USART - Synchronous/Asynchronous Serial#

USART_Databits_TypeDef#

USART_Databits_TypeDef

Databit selection.

USART_Enable_TypeDef#

USART_Enable_TypeDef

Enable selection.

USART_OVS_TypeDef#

USART_OVS_TypeDef

Oversampling selection, used for asynchronous operation.

USART_Parity_TypeDef#

USART_Parity_TypeDef

Parity selection, mainly used for asynchronous operation.

USART_Stopbits_TypeDef#

USART_Stopbits_TypeDef

Stop bits selection, used for asynchronous operation.

USART_ClockMode_TypeDef#

USART_ClockMode_TypeDef

Clock polarity/phase mode.

USART_IrDAPw_Typedef#

USART_IrDAPw_Typedef

Pulse width selection for IrDA mode.

USART_PRS_Channel_t#

typedef uint8_t USART_PRS_Channel_t

PRS Channel type.

USART_BaudrateAsyncSet#

void USART_BaudrateAsyncSet (USART_TypeDef * usart, uint32_t refFreq, uint32_t baudrate, USART_OVS_TypeDef ovs)

Configure USART/UART operating in asynchronous mode to use a given baudrate (or as close as possible to a specified baudrate).

USART_BaudrateCalc#

uint32_t USART_BaudrateCalc (uint32_t refFreq, uint32_t clkdiv, bool syncmode, USART_OVS_TypeDef ovs)

Calculate baudrate for USART/UART given reference frequency, clock division, and oversampling rate (if async mode).

This function returns the baudrate that a USART/UART module will use if configured with the given frequency, clock divisor, and mode. Notice that this function will not use the hardware configuration. It can be used to determine if a given configuration is sufficiently accurate for the application.

Returns

• Baudrate with given settings.

USART_BaudrateGet#

uint32_t USART_BaudrateGet (USART_TypeDef * usart)

Get the current baudrate for USART/UART.

This function returns the actual baudrate (not considering oscillator inaccuracies) used by a USART/UART peripheral.

Returns

• The current baudrate.

USART_BaudrateSyncSet#

void USART_BaudrateSyncSet (USART_TypeDef * usart, uint32_t refFreq, uint32_t baudrate)

Configure the USART operating in synchronous mode to use a given baudrate (or as close as possible to a specified baudrate).

The configuration will be set to use a baudrate <= the specified baudrate to ensure that the baudrate does not exceed the specified value.

The fractional clock division is suppressed, although the hardware design allows it. It could cause half clock cycles to exceed a specified limit and thus potentially violate specifications for the slave device. In some special situations, a fractional clock division may be useful even in synchronous mode, but in those cases it must be directly adjusted, possibly assisted by USART_BaudrateCalc():

Warnings

• The consequence of the aforementioned suppression of the fractional part of the clock divider is that some frequencies won't be achievable. The divider will only be able to be an integer value so the reference clock will only be dividable by N (where N is a positive integer).

USART_Enable#

void USART_Enable (USART_TypeDef * usart, USART_Enable_TypeDef enable)

Enable/disable USART/UART receiver and/or transmitter.

Notice that this function does not do any configuration. Enabling should normally be done after initialization (if not enabled as part of initialization).

USART_InitAsync#

void USART_InitAsync (USART_TypeDef * usart, const USART_InitAsync_TypeDef * init)

Initialize USART/UART for normal asynchronous mode.

This function will configure basic settings to operate in normal asynchronous mode.

A special control setup not covered by this function must be done after using this function by direct modification of the CTRL register.

Notice that pins used by the USART/UART module must be properly configured by the user explicitly for the USART/UART to work as intended. (When configuring pins, remember to consider the sequence of configuration to avoid unintended pulses/glitches on output pins.)

USART_InitSync#

void USART_InitSync (USART_TypeDef * usart, const USART_InitSync_TypeDef * init)

Initialize USART for synchronous mode.

This function will configure basic settings to operate in synchronous mode.

A special control setup not covered by this function must be done after using this function by direct modification of the CTRL register.

Notice that pins used by the USART module must be properly configured by the user explicitly for the USART to work as intended. (When configuring pins remember to consider the sequence of configuration to avoid unintended pulses/glitches on output pins.)

USARTn_InitIrDA#

void USARTn_InitIrDA (USART_TypeDef * usart, const USART_InitIrDA_TypeDef * init)

Initialize USART for asynchronous IrDA mode.

This function will configure basic settings to operate in asynchronous IrDA mode.

A special control setup not covered by this function must be done after using this function by direct modification of the CTRL and IRCTRL registers.

Notice that pins used by the USART/UART module must be properly configured by the user explicitly for the USART/UART to work as intended. (When configuring pins, remember to consider the sequence of configuration to avoid unintended pulses/glitches on output pins.)

Note

• Not all USART instances support IrDA. See the data sheet for your device.

USART_InitPrsTrigger#

void USART_InitPrsTrigger (USART_TypeDef * usart, const USART_PrsTriggerInit_TypeDef * init)

Initialize the automatic transmissions using PRS channel as a trigger.

Note

• Initialize USART with USART_Init() before setting up the PRS configuration.

