error Detect Flag.
kUART_RxOverrunErrorFlag	Rx Overrun Flag.
kUART_RxFrameErrorFlag	Rx Frame Error Flag.
kUART_RxBreakDetectFlag	Rx Break Detect Flag.
kUART_RxParityErrorFlag	Rx Parity Error Flag.
kUART_ParityErrorFlag	Parity Error Interrupt Flag.
kUART_RtsStatusFlag	RTS_B Pin Status Flag.
kUART_TxReadyFlag	Transmitter Ready Interrupt/DMA Flag.
kUART_RtsDeltaFlag	RTS Delta Flag.
kUART_EscapeFlag	Escape Sequence Interrupt Flag.
kUART_FrameErrorFlag	Frame Error Interrupt Flag.
kUART_RxReadyFlag	Receiver Ready Interrupt/DMA Flag.
kUART_AgingTimerFlag	Aging Timer Interrupt Flag.
kUART_DtrDeltaFlag	DTR Delta Flag.
kUART_RxDsFlag	Receiver IDLE Interrupt Flag.
kUART_tAirWakeFlag	Asynchronous IR WAKE Interrupt Flag.
kUART_AwakeFlag	Asynchronous WAKE Interrupt Flag.
kUART_Rs485SlaveAddrMatchFlag	RS-485 Slave Address Detected Interrupt Flag.
kUART_AutoBaudFlag	Automatic Baud Rate Detect Complete Flag.
kUART_TxEmptyFlag	Transmit Buffer FIFO Empty.
kUART_DtrFlag	DTR edge triggered interrupt flag.
kUART_IdleFlag	Idle Condition Flag.
kUART_AutoBaudCntStopFlag	Auto-baud Counter Stopped Flag.
kUART_RiDeltaFlag	Ring Indicator Delta Flag.
kUART_RiFlag	Ring Indicator Input Flag.
kUART_IrFlag	Serial Infrared Interrupt Flag.
kUART_WakeFlag	Wake Flag.
kUART_DcdDeltaFlag	Data Carrier Detect Delta Flag.
kUART_DcdFlag	Data Carrier Detect Input Flag.
kUART_RtsFlag	RTS Edge Triggered Interrupt Flag.
kUART_TxCompleteFlag	Transmitter Complete Flag.
kUART_BreakDetectFlag	BREAK Condition Detected Flag.
kUART_RxOverrunFlag	Overrun Error Flag.
kUART_RxDataReadyFlag	Receive Data Ready Flag.

Function Documentation

uint32_t UART_GetInstance ( UART_Type * base )

Parameters

base	UART peripheral base address.

Returns: UART instance.

static void UART_SoftwareReset ( UART_Type * base )

inlinestatic

This function resets the transmit and receive state machines, all FIFOs and register USR1, USR2, UBIR, UBMR, UBRC , URXD, UTXD and UTS[6-3]

Parameters

base	UART peripheral base address.

status_t UART_Init	(	UART_Type *	base,
		const uart_config_t *	config,
		uint32_t	srcClock_Hz
	)

This function configures the UART module with user-defined settings. Call the UART_GetDefaultConfig() function to configure the configuration structure and get the default configuration. The example below shows how to use this API to configure the UART.

*  uart_config_t uartConfig;
*  uartConfig.baudRate_Bps = 115200U;
*  uartConfig.parityMode = kUART_ParityDisabled;
*  uartConfig.dataBitsCount = kUART_EightDataBits;
*  uartConfig.stopBitCount = kUART_OneStopBit;
*  uartConfig.txFifoWatermark = 2;
*  uartConfig.rxFifoWatermark = 1;
*  uartConfig.enableAutoBaudrate = false;
*  uartConfig.enableTx = true;
*  uartConfig.enableRx = true;
*  UART_Init(UART1, &uartConfig, 24000000U);
* 

Parameters

base	UART peripheral base address.
config	Pointer to a user-defined configuration structure.
srcClock_Hz	UART clock source frequency in HZ.

Return values

kStatus_Success UART initialize succeed

void UART_Deinit ( UART_Type * base )

This function waits for transmit to complete, disables TX and RX, and disables the UART clock.

Parameters

base	UART peripheral base address.

void UART_GetDefaultConfig ( uart_config_t * config )

Gets the default configuration structure.

This function initializes the UART configuration structure to a default value. The default values are: uartConfig->baudRate_Bps = 115200U; uartConfig->parityMode = kUART_ParityDisabled; uartConfig->dataBitsCount = kUART_EightDataBits; uartConfig->stopBitCount = kUART_OneStopBit; uartConfig->txFifoWatermark = 2; uartConfig->rxFifoWatermark = 1; uartConfig->enableAutoBaudrate = flase; uartConfig->enableTx = false; uartConfig->enableRx = false;

Parameters

config Pointer to a configuration structure.

status_t UART_SetBaudRate	(	UART_Type *	base,
		uint32_t	baudRate_Bps,
		uint32_t	srcClock_Hz
	)

This function configures the UART module baud rate. This function is used to update the UART module baud rate after the UART module is initialized by the UART_Init.

