LEUART - Low Energy UART
Description
Low Energy Universal Asynchronous Receiver/Transmitter (LEUART) Peripheral API.
This module contains functions to control the LEUART peripheral of Silicon Labs 32-bit MCUs and SoCs. The LEUART module provides the full UART communication using a low frequency 32.768 kHz clock and has special features for communication without the CPU intervention.
Data Structures |
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struct | LEUART_Init_TypeDef |
Initialization structure.
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Functions |
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uint32_t | LEUART_BaudrateCalc (uint32_t refFreq, uint32_t clkdiv) |
Calculate the baudrate for the LEUART given reference frequency and clock division.
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uint32_t | LEUART_BaudrateGet (LEUART_TypeDef *leuart) |
Get the current baudrate for LEUART.
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void | LEUART_BaudrateSet (LEUART_TypeDef *leuart, uint32_t refFreq, uint32_t baudrate) |
Configure the baudrate (or as close as possible to a specified baudrate).
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void | LEUART_Enable (LEUART_TypeDef *leuart, LEUART_Enable_TypeDef enable) |
Enable/disable the LEUART receiver and/or transmitter.
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void | LEUART_FreezeEnable (LEUART_TypeDef *leuart, bool enable) |
LEUART register synchronization freeze control.
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void | LEUART_Init (LEUART_TypeDef *leuart, LEUART_Init_TypeDef const *init) |
Initialize LEUART.
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void | LEUART_Reset (LEUART_TypeDef *leuart) |
Reset LEUART to the same state that it was in after a hardware reset.
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uint8_t | LEUART_Rx (LEUART_TypeDef *leuart) |
Receive one 8 bit frame, (or part of 9 bit frame).
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uint16_t | LEUART_RxExt (LEUART_TypeDef *leuart) |
Receive one 8-9 bit frame with extended information.
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void | LEUART_Tx (LEUART_TypeDef *leuart, uint8_t data) |
Transmit one frame.
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void | LEUART_TxExt (LEUART_TypeDef *leuart, uint16_t data) |
Transmit one 8-9 bit frame with extended control.
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void | LEUART_TxDmaInEM2Enable (LEUART_TypeDef *leuart, bool enable) |
Enables handling of LEUART TX by DMA in EM2.
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void | LEUART_RxDmaInEM2Enable (LEUART_TypeDef *leuart, bool enable) |
Enables handling of LEUART RX by DMA in EM2.
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void | LEUART_IntClear (LEUART_TypeDef *leuart, uint32_t flags) |
Clear one or more pending LEUART interrupts.
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void | LEUART_IntDisable (LEUART_TypeDef *leuart, uint32_t flags) |
Disable one or more LEUART interrupts.
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void | LEUART_IntEnable (LEUART_TypeDef *leuart, uint32_t flags) |
Enable one or more LEUART interrupts.
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uint32_t | LEUART_IntGet (LEUART_TypeDef *leuart) |
Get pending LEUART interrupt flags.
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uint32_t | LEUART_IntGetEnabled (LEUART_TypeDef *leuart) |
Get enabled and pending LEUART interrupt flags.
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void | LEUART_IntSet (LEUART_TypeDef *leuart, uint32_t flags) |
Set one or more pending LEUART interrupts from SW.
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uint32_t | LEUART_StatusGet (LEUART_TypeDef *leuart) |
Get LEUART STATUS register.
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uint8_t | LEUART_RxDataGet (LEUART_TypeDef *leuart) |
Receive one 8 bit frame, (or part of a 9 bit frame).
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uint16_t | LEUART_RxDataXGet (LEUART_TypeDef *leuart) |
Receive one 8-9 bit frame, with extended information.
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Macros |
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#define | LEUART_INIT_DEFAULT |
Default configuration for LEUART initialization structure.
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Enumerations |
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enum |
LEUART_Databits_TypeDef
{
leuartDatabits8 = LEUART_CTRL_DATABITS_EIGHT, leuartDatabits9 = LEUART_CTRL_DATABITS_NINE } |
Data bit selection.
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enum |
LEUART_Enable_TypeDef
{
leuartDisable = 0x0, leuartEnableRx = LEUART_CMD_RXEN, leuartEnableTx = LEUART_CMD_TXEN, leuartEnable = (LEUART_CMD_RXEN | LEUART_CMD_TXEN) } |
Enable selection.
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enum |
LEUART_Parity_TypeDef
{
leuartNoParity = LEUART_CTRL_PARITY_NONE, leuartEvenParity = LEUART_CTRL_PARITY_EVEN, leuartOddParity = LEUART_CTRL_PARITY_ODD } |
Parity selection.
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enum |
LEUART_Stopbits_TypeDef
{
leuartStopbits1 = LEUART_CTRL_STOPBITS_ONE, leuartStopbits2 = LEUART_CTRL_STOPBITS_TWO } |
Stop bits selection.
