EFM32 Happy Gecko Software Documentation  efm32hg-doc-5.1.2
LEUART

Detailed 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 provides full UART communication using a low frequency 32.768 kHz clock, and has special features for communication without CPU intervention.

Data Structures

struct  LEUART_Init_TypeDef
 

Macros

#define LEUART_INIT_DEFAULT
 

Enumerations

enum  LEUART_Databits_TypeDef {
  leuartDatabits8 = LEUART_CTRL_DATABITS_EIGHT,
  leuartDatabits9 = LEUART_CTRL_DATABITS_NINE
}
 
enum  LEUART_Enable_TypeDef {
  leuartDisable = 0x0,
  leuartEnableRx = LEUART_CMD_RXEN,
  leuartEnableTx = LEUART_CMD_TXEN,
  leuartEnable = (LEUART_CMD_RXEN | LEUART_CMD_TXEN)
}
 
enum  LEUART_Parity_TypeDef {
  leuartNoParity = LEUART_CTRL_PARITY_NONE,
  leuartEvenParity = LEUART_CTRL_PARITY_EVEN,
  leuartOddParity = LEUART_CTRL_PARITY_ODD
}
 
enum  LEUART_Stopbits_TypeDef {
  leuartStopbits1 = LEUART_CTRL_STOPBITS_ONE,
  leuartStopbits2 = LEUART_CTRL_STOPBITS_TWO
}
 

Functions

uint32_t LEUART_BaudrateCalc (uint32_t refFreq, uint32_t clkdiv)
 Calculate baudrate for LEUART given reference frequency and clock division. More...
 
uint32_t LEUART_BaudrateGet (LEUART_TypeDef *leuart)
 Get current baudrate for LEUART. More...
 
void LEUART_BaudrateSet (LEUART_TypeDef *leuart, uint32_t refFreq, uint32_t baudrate)
 Configure baudrate (or as close as possible to specified baudrate). More...
 
void LEUART_Enable (LEUART_TypeDef *leuart, LEUART_Enable_TypeDef enable)
 Enable/disable LEUART receiver and/or transmitter. More...
 
void LEUART_FreezeEnable (LEUART_TypeDef *leuart, bool enable)
 LEUART register synchronization freeze control. More...
 
void LEUART_Init (LEUART_TypeDef *leuart, LEUART_Init_TypeDef const *init)
 Init LEUART. More...
 
__STATIC_INLINE void LEUART_IntClear (LEUART_TypeDef *leuart, uint32_t flags)
 Clear one or more pending LEUART interrupts. More...
 
__STATIC_INLINE void LEUART_IntDisable (LEUART_TypeDef *leuart, uint32_t flags)
 Disable one or more LEUART interrupts. More...
 
__STATIC_INLINE void LEUART_IntEnable (LEUART_TypeDef *leuart, uint32_t flags)
 Enable one or more LEUART interrupts. More...
 
__STATIC_INLINE uint32_t LEUART_IntGet (LEUART_TypeDef *leuart)
 Get pending LEUART interrupt flags. More...
 
__STATIC_INLINE uint32_t LEUART_IntGetEnabled (LEUART_TypeDef *leuart)
 Get enabled and pending LEUART interrupt flags. Useful for handling more interrupt sources in the same interrupt handler. More...
 
__STATIC_INLINE void LEUART_IntSet (LEUART_TypeDef *leuart, uint32_t flags)
 Set one or more pending LEUART interrupts from SW. More...
 
void LEUART_Reset (LEUART_TypeDef *leuart)
 Reset LEUART to same state as after a HW reset. More...
 
uint8_t LEUART_Rx (LEUART_TypeDef *leuart)
 Receive one 8 bit frame, (or part of 9 bit frame). More...
 
__STATIC_INLINE uint8_t LEUART_RxDataGet (LEUART_TypeDef *leuart)
 Receive one 8 bit frame, (or part of a 9 bit frame). More...
 
__STATIC_INLINE uint16_t LEUART_RxDataXGet (LEUART_TypeDef *leuart)
 Receive one 8-9 bit frame, with extended information. More...
 
void LEUART_RxDmaInEM2Enable (LEUART_TypeDef *leuart, bool enable)
 Enables handling of LEUART RX by DMA in EM2. More...
 
uint16_t LEUART_RxExt (LEUART_TypeDef *leuart)
 Receive one 8-9 bit frame, with extended information. More...
 
__STATIC_INLINE uint32_t LEUART_StatusGet (LEUART_TypeDef *leuart)
 Get LEUART STATUS register. More...
 
void LEUART_Tx (LEUART_TypeDef *leuart, uint8_t data)
 Transmit one frame. More...
 
void LEUART_TxDmaInEM2Enable (LEUART_TypeDef *leuart, bool enable)
 Enables handling of LEUART TX by DMA in EM2. More...
 
void LEUART_TxExt (LEUART_TypeDef *leuart, uint16_t data)
 Transmit one 8-9 bit frame with extended control. More...
 

