The KSDK provides a peripheral driver for the Universal Asynchronous Receiver/Transmitter (UART) module of Kinetis devices.
The UART driver includes two parts: functional APIs and transactional APIs.
Functional APIs are used for UART initialization/configuration/operation for optimization/customization purpose. Using the functional API requires the knowledge of the UART peripheral and know how to organize functional APIs to meet the application requirements. All functional API use the peripheral base address as the first parameter. UART functional operation groups provide the functional APIs 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 first parameter. Initialize the handle by calling the UART_CreateHandle() API.
Transactional APIs support asynchronous transfer, which means that the functions UART_SendNonBlocking() and UART_ReceiveNonBlocking() 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_CreateHandle(). 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_ReceiveNonBlocking() 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, the oldest 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:
UART_CreateHandle(&handle, UART0, &ringBuffer, 32);
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
uint8_t ch;
user_config.baudRate_Bps = 115200U;
user_config.enableTx = true;
user_config.enableRx = true;
while(1)
{
UART_TransferReceiveBlocking(UART1, &ch, 1);
UART_TransferSendBlocking(UART1, &ch, 1);
}
UART Send/receive using an interrupt method
uart_handle_t g_uartHandle;
volatile bool txFinished;
volatile bool rxFinished;
uint8_t sendData[] = ['H', 'e', 'l', 'l', 'o'];
uint8_t receiveData[32];
void UART_UserCallback(uart_handle_t *handle, status_t status, void *userData)
{
userData = userData;
{
txFinished = true;
}
{
rxFinished = true;
}
}
void main(void)
{
UART_CreateHandle(&g_uartHandle, UART1, NULL, 0);
UART_SetTransferCallback(&g_uartHandle, UART_UserCallback, NULL);
sendXfer.
dataSize =
sizeof(sendData)/
sizeof(sendData[0]);
txFinished = false;
UART_SendNonBlocking(&g_uartHandle, &sendXfer);
while (!txFinished)
{
}
receiveXfer.
data = receiveData;
receiveXfer.
dataSize =
sizeof(receiveData)/
sizeof(receiveData[0]);
rxFinished = false;
UART_ReceiveNonBlocking(&g_uartHandle, &receiveXfer, NULL);
while (!rxFinished)
{
}
}
UART Receive using the ringbuffer feature
#define RING_BUFFER_SIZE 64
#define RX_DATA_SIZE 32
uart_handle_t g_uartHandle;
volatile bool txFinished;
volatile bool rxFinished;
uint8_t receiveData[RX_DATA_SIZE];
uint8_t ringBuffer[RING_BUFFER_SIZE];
void UART_UserCallback(uart_handle_t *handle, status_t status, void *userData)
{
userData = userData;
{
rxFinished = true;
}
}
void main(void)
{
size_t bytesRead;
UART_CreateHandle(&g_uartHandle, UART1, &ringBuffer, RING_BUFFER_SIZE);
UART_SetTransferCallback(&g_uartHandle, UART_UserCallback, NULL);
receiveXfer.
data = receiveData;
rxFinished = false;
UART_ReceiveNonBlocking(&g_uartHandle, &receiveXfer, &bytesRead);
if (bytesRead = RX_DATA_SIZE)
UART Send/Receive using the DMA method
uart_handle_t g_uartHandle;
volatile bool txFinished;
volatile bool rxFinished;
uint8_t sendData[] = ['H', 'e', 'l', 'l', 'o'];
uint8_t receiveData[32];
void UART_UserCallback(uart_handle_t *handle, status_t status, void *userData)
{
userData = userData;
{
txFinished = true;
}
{
rxFinished = true;
}
}
void main(void)
{
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typedef void(* | uart_transfer_callback_t )(UART_Type *base, uart_handle_t *handle, status_t status, void *userData) |
| UART transfer callback function. More...
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enum | _uart_status {
kStatus_UART_TxBusy = MAKE_STATUS(kStatusGroup_UART, 0),
kStatus_UART_RxBusy = MAKE_STATUS(kStatusGroup_UART, 1),
kStatus_UART_TxIdle = MAKE_STATUS(kStatusGroup_UART, 2),
kStatus_UART_RxIdle = MAKE_STATUS(kStatusGroup_UART, 3),
kStatus_UART_TxWatermarkTooLarge = MAKE_STATUS(kStatusGroup_UART, 4),
kStatus_UART_RxWatermarkTooLarge = MAKE_STATUS(kStatusGroup_UART, 5),
kStatus_UART_FlagCannotClearManually,
kStatus_UART_Error = MAKE_STATUS(kStatusGroup_UART, 7),
kStatus_UART_RxRingBufferOverrun = MAKE_STATUS(kStatusGroup_UART, 8),
kStatus_UART_RxHardwareOverrun = MAKE_STATUS(kStatusGroup_UART, 9),
kStatus_UART_NoiseError = MAKE_STATUS(kStatusGroup_UART, 10),
kStatus_UART_FramingError = MAKE_STATUS(kStatusGroup_UART, 11),
kStatus_UART_ParityError = MAKE_STATUS(kStatusGroup_UART, 12)
} |
| Error codes for the UART driver. More...