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Function Documentation
◆ LEUART_BaudrateCalc()
uint32_t LEUART_BaudrateCalc | ( | uint32_t |
refFreq,
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uint32_t |
clkdiv
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Calculate the baudrate for the LEUART given reference frequency and clock division.
This function returns the baudrate that a LEUART module will use if configured with the given frequency and clock divisor. 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.
- Parameters
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[in] refFreq
The LEUART peripheral frequency used. [in] clkdiv
The clock division factor to be used.
- Returns
- A baudrate with given settings.
◆ LEUART_BaudrateGet()
uint32_t LEUART_BaudrateGet | ( | LEUART_TypeDef * |
leuart
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) |
Get the current baudrate for LEUART.
This function returns the actual baudrate (not considering the oscillator inaccuracies) used by the LEUART peripheral.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block.
- Returns
- The current baudrate.
◆ LEUART_BaudrateSet()
void LEUART_BaudrateSet | ( | LEUART_TypeDef * |
leuart,
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uint32_t |
refFreq,
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uint32_t |
baudrate
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Configure the baudrate (or as close as possible to a specified baudrate).
- Note
- The baudrate setting requires synchronization into the low-frequency domain. If the same register is modified before a previous update has completed, this function will stall until the previous synchronization has completed.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] refFreq
The LEUART reference clock frequency in Hz that will be used. If set to 0, the currently configured reference clock is assumed. [in] baudrate
A baudrate to try to achieve for LEUART.
◆ LEUART_Enable()
void LEUART_Enable | ( | LEUART_TypeDef * |
leuart,
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LEUART_Enable_TypeDef |
enable
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Enable/disable the LEUART receiver and/or transmitter.
Notice that this function does not do any configuration. Enabling should normally be done after the initialization is done (if not enabled as part of initialization).
- Note
- Enabling/disabling requires synchronization into the low-frequency domain. If the same register is modified before a previous update has completed, this function will stall until the previous synchronization has completed.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] enable
Select status for receiver/transmitter.
◆ LEUART_FreezeEnable()
void LEUART_FreezeEnable | ( | LEUART_TypeDef * |
leuart,
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bool |
enable
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) |
LEUART register synchronization freeze control.
Some LEUART registers require synchronization into the low-frequency (LF) domain. The freeze feature allows for several such registers to be modified before passing them to the LF domain simultaneously (which takes place when the freeze mode is disabled).
- Note
- When enabling freeze mode, this function will wait for all current ongoing LEUART synchronization to the LF domain to complete (Normally synchronization will not be in progress.) However, for this reason, when using freeze mode, modifications of registers requiring LF synchronization should be done within one freeze enable/disable block to avoid unnecessary stalling.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] enable
- True - enable freeze, modified registers are not propagated to the LF domain
- False - disables freeze, modified registers are propagated to the LF domain
◆ LEUART_Init()
void LEUART_Init | ( | LEUART_TypeDef * |
leuart,
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LEUART_Init_TypeDef const * |
init
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) |
Initialize LEUART.
This function will configure basic settings to operate in normal asynchronous mode. Consider using
LEUART_Reset()
prior to this function if the state of configuration is not known, since only configuration settings specified by
init
are set.
Special control setup not covered by this function may be done either before or after using this function (but normally before enabling) by direct modification of the CTRL register.
Notice that pins used by the LEUART module must be properly configured by the user explicitly for the LEUART to work as intended. (When configuring pins consider the sequence of configuration to avoid unintended pulses/glitches on output pins.)
- Note
- Initializing requires synchronization into the low-frequency domain. If the same register is modified before a previous update has completed, this function will stall until the previous synchronization has completed.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] init
A pointer to the initialization structure used to configure basic async setup.
◆ LEUART_Reset()
void LEUART_Reset | ( | LEUART_TypeDef * |
leuart
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) |
Reset LEUART to the same state that it was in after a hardware reset.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block.
◆ LEUART_Rx()
uint8_t LEUART_Rx | ( | LEUART_TypeDef * |
leuart
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) |
Receive one 8 bit frame, (or part of 9 bit frame).
This function is normally used to receive one frame when operating with frame length 8 bits. See LEUART_RxExt() for reception of 9 bit frames.
Notice that possible parity/stop bits are not considered a part of the specified frame bit length.
- Note
- This function will stall if the buffer is empty until data is received.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block.
- Returns
- Data received.
◆ LEUART_RxExt()
uint16_t LEUART_RxExt | ( | LEUART_TypeDef * |
leuart
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) |
Receive one 8-9 bit frame with extended information.
This function is normally used to receive one frame and additional RX status information is required.
- Note
- This function will stall if buffer is empty until data is received.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block.
- Returns
- Data received.
◆ LEUART_Tx()
void LEUART_Tx | ( | LEUART_TypeDef * |
leuart,
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uint8_t |
data
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) |
Transmit one frame.