* UART_SetBaudRate(UART1, 115200U, 20000000U);

*

Parameters

base	UART peripheral base address.
baudRate_Bps	UART baudrate to be set.
srcClock_Hz	UART clock source frequency in Hz.

Return values

kStatus_UART_BaudrateNotSupport	Baudrate is not support in the current clock source.
kStatus_Success	Set baudrate succeeded.

static void UART_Enable ( UART_Type * base )

inlinestatic

Parameters

base	UART base pointer.

static void UART_SetIdleCondition	(	UART_Type *	base,
		uart_idle_condition_t	condition
	)

inlinestatic

Parameters

base	UART base pointer.
condition	IDLE line detect condition of the enumerators in _uart_idle_condition.

static void UART_Disable ( UART_Type * base )

inlinestatic

Parameters

base	UART base pointer.

bool UART_GetStatusFlag	(	UART_Type *	base,
		uint32_t	flag
	)

The available status flag can be select from uart_status_flag_t enumeration.

Parameters

base	UART base pointer.
flag	Status flag to check.

Return values

current state of corresponding status flag.

void UART_ClearStatusFlag	(	UART_Type *	base,
		uint32_t	flag
	)

The available status flag can be select from uart_status_flag_t enumeration.

Parameters

base	UART base pointer.
flag	Status flag to clear.

void UART_EnableInterrupts	(	UART_Type *	base,
		uint32_t	mask
	)

This function enables the UART interrupts according to the provided mask. The mask is a logical OR of enumeration members. See _uart_interrupt_enable. For example, to enable TX empty interrupt and RX data ready interrupt, do the following.

* UART_EnableInterrupts(UART1,kUART_TxEmptyEnable | kUART_RxDataReadyEnable);

*

Parameters

base	UART peripheral base address.
mask	The interrupts to enable. Logical OR of _uart_interrupt_enable.

void UART_DisableInterrupts	(	UART_Type *	base,
		uint32_t	mask
	)

This function disables the UART interrupts according to the provided mask. The mask is a logical OR of enumeration members. See _uart_interrupt_enable. For example, to disable TX empty interrupt and RX data ready interrupt do the following.

* UART_EnableInterrupts(UART1,kUART_TxEmptyEnable | kUART_RxDataReadyEnable);

*

Parameters

base	UART peripheral base address.
mask	The interrupts to disable. Logical OR of _uart_interrupt_enable.

uint32_t UART_GetEnabledInterrupts ( UART_Type * base )

This function gets the enabled UART interrupts. The enabled interrupts are returned as the logical OR value of the enumerators _uart_interrupt_enable. To check a specific interrupt enable status, compare the return value with enumerators in _uart_interrupt_enable. For example, to check whether the TX empty interrupt is enabled:

*     uint32_t enabledInterrupts = UART_GetEnabledInterrupts(UART1);
*
*     if (kUART_TxEmptyEnable & enabledInterrupts)
*     {
*         ...
*     }
* 

Parameters

base	UART peripheral base address.

Returns: UART interrupt flags which are logical OR of the enumerators in _uart_interrupt_enable.

static void UART_EnableTx	(	UART_Type *	base,
		bool	enable
	)

inlinestatic

This function enables or disables the UART transmitter.

Parameters

base	UART peripheral base address.
enable	True to enable, false to disable.

static void UART_EnableRx	(	UART_Type *	base,
		bool	enable
	)

inlinestatic

This function enables or disables the UART receiver.

Parameters

base	UART peripheral base address.
enable	True to enable, false to disable.

static void UART_WriteByte	(	UART_Type *	base,
		uint8_t	data
	)

inlinestatic

This function is used to write data to transmitter register. The upper layer must ensure that the TX register is empty or that the TX FIFO has room before calling this function.

Parameters

base	UART peripheral base address.
data	Data write to the TX register.

static uint8_t UART_ReadByte ( UART_Type * base )

inlinestatic

This function is used to read data from receiver register. The upper layer must ensure that the receiver register is full or that the RX FIFO has data before calling this function.

Parameters

base	UART peripheral base address.

Returns: Data read from data register.

void UART_WriteBlocking	(	UART_Type *	base,
		const uint8_t *	data,
		size_t	length
	)

This function polls the TX register, waits for the TX register to be empty or for the TX FIFO to have room and writes data to the TX buffer.