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enum | uart_parity_mode_t {
kUART_ParityDisabled = 0x0U,
kUART_ParityEven = 0x2U,
kUART_ParityOdd = 0x3U
} |
| UART parity mode. More...
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enum | uart_stop_bit_count_t {
kUART_OneStopBit = 0U,
kUART_TwoStopBit = 1U
} |
| UART stop bit count. More...
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enum | _uart_interrupt_enable {
kUART_RxActiveEdgeInterruptEnable = (UART_BDH_RXEDGIE_MASK),
kUART_TxDataRegEmptyInterruptEnable = (UART_C2_TIE_MASK << 8),
kUART_TransmissionCompleteInterruptEnable = (UART_C2_TCIE_MASK << 8),
kUART_RxDataRegFullInterruptEnable = (UART_C2_RIE_MASK << 8),
kUART_IdleLineInterruptEnable = (UART_C2_ILIE_MASK << 8),
kUART_RxOverrunInterruptEnable = (UART_C3_ORIE_MASK << 16),
kUART_NoiseErrorInterruptEnable = (UART_C3_NEIE_MASK << 16),
kUART_FramingErrorInterruptEnable = (UART_C3_FEIE_MASK << 16),
kUART_ParityErrorInterruptEnable = (UART_C3_PEIE_MASK << 16)
} |
| UART interrupt configuration structure, default settings all disabled. More...
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enum | _uart_flags {
kUART_TxDataRegEmptyFlag = (UART_S1_TDRE_MASK),
kUART_TransmissionCompleteFlag = (UART_S1_TC_MASK),
kUART_RxDataRegFullFlag = (UART_S1_RDRF_MASK),
kUART_IdleLineFlag = (UART_S1_IDLE_MASK),
kUART_RxOverrunFlag = (UART_S1_OR_MASK),
kUART_NoiseErrorFlag = (UART_S1_NF_MASK),
kUART_FramingErrorFlag = (UART_S1_FE_MASK),
kUART_ParityErrorFlag = (UART_S1_PF_MASK),
kUART_RxActiveEdgeFlag = (UART_S2_RXEDGIF_MASK << 8),
kUART_RxActiveFlag = (UART_S2_RAF_MASK << 8)
} |
| UART status flags. More...
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static void | UART_EnableTx (UART_Type *base, bool enable) |
| Enables or disables the UART transmitter. More...
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static void | UART_EnableRx (UART_Type *base, bool enable) |
| Enables or disables the UART receiver. More...
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static void | UART_WriteByte (UART_Type *base, uint8_t data) |
| Writes to the TX register. More...
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static uint8_t | UART_ReadByte (UART_Type *base) |
| Reads the RX register directly. More...
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void | UART_WriteBlocking (UART_Type *base, const uint8_t *data, size_t length) |
| Writes to the TX register using a blocking method. More...
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status_t | UART_ReadBlocking (UART_Type *base, uint8_t *data, size_t length) |
| Read RX data register using a blocking method. More...
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void | UART_TransferCreateHandle (UART_Type *base, uart_handle_t *handle, uart_transfer_callback_t callback, void *userData) |
| Initializes the UART handle. More...
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void | UART_TransferStartRingBuffer (UART_Type *base, uart_handle_t *handle, uint8_t *ringBuffer, size_t ringBufferSize) |
| Sets up the RX ring buffer. More...
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void | UART_TransferStopRingBuffer (UART_Type *base, uart_handle_t *handle) |
| Aborts the background transfer and uninstalls the ring buffer. More...
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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...
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void | UART_TransferAbortSend (UART_Type *base, uart_handle_t *handle) |
| Aborts the interrupt driven data transmit. More...
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status_t | UART_TransferGetSendCount (UART_Type *base, uart_handle_t *handle, uint32_t *count) |
| Get the number of bytes that have been written to UART TX register. More...
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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...
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void | UART_TransferAbortReceive (UART_Type *base, uart_handle_t *handle) |
| Aborts the interrupt-driven data receiving. More...
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status_t | UART_TransferGetReceiveCount (UART_Type *base, uart_handle_t *handle, uint32_t *count) |
| Get the number of bytes that have been received. More...
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void | UART_TransferHandleIRQ (UART_Type *base, uart_handle_t *handle) |
| UART IRQ handle function. More...