Macro Definition Documentation

#define LEUART_INIT_DEFAULT
Value:
{ \
leuartEnable, /* Enable RX/TX when init completed. */ \
0, /* Use current configured reference clock for configuring baudrate. */ \
9600, /* 9600 bits/s. */ \
leuartDatabits8, /* 8 databits. */ \
leuartNoParity, /* No parity. */ \
leuartStopbits1 /* 1 stopbit. */ \
}

Default config for LEUART init structure.

Definition at line 132 of file em_leuart.h.

Referenced by BSP_BccInit(), RETARGET_SerialInit(), and UARTDRV_InitLeuart().

Enumeration Type Documentation

Databit selection.

Enumerator
leuartDatabits8 

8 databits.

leuartDatabits9 

9 databits.

Definition at line 61 of file em_leuart.h.

Enable selection.

Enumerator
leuartDisable 

Disable both receiver and transmitter.

leuartEnableRx 

Enable receiver only, transmitter disabled.

leuartEnableTx 

Enable transmitter only, receiver disabled.

leuartEnable 

Enable both receiver and transmitter.

Definition at line 69 of file em_leuart.h.

Parity selection.

Enumerator
leuartNoParity 

No parity.

leuartEvenParity 

Even parity.

leuartOddParity 

Odd parity.

Definition at line 86 of file em_leuart.h.

Stopbits selection.

Enumerator
leuartStopbits1 

1 stopbits.

leuartStopbits2 

2 stopbits.

Definition at line 95 of file em_leuart.h.

Function Documentation

uint32_t LEUART_BaudrateCalc ( uint32_t  refFreq,
uint32_t  clkdiv 
)

Calculate baudrate for 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 actual HW configuration. It can be used to determinate if a given configuration is sufficiently accurate for the application.

Parameters
[in]refFreqLEUART peripheral frequency used.
[in]clkdivClock division factor to be used.
Returns
Baudrate with given settings.

Definition at line 134 of file em_leuart.c.

References _LEUART_CLKDIV_MASK.

Referenced by LEUART_BaudrateGet().

uint32_t LEUART_BaudrateGet ( LEUART_TypeDef leuart)

Get current baudrate for LEUART.

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

Parameters
[in]leuartPointer to LEUART peripheral register block.
Returns
Current baudrate.

Definition at line 212 of file em_leuart.c.

References LEUART_TypeDef::CLKDIV, CMU_ClockFreqGet(), cmuClock_LEUART0, LEUART0, and LEUART_BaudrateCalc().

void LEUART_BaudrateSet ( LEUART_TypeDef leuart,
uint32_t  refFreq,
uint32_t  baudrate 
)

Configure baudrate (or as close as possible to specified baudrate).

Note
The setting of a baudrate 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
[in]leuartPointer to LEUART peripheral register block.
[in]refFreqLEUART reference clock frequency in Hz that will be used. If set to 0, the currently configured reference clock is assumed.
[in]baudrateBaudrate to try to achieve for LEUART.

Definition at line 260 of file em_leuart.c.

References _LEUART_CLKDIV_MASK, LEUART_TypeDef::CLKDIV, CMU_ClockFreqGet(), cmuClock_LEUART0, LEUART0, and LEUART_SYNCBUSY_CLKDIV.

Referenced by LEUART_Init().

void LEUART_Enable ( LEUART_TypeDef leuart,
LEUART_Enable_TypeDef  enable 
)

Enable/disable LEUART receiver and/or transmitter.

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

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
[in]leuartPointer to LEUART peripheral register block.
[in]enableSelect status for receiver/transmitter.

Definition at line 357 of file em_leuart.c.

References _LEUART_CMD_RXEN_MASK, _LEUART_CMD_TXEN_MASK, LEUART_TypeDef::CMD, and LEUART_SYNCBUSY_CMD.

Referenced by RETARGET_SerialInit(), and UARTDRV_InitLeuart().

void LEUART_FreezeEnable ( LEUART_TypeDef leuart,
bool  enable 
)

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 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 unecessary stalling.
Parameters
[in]leuartPointer to 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 LF domain

Definition at line 405 of file em_leuart.c.

References LEUART_TypeDef::FREEZE, LEUART_FREEZE_REGFREEZE, and LEUART_TypeDef::SYNCBUSY.

Referenced by LEUART_Init(), and LEUART_Reset().

void LEUART_Init ( LEUART_TypeDef leuart,
LEUART_Init_TypeDef const *  init 
)

Init LEUART.

This function will configure basic settings in order to operate in normal asynchronous mode. Consider using LEUART_Reset() prior to this function if 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, in order for the LEUART to work as intended. (When configuring pins, one should remember to consider the sequence of configuration, in order 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
[in]leuartPointer to LEUART peripheral register block.
[in]initPointer to initialization structure used to configure basic async setup.

Definition at line 461 of file em_leuart.c.