Parameters

base	UART peripheral base address.
data	Start address of the data to write.
length	Size of the data to write.

status_t UART_ReadBlocking	(	UART_Type *	base,
		uint8_t *	data,
		size_t	length
	)

This function polls the RX register, waits for the RX register to be full or for RX FIFO to have data, and reads data from the TX register.

Parameters

base	UART peripheral base address.
data	Start address of the buffer to store the received data.
length	Size of the buffer.

Return values

kStatus_UART_RxHardwareOverrun	Receiver overrun occurred while receiving data.
kStatus_UART_NoiseError	A noise error occurred while receiving data.
kStatus_UART_FramingError	A framing error occurred while receiving data.
kStatus_UART_ParityError	A parity error occurred while receiving data.
kStatus_Success	Successfully received all data.

void UART_TransferCreateHandle	(	UART_Type *	base,
		uart_handle_t *	handle,
		uart_transfer_callback_t	callback,
		void *	userData
	)

This function initializes the UART handle which can be used for other UART transactional APIs. Usually, for a specified UART instance, call this API once to get the initialized handle.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.
callback	The callback function.
userData	The parameter of the callback function.

void UART_TransferStartRingBuffer	(	UART_Type *	base,
		uart_handle_t *	handle,
		uint8_t *	ringBuffer,
		size_t	ringBufferSize
	)

This function sets up the RX ring buffer to a specific UART handle.

When the RX ring buffer is used, data received are stored into the ring buffer even when the user doesn't call the UART_TransferReceiveNonBlocking() API. If data is already received in the ring buffer, the user can get the received data from the ring buffer directly.

Note: When using the RX ring buffer, one byte is reserved for internal use. In other words, if ringBufferSize is 32, only 31 bytes are used for saving data.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.
ringBuffer	Start address of the ring buffer for background receiving. Pass NULL to disable the ring buffer.
ringBufferSize	Size of the ring buffer.

void UART_TransferStopRingBuffer	(	UART_Type *	base,
		uart_handle_t *	handle
	)

This function aborts the background transfer and uninstalls the ring buffer.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.

size_t UART_TransferGetRxRingBufferLength ( uart_handle_t * handle )

Parameters

handle UART handle pointer.

Returns: Length of received data in RX ring buffer.

status_t UART_TransferSendNonBlocking	(	UART_Type *	base,
		uart_handle_t *	handle,
		uart_transfer_t *	xfer
	)

This function sends data using an interrupt method. This is a non-blocking function, which returns directly without waiting for all data to be written to the TX register. When all data is written to the TX register in the ISR, the UART driver calls the callback function and passes the kStatus_UART_TxIdle as status parameter.

Note: The kStatus_UART_TxIdle is passed to the upper layer when all data is written to the TX register. However, it does not ensure that all data is sent out. Before disabling the TX, check the kUART_TransmissionCompleteFlag to ensure that the TX is finished.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.
xfer	UART transfer structure. See uart_transfer_t.

Return values

kStatus_Success	Successfully start the data transmission.
kStatus_UART_TxBusy	Previous transmission still not finished; data not all written to TX register yet.
kStatus_InvalidArgument	Invalid argument.

void UART_TransferAbortSend	(	UART_Type *	base,
		uart_handle_t *	handle
	)

This function aborts the interrupt-driven data sending. The user can get the remainBytes to find out how many bytes are not sent out.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.

status_t UART_TransferGetSendCount	(	UART_Type *	base,
		uart_handle_t *	handle,
		uint32_t *	count
	)

This function gets the number of bytes written to the UART TX register by using the interrupt method.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.
count	Send bytes count.

Return values

kStatus_NoTransferInProgress	No send in progress.
kStatus_InvalidArgument	The parameter is invalid.
kStatus_Success	Get successfully through the parameter `count`;

status_t UART_TransferReceiveNonBlocking	(	UART_Type *	base,
		uart_handle_t *	handle,
		uart_transfer_t *	xfer,
		size_t *	receivedBytes
	)

This function receives data using an interrupt method. This is a non-blocking function, which returns without waiting for all data to be received. If the RX ring buffer is used and not empty, the data in the ring buffer is copied and the parameter receivedBytes shows how many bytes are copied from the ring buffer. After copying, if the data in the ring buffer is not enough to read, the receive request is saved by the UART driver. When the new data arrives, the receive request is serviced first. When all data is received, the UART driver notifies the upper layer through a callback function and passes the status parameter kStatus_UART_RxIdle. For example, the upper layer needs 10 bytes but there are only 5 bytes in the ring buffer. The 5 bytes are copied to the xfer->data and this function returns with the parameter receivedBytes set to 5. For the left 5 bytes, newly arrived data is saved from the xfer->data[5]. When 5 bytes are received, the UART driver notifies the upper layer. If the RX ring buffer is not enabled, this function enables the RX and RX interrupt to receive data to the xfer->data. When all data is received, the upper layer is notified.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.
xfer	UART transfer structure, see uart_transfer_t.
receivedBytes	Bytes received from the ring buffer directly.