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void | UART_TransferHandleErrorIRQ (UART_Type *base, uart_handle_t *handle) |
| UART Error IRQ handle function. More...
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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 |
void* uart_handle_t::userData |
volatile uint8_t uart_handle_t::txState |
typedef void(* uart_transfer_callback_t)(UART_Type *base, uart_handle_t *handle, status_t status, void *userData) |
Enumerator |
---|
kStatus_UART_TxBusy |
Transmitter is busy.
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kStatus_UART_RxBusy |
Receiver is busy.
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kStatus_UART_TxIdle |
UART transmitter is idle.
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kStatus_UART_RxIdle |
UART receiver is idle.
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kStatus_UART_TxWatermarkTooLarge |
TX FIFO watermark too large.
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kStatus_UART_RxWatermarkTooLarge |
RX FIFO watermark too large.
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kStatus_UART_FlagCannotClearManually |
UART flag can't be manually cleared.
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kStatus_UART_Error |
Error happens on UART.
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kStatus_UART_RxRingBufferOverrun |
UART RX software ring buffer overrun.
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kStatus_UART_RxHardwareOverrun |
UART RX receiver overrun.
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kStatus_UART_NoiseError |
UART noise error.
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kStatus_UART_FramingError |
UART framing error.
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kStatus_UART_ParityError |
UART parity error.
|
Enumerator |
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kUART_ParityDisabled |
Parity disabled.
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kUART_ParityEven |
Parity enabled, type even, bit setting: PE|PT = 10.
|
kUART_ParityOdd |
Parity enabled, type odd, bit setting: PE|PT = 11.
|
Enumerator |
---|
kUART_OneStopBit |
One stop bit.
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kUART_TwoStopBit |
Two stop bits.
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This structure contains the settings for all of the UART interrupt configurations.
Enumerator |
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kUART_RxActiveEdgeInterruptEnable |
RX active edge interrupt.
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kUART_TxDataRegEmptyInterruptEnable |
Transmit data register empty interrupt.
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kUART_TransmissionCompleteInterruptEnable |
Transmission complete interrupt.
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kUART_RxDataRegFullInterruptEnable |
Receiver data register full interrupt.
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kUART_IdleLineInterruptEnable |
Idle line interrupt.
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kUART_RxOverrunInterruptEnable |
Receiver overrun interrupt.
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kUART_NoiseErrorInterruptEnable |
Noise error flag interrupt.
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kUART_FramingErrorInterruptEnable |
Framing error flag interrupt.
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kUART_ParityErrorInterruptEnable |
Parity error flag interrupt.
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This provides constants for the UART status flags for use in the UART functions.
Enumerator |
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kUART_TxDataRegEmptyFlag |
TX data register empty flag.
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kUART_TransmissionCompleteFlag |
Transmission complete flag.
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kUART_RxDataRegFullFlag |
RX data register full flag.
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kUART_IdleLineFlag |
Idle line detect flag.
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kUART_RxOverrunFlag |
RX overrun flag.
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kUART_NoiseErrorFlag |
RX takes 3 samples of each received bit.
If any of these samples differ, noise flag sets
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kUART_FramingErrorFlag |
Frame error flag, sets if logic 0 was detected where stop bit expected.
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kUART_ParityErrorFlag |
If parity enabled, sets upon parity error detection.
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kUART_RxActiveEdgeFlag |
RX pin active edge interrupt flag, sets when active edge detected.
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kUART_RxActiveFlag |
Receiver Active Flag (RAF), sets at beginning of valid start bit.
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void UART_Init |
( |
UART_Type * |
base, |
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const uart_config_t * |
config, |
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uint32_t |
srcClock_Hz |
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) |
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This function configures the UART module with the user-defined settings. The user can configure the configuration structure and also get the default configuration by using the UART_GetDefaultConfig() function. Example below shows how to use this API to configure UART.
uartConfig.txFifoWatermark = 0;
uartConfig.rxFifoWatermark = 1;
- Parameters
-
base | UART peripheral base address. |
config | Pointer to user-defined configuration structure. |
srcClock_Hz | UART clock source frequency in HZ. |
void UART_Deinit |
( |
UART_Type * |
base | ) |
|
This function waits for TX complete, disables TX and RX, and disables the UART clock.
- Parameters
-
base | UART peripheral base address. |
This function initializes the UART configuration structure to a default value. The default values are: uartConfig->baudRate_Bps = 115200U; uartConfig->bitCountPerChar = kUART_8BitsPerChar; uartConfig->parityMode = kUART_ParityDisabled; uartConfig->stopBitCount = kUART_OneStopBit; uartConfig->txFifoWatermark = 0; uartConfig->rxFifoWatermark = 1; uartConfig->enableTx = false; uartConfig->enableRx = false;
- Parameters
-
config | Pointer to configuration structure. |
void UART_SetBaudRate |
( |
UART_Type * |
base, |
|
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uint32_t |
baudRate_Bps, |
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uint32_t |
srcClock_Hz |
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) |
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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.