Depending on the frame length configuration, 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 the CTRL register, BIT8DV field. See
LEUART_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 a part of the specified frame bit length.
- Note
- This function will stall if buffer is full until the buffer becomes available.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] data
Data to transmit. See details above for more info.
◆ LEUART_TxExt()
void LEUART_TxExt | ( | LEUART_TypeDef * |
leuart,
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uint16_t |
data
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Transmit one 8-9 bit frame with extended control.
Notice that possible parity/stop bits in asynchronous mode are not considered a part of the specified frame bit length.
- Note
- This function will stall if the buffer is full until the buffer becomes available.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] data
Data to transmit with extended control. Least significant bit contains frame bits and additional control bits are available as documented in the reference manual (set to 0 if not used).
◆ LEUART_TxDmaInEM2Enable()
void LEUART_TxDmaInEM2Enable | ( | LEUART_TypeDef * |
leuart,
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bool |
enable
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) |
Enables handling of LEUART TX by DMA in EM2.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] enable
True - enables functionality False - disables functionality
◆ LEUART_RxDmaInEM2Enable()
void LEUART_RxDmaInEM2Enable | ( | LEUART_TypeDef * |
leuart,
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bool |
enable
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Enables handling of LEUART RX by DMA in EM2.
- Parameters
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[in] leuart
A pointer to the LEUART peripheral register block. [in] enable
True - enables functionality False - disables functionality
◆ LEUART_IntClear()
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inline |
Clear one or more pending LEUART interrupts.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block. [in] flags
Pending LEUART interrupt source to clear. Use a bitwise logic OR combination of valid interrupt flags for LEUART module (LEUART_IF_nnn).
◆ LEUART_IntDisable()
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inline |
Disable one or more LEUART interrupts.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block. [in] flags
LEUART interrupt sources to disable. Use a bitwise logic OR combination of valid interrupt flags for LEUART module (LEUART_IF_nnn).
◆ LEUART_IntEnable()
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inline |
Enable one or more LEUART 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 LEUART_IntClear() prior to enabling the interrupt.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block. [in] flags
LEUART interrupt sources to enable. Use a bitwise logic OR combination of valid interrupt flags for LEUART module (LEUART_IF_nnn).
◆ LEUART_IntGet()
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inline |
Get pending LEUART interrupt flags.
- Note
- The event bits are not cleared by the use of this function.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block.
- Returns
- LEUART interrupt sources pending. A bitwise logic OR combination of valid interrupt flags for LEUART module (LEUART_IF_nnn).
◆ LEUART_IntGetEnabled()
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inline |
Get enabled and pending LEUART interrupt flags.
Useful for handling more interrupt sources in the same interrupt handler.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block.
- Note
- Interrupt flags are not cleared by the use of this function.
- Returns
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Pending and enabled LEUART interrupt sources. The return value is the bitwise AND combination of
- the OR combination of enabled interrupt sources in LEUARTx_IEN_nnn register (LEUARTx_IEN_nnn) and
- the OR combination of valid interrupt flags of LEUART module (LEUARTx_IF_nnn).
◆ LEUART_IntSet()
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inline |
Set one or more pending LEUART interrupts from SW.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block. [in] flags
LEUART interrupt sources to set to pending. Use a bitwise logic OR combination of valid interrupt flags for LEUART module (LEUART_IF_nnn).
◆ LEUART_StatusGet()
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inline |
Get LEUART STATUS register.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block.
- Returns
- STATUS register value.
◆ LEUART_RxDataGet()
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inline |
Receive one 8 bit frame, (or part of a 9 bit frame).
Used to quickly receive one 8 bit frame by reading RXDATA register directly, without checking STATUS register for RXDATAV flag. This can be useful from RXDATAV interrupt handler, i.e., waiting is superfluous, in order to quickly read received data. Please refer to LEUART_RxDataXGet() for reception of 9 bit frames.
- Note
- Since this function does not check if 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 LEUART_Rx() is normally a better choice if the validity of the RXDATA register is not certain.
- Notice that possible parity/stop bits are not considered part of specified frame bit length.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block.
- Returns
- Data received.
◆ LEUART_RxDataXGet()
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inline |
Receive one 8-9 bit frame, with extended information.
Used to quickly receive one 8-9 bit frame with extended information by reading RXDATAX register directly, without checking STATUS register for RXDATAV flag. This can be useful from RXDATAV interrupt handler, i.e., waiting is superfluous, in order to quickly read received data.
- Note
- Since this function does not check if 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 LEUART_RxExt() is normally a better choice if the validity of the RXDATAX register is not certain.
- Notice that possible parity/stop bits are not considered part of specified frame bit length.
- Parameters
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[in] leuart
Pointer to LEUART peripheral register block.
- Returns
- Data received.
Macro Definition Documentation
◆ LEUART_INIT_DEFAULT
#define LEUART_INIT_DEFAULT |
Default configuration for LEUART initialization structure.