Return values

kStatus_Success	Successfully queue the transfer into transmit queue.
kStatus_UART_RxBusy	Previous receive request is not finished.
kStatus_InvalidArgument	Invalid argument.

void UART_TransferAbortReceive	(	UART_Type *	base,
		uart_handle_t *	handle
	)

This function aborts the interrupt-driven data receiving. The user can get the remainBytes to know how many bytes are not received yet.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.

status_t UART_TransferGetReceiveCount	(	UART_Type *	base,
		uart_handle_t *	handle,
		uint32_t *	count
	)

This function gets the number of bytes that have been received.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.
count	Receive bytes count.

Return values

kStatus_NoTransferInProgress	No receive in progress.
kStatus_InvalidArgument	Parameter is invalid.
kStatus_Success	Get successfully through the parameter `count`;

void UART_TransferHandleIRQ	(	UART_Type *	base,
		uart_handle_t *	handle
	)

This function handles the UART transmit and receive IRQ request.

Parameters

base	UART peripheral base address.
handle	UART handle pointer.

static void UART_EnableTxDMA	(	UART_Type *	base,
		bool	enable
	)

inlinestatic

This function enables or disables the transmit request when the transmitter has one or more slots available in the TxFIFO. The fill level in the TxFIFO that generates the DMA request is controlled by the TXTL bits.

Parameters

base	UART peripheral base address.
enable	True to enable, false to disable.

static void UART_EnableRxDMA	(	UART_Type *	base,
		bool	enable
	)

inlinestatic

This function enables or disables the receive request when the receiver has data in the RxFIFO. The fill level in the RxFIFO at which a DMA request is generated is controlled by the RXTL bits .

Parameters

base	UART peripheral base address.
enable	True to enable, false to disable.

static void UART_SetTxFifoWatermark	(	UART_Type *	base,
		uint8_t	watermark
	)

inlinestatic

   A maskable interrupt is generated whenever the data level in
   the TxFIFO falls below the Tx FIFO watermark.

Parameters

base	UART base pointer.
watermark	The Tx FIFO watermark.

static void UART_SetRxFifoWatermark	(	UART_Type *	base,
		uint8_t	watermark
	)

inlinestatic

   A maskable interrupt is generated whenever the data level in
   the RxFIFO reaches the Rx FIFO watermark.

Parameters

base	UART base pointer.
watermark	The Rx FIFO watermark.

static void UART_EnableAutoBaudRate	(	UART_Type *	base,
		bool	enable
	)

inlinestatic

Parameters

base	UART base pointer.
enable	Enable/Disable Automatic Baud Rate Detection feature. true: Enable Automatic Baud Rate Detection feature. false: Disable Automatic Baud Rate Detection feature.

static bool UART_IsAutoBaudRateComplete ( UART_Type * base )

inlinestatic

Parameters

base	UART base pointer.

Returns

- true: Automatic baud rate detection has finished.

false: Automatic baud rate detection has not finished.

Variable Documentation

uint32_t uart_config_t::baudRate_Bps

uart_parity_mode_t uart_config_t::parityMode

uart_stop_bit_count_t uart_config_t::stopBitCount

uint8_t* uart_transfer_t::data

size_t uart_transfer_t::dataSize

uint8_t* volatile uart_handle_t::txData

volatile size_t uart_handle_t::txDataSize

size_t uart_handle_t::txDataSizeAll

uint8_t* volatile uart_handle_t::rxData

volatile size_t uart_handle_t::rxDataSize

size_t uart_handle_t::rxDataSizeAll

uint8_t* uart_handle_t::rxRingBuffer

size_t uart_handle_t::rxRingBufferSize

volatile uint16_t uart_handle_t::rxRingBufferHead

volatile uint16_t uart_handle_t::rxRingBufferTail

uart_transfer_callback_t uart_handle_t::callback

void* uart_handle_t::userData

volatile uint8_t uart_handle_t::txState

Overview

Typical use case

UART Send/receive using a polling method

UART Send/receive using an interrupt method

UART Receive using the ringbuffer feature

UART automatic baud rate detect feature

Data Structures

Typedefs

Enumerations

Functions

Variables

Driver version

Software Reset

Initialization and deinitialization

Status

Interrupts

Bus Operations

Transactional

DMA control functions.

FIFO control functions.

Auto baud rate detection.

Data Structure Documentation

Data Fields

Data Fields

Data Fields

Macro Definition Documentation

Typedef Documentation

Enumeration Type Documentation

Function Documentation

Variable Documentation