- Parameters
-
base | UART peripheral base address. |
baudRate_Bps | UART baudrate to be set. |
srcClock_Hz | UART clock source freqency in HZ. |
uint32_t UART_GetStatusFlags |
( |
UART_Type * |
base | ) |
|
This function get all UART status flags, the flags are returned as the logical OR value of the enumerators _uart_flags. To check specific status, compare the return value with enumerators in _uart_flags. For example, to check whether the TX is empty:
- Parameters
-
base | UART peripheral base address. |
- Returns
- UART status flags which are ORed by the enumerators in the _uart_flags.
status_t UART_ClearStatusFlags |
( |
UART_Type * |
base, |
|
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uint32_t |
mask |
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) |
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This function clears UART status flags with a provided mask. Automatically cleared flag can't be cleared by this function. Some flags can only be cleared or set by hardware itself. These flags are: kUART_TxDataRegEmptyFlag, kUART_TransmissionCompleteFlag, kUART_RxDataRegFullFlag, kUART_RxActiveFlag, kUART_NoiseErrorInRxDataRegFlag, kUART_ParityErrorInRxDataRegFlag, kUART_TxFifoEmptyFlag,kUART_RxFifoEmptyFlag Note: This API should be called when the Tx/Rx is idle, otherwise it takes no effects.
- Parameters
-
base | UART peripheral base address. |
mask | The status flags to be cleared, it is logical OR value of _uart_flags. |
- Return values
-
kStatus_UART_FlagCannotClearManually | The flag can't be cleared by this function but it is cleared automatically by hardware. |
kStatus_Success | Status in the mask are cleared. |
void UART_EnableInterrupts |
( |
UART_Type * |
base, |
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uint32_t |
mask |
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) |
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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 full interrupt:
- Parameters
-
void UART_DisableInterrupts |
( |
UART_Type * |
base, |
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uint32_t |
mask |
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) |
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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 full interrupt:
- Parameters
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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 specific interrupts enable status, compare the return value with enumerators in _uart_interrupt_enable. For example, to check whether TX empty interrupt is enabled:
- 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 |
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) |
| |
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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, |
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|
bool |
enable |
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) |
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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, |
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uint8_t |
data |
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) |
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inlinestatic |
This function writes data to the TX register directly. The upper layer must ensure that the TX register is empty or TX FIFO has empty room before calling this function.
- Parameters
-
base | UART peripheral base address. |
data | The byte to write. |
static uint8_t UART_ReadByte |
( |
UART_Type * |
base | ) |
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inlinestatic |
This function reads data from the TX register directly. The upper layer must ensure that the RX register is full or that the TX FIFO has data before calling this function.
- Parameters
-
base | UART peripheral base address. |
- Returns
- The byte read from UART data register.
void UART_WriteBlocking |
( |
UART_Type * |
base, |
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const uint8_t * |
data, |
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size_t |
length |
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) |
| |
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.
- Note
- This function does not check whether all the data has been sent out to the bus. Before disabling the TX, check kUART_TransmissionCompleteFlag to ensure that the TX is finished.
- 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, |
|
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uint8_t * |
data, |
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size_t |
length |
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) |
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This function polls the RX register, waits for the RX register to be full or for RX FIFO to have data and read 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 happened while receiving data. |
kStatus_UART_NoiseError | Noise error happened while receiving data. |
kStatus_UART_FramingError | Framing error happened while receiving data. |
kStatus_UART_ParityError | Parity error happened while receiving data. |
kStatus_Success | Successfully received all data. |
void UART_TransferCreateHandle |
( |
UART_Type * |
base, |
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uart_handle_t * |
handle, |
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uart_transfer_callback_t |
callback, |
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void * |
userData |
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) |
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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, |
|
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uart_handle_t * |
handle, |
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uint8_t * |
ringBuffer, |
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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 there is already data 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, then 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. |
status_t UART_TransferSendNonBlocking |
( |
UART_Type * |
base, |
|
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uart_handle_t * |
handle, |
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uart_transfer_t * |
xfer |
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) |
| |
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 are 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 still 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 that have been written to UART TX register by 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 | 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 |
|
) |
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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, refer to 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 |
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) |
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This function aborts the interrupt-driven data receiving. The user can get the remainBytes to know how many bytes 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. |
void UART_TransferHandleErrorIRQ |
( |
UART_Type * |
base, |
|
|
uart_handle_t * |
handle |
|
) |
| |
This function handle the UART error IRQ request.
- Parameters
-
base | UART peripheral base address. |
handle | UART handle pointer. |