USART_IntClear#

void USART_IntClear (USART_TypeDef * usart, uint32_t flags)

Clear one or more pending USART interrupts.

USART_IntDisable#

void USART_IntDisable (USART_TypeDef * usart, uint32_t flags)

Disable one or more USART interrupts.

USART_IntEnable#

void USART_IntEnable (USART_TypeDef * usart, uint32_t flags)

Enable one or more USART interrupts.

Note

• Depending on the use, a pending interrupt may already be set prior to enabling the interrupt. To ignore a pending interrupt, consider using USART_IntClear() prior to enabling the interrupt.

USART_IntGet#

uint32_t USART_IntGet (USART_TypeDef * usart)

Get pending USART interrupt flags.

Note

• The event bits are not cleared by the use of this function.

Returns

• USART/UART interrupt source(s) pending. Returns one or more valid interrupt flags for the USART module (USART_IF_nnn) OR'ed together.

USART_IntGetEnabled#

uint32_t USART_IntGetEnabled (USART_TypeDef * usart)

Get enabled and pending USART interrupt flags.

Useful for handling more interrupt sources in the same interrupt handler.

Note

• Interrupt flags are not cleared by the use of this function.

Returns

• Pending and enabled USART interrupt sources. The return value is the bitwise AND combination of

  • the OR combination of enabled interrupt sources in USARTx_IEN_nnn register (USARTx_IEN_nnn) and

  • the OR combination of valid interrupt flags of the USART module (USARTx_IF_nnn).

USART_IntSet#

void USART_IntSet (USART_TypeDef * usart, uint32_t flags)

Set one or more pending USART interrupts from SW.

USART_StatusGet#

uint32_t USART_StatusGet (USART_TypeDef * usart)

Get USART STATUS register.

Returns

• STATUS register value.

USART_Reset#

void USART_Reset (USART_TypeDef * usart)

Reset USART/UART to the same state that it was in after a hardware reset.

USART_Rx#

uint8_t USART_Rx (USART_TypeDef * usart)

Receive one 4-8 bit frame, (or part of 10-16 bit frame).

This function is normally used to receive one frame when operating with frame length 4-8 bits. See USART_RxExt() for reception of 9 bit frames.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is empty until data is received. Alternatively, the user can explicitly check whether data is available. If data is available, call USART_RxDataGet() to read the RXDATA register directly.

Returns

• Data received.

USART_RxDouble#

uint16_t USART_RxDouble (USART_TypeDef * usart)

Receive two 4-8 bit frames or one 10-16 bit frame.

This function is normally used to receive one frame when operating with frame length 10-16 bits. See USART_RxDoubleExt() for reception of two 9 bit frames.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is empty until data is received. Alternatively, the user can explicitly check whether data is available. If data is available, call USART_RxDoubleGet() to read the RXDOUBLE register directly.

Returns

• Data received.

USART_RxDoubleExt#

uint32_t USART_RxDoubleExt (USART_TypeDef * usart)

Receive two 4-9 bit frames, or one 10-16 bit frame with extended information.

This function is normally used to receive one frame when operating with frame length 10-16 bits and additional RX status information is required.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if buffer is empty until data is received. Alternatively, the user can explicitly check whether data is available. If data is available, call USART_RxDoubleXGet() to read the RXDOUBLEX register directly.

Returns

• Data received.

USART_RxExt#

uint16_t USART_RxExt (USART_TypeDef * usart)

Receive one 4-9 bit frame (or part of 10-16 bit frame) with extended information.

This function is normally used to receive one frame when operating with frame length 4-9 bits and additional RX status information is required.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is empty until data is received. Alternatively, the user can explicitly check whether data is available. If data is available, call USART_RxDataXGet() to read the RXDATAX register directly.

Returns

• Data received.

USART_RxDataGet#

uint8_t USART_RxDataGet (USART_TypeDef * usart)

Receive one 4-8 bit frame, (or part of 10-16 bit frame).

This function is used to quickly receive one 4-8 bits frame by reading the RXDATA register directly, without checking the STATUS register for the RXDATAV flag. This can be useful from the RXDATAV interrupt handler, i.e., waiting is superfluous, in order to quickly read the received data. Please refer to USART_RxDataXGet() for reception of 9 bit frames.

Note

• Because this function does not check whether the RXDATA register actually holds valid data, it should only be used in situations when it is certain that there is valid data, ensured by some external program routine, e.g., when handling an RXDATAV interrupt. The USART_Rx() is normally a better choice if the validity of the RXDATA register is not certain.

• Notice that possible parity/stop bits in asynchronous mode are not considered part of specified frame bit length.

Returns

• Data received.

USART_RxDoubleGet#

uint16_t USART_RxDoubleGet (USART_TypeDef * usart)

Receive two 4-8 bit frames, or one 10-16 bit frame.

This function is used to quickly receive one 10-16 bits frame or two 4-8 bit frames by reading the RXDOUBLE register directly, without checking the STATUS register for the RXDATAV flag. This can be useful from the RXDATAV interrupt handler, i.e., waiting is superfluous, in order to quickly read the received data. This function is normally used to receive one frame when operating with frame length 10-16 bits. Please refer to USART_RxDoubleXGet() for reception of two 9 bit frames.

Note

• Because this function does not check whether the RXDOUBLE register actually holds valid data, it should only be used in situations when it is certain that there is valid data, ensured by some external program routine, e.g., when handling an RXDATAV interrupt. The USART_RxDouble() is normally a better choice if the validity of the RXDOUBLE register is not certain.

• Notice that possible parity/stop bits in asynchronous mode are not considered part of specified frame bit length.

Returns

• Data received.

USART_RxDoubleXGet#

uint32_t USART_RxDoubleXGet (USART_TypeDef * usart)

Receive two 4-9 bit frames, or one 10-16 bit frame with extended information.

This function is used to quickly receive one 10-16 bits frame or two 4-9 bit frames by reading the RXDOUBLEX register directly, without checking the STATUS register for the RXDATAV flag. This can be useful from the RXDATAV interrupt handler, i.e., waiting is superfluous, in order to quickly read the received data.

Note

• Because this function does not check whether the RXDOUBLEX register actually holds valid data, it should only be used in situations when it is certain that there is valid data, ensured by some external program routine, e.g., when handling an RXDATAV interrupt. The USART_RxDoubleExt() is normally a better choice if the validity of the RXDOUBLEX register is not certain.

• Notice that possible parity/stop bits in asynchronous mode are not considered part of specified frame bit length.

Returns

• Data received.

USART_RxDataXGet#

uint16_t USART_RxDataXGet (USART_TypeDef * usart)

Receive one 4-9 bit frame, (or part of 10-16 bit frame) with extended information.

This function is used to quickly receive one 4-9 bit frame, (or part of 10-16 bit frame) with extended information by reading the RXDATAX register directly, without checking the STATUS register for the RXDATAV flag. This can be useful from the RXDATAV interrupt handler, i.e., waiting is superfluous, in order to quickly read the received data.

Note

• Because this function does not check whether the RXDATAX register actually holds valid data, it should only be used in situations when it is certain that there is valid data, ensured by some external program routine, e.g., when handling an RXDATAV interrupt. The USART_RxExt() is normally a better choice if the validity of the RXDATAX register is not certain.

• Notice that possible parity/stop bits in asynchronous mode are not considered part of specified frame bit length.

Returns

• Data received.

USART_SpiTransfer#

uint8_t USART_SpiTransfer (USART_TypeDef * usart, uint8_t data)

Perform one 8 bit frame SPI transfer.

Note

• This function will stall if the transmit buffer is full. When a transmit buffer becomes available, data is written and the function will wait until data is fully transmitted. The SPI return value is then read out and returned.

Returns

• Data received.

USART_Tx#

void USART_Tx (USART_TypeDef * usart, uint8_t data)

Transmit one 4-9 bit frame.

Depending on the frame length configuration, 4-8 (least significant) bits from data are transmitted. If the frame length is 9, 8 bits are transmitted from data and one bit as specified by CTRL register, BIT8DV field. See USART_TxExt() for transmitting 9 bit frame with full control of all 9 bits.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is full until the buffer becomes available.

USART_TxDouble#

void USART_TxDouble (USART_TypeDef * usart, uint16_t data)

Transmit two 4-9 bit frames or one 10-16 bit frame.

Depending on the frame length configuration, 4-8 (least significant) bits from each byte in data are transmitted. If frame length is 9, 8 bits are transmitted from each byte in data adding one bit as specified by the CTRL register, BIT8DV field, to each byte. See USART_TxDoubleExt() for transmitting two 9 bit frames with full control of all 9 bits.

If the frame length is 10-16, 10-16 (least significant) bits from data are transmitted.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is full until the buffer becomes available.

USART_TxDoubleExt#

void USART_TxDoubleExt (USART_TypeDef * usart, uint32_t data)

Transmit two 4-9 bit frames or one 10-16 bit frame with extended control.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is full until the buffer becomes available.

• If the frame length is 10-16 bits, 8 data bits are taken from the least significant 16 bit word and the remaining bits from the other 16 bit word.

• Additional control bits are available as documented in the reference manual (set to 0 if not used). For 10-16 bit frame length, these control bits are taken from the most significant 16 bit word.

USART_TxExt#

void USART_TxExt (USART_TypeDef * usart, uint16_t data)

Transmit one 4-9 bit frame with extended control.

Notice that possible parity/stop bits in asynchronous mode are not considered part of a specified frame bit length.

Note

• This function will stall if the buffer is full until the buffer becomes available.

USART_INITASYNC_DEFAULT#

#define USART_INITASYNC_DEFAULT

Default configuration for USART asynchronous initialization structure.

USART_INITPRSTRIGGER_DEFAULT#

#define USART_INITPRSTRIGGER_DEFAULT

Default configuration for USART PRS triggering structure.

USART_INITSYNC_DEFAULT#

#define USART_INITSYNC_DEFAULT

Default configuration for USART sync initialization structure.

USART_INITIRDA_DEFAULT#

#define USART_INITIRDA_DEFAULT

Default configuration for IrDA mode initialization structure.