References _LEUART_CTRL_PARITY_MASK, _LEUART_CTRL_STOPBITS_MASK, LEUART_Init_TypeDef::baudrate, LEUART_TypeDef::CMD, LEUART_TypeDef::CTRL, LEUART_Init_TypeDef::databits, LEUART_Init_TypeDef::enable, LEUART_BaudrateSet(), LEUART_CMD_RXDIS, LEUART_CMD_TXDIS, LEUART_FreezeEnable(), LEUART_SYNCBUSY_CMD, LEUART_Init_TypeDef::parity, LEUART_Init_TypeDef::refFreq, and LEUART_Init_TypeDef::stopbits.

Referenced by BSP_BccInit(), RETARGET_SerialInit(), and UARTDRV_InitLeuart().

__STATIC_INLINE void LEUART_IntClear ( LEUART_TypeDef leuart,
uint32_t  flags 
)

Clear one or more pending LEUART interrupts.

Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]flagsPending LEUART interrupt source to clear. Use a bitwise logic OR combination of valid interrupt flags for the LEUART module (LEUART_IF_nnn).

Definition at line 169 of file em_leuart.h.

References LEUART_TypeDef::IFC.

Referenced by RETARGET_SerialInit(), and UARTDRV_InitLeuart().

__STATIC_INLINE void LEUART_IntDisable ( LEUART_TypeDef leuart,
uint32_t  flags 
)

Disable one or more LEUART interrupts.

Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]flagsLEUART interrupt sources to disable. Use a bitwise logic OR combination of valid interrupt flags for the LEUART module (LEUART_IF_nnn).

Definition at line 186 of file em_leuart.h.

References LEUART_TypeDef::IEN.

__STATIC_INLINE void LEUART_IntEnable ( LEUART_TypeDef leuart,
uint32_t  flags 
)

Enable one or more LEUART interrupts.

Note
Depending on the use, a pending interrupt may already be set prior to enabling the interrupt. Consider using LEUART_IntClear() prior to enabling if such a pending interrupt should be ignored.
Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]flagsLEUART interrupt sources to enable. Use a bitwise logic OR combination of valid interrupt flags for the LEUART module (LEUART_IF_nnn).

Definition at line 208 of file em_leuart.h.

References LEUART_TypeDef::IEN.

Referenced by RETARGET_SerialInit().

__STATIC_INLINE uint32_t LEUART_IntGet ( LEUART_TypeDef leuart)

Get pending LEUART interrupt flags.

Note
The event bits are not cleared by the use of this function.
Parameters
[in]leuartPointer to LEUART peripheral register block.
Returns
LEUART interrupt sources pending. A bitwise logic OR combination of valid interrupt flags for the LEUART module (LEUART_IF_nnn).

Definition at line 228 of file em_leuart.h.

References LEUART_TypeDef::IF.

__STATIC_INLINE uint32_t LEUART_IntGetEnabled ( LEUART_TypeDef leuart)

Get enabled and pending LEUART interrupt flags. Useful for handling more interrupt sources in the same interrupt handler.

Parameters
[in]leuartPointer to LEUART peripheral register block.
Note
Interrupt flags are not cleared by the use of this function.
Returns
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 the LEUART module (LEUARTx_IF_nnn).

Definition at line 253 of file em_leuart.h.

References LEUART_TypeDef::IEN, and LEUART_TypeDef::IF.

__STATIC_INLINE void LEUART_IntSet ( LEUART_TypeDef leuart,
uint32_t  flags 
)

Set one or more pending LEUART interrupts from SW.

Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]flagsLEUART interrupt sources to set to pending. Use a bitwise logic OR combination of valid interrupt flags for the LEUART module (LEUART_IF_nnn).

Definition at line 277 of file em_leuart.h.

References LEUART_TypeDef::IFS.

uint8_t LEUART_Rx ( LEUART_TypeDef leuart)

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. Please refer to LEUART_RxExt() for reception of 9 bit frames.

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

Note
This function will stall if buffer is empty, until data is received.
Parameters
[in]leuartPointer to LEUART peripheral register block.
Returns
Data received.

Definition at line 551 of file em_leuart.c.

References LEUART_STATUS_RXDATAV, LEUART_TypeDef::RXDATA, and LEUART_TypeDef::STATUS.

__STATIC_INLINE uint8_t LEUART_RxDataGet ( LEUART_TypeDef leuart)

Receive one 8 bit frame, (or part of a 9 bit frame).

This function is used to quickly receive one 8 bit 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 LEUART_RxDataXGet() for reception of 9 bit frames.

Note
Since 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. like 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
[in]leuartPointer to LEUART peripheral register block.
Returns
Data received.

Definition at line 334 of file em_leuart.h.

References LEUART_TypeDef::RXDATA.

__STATIC_INLINE uint16_t LEUART_RxDataXGet ( LEUART_TypeDef leuart)

Receive one 8-9 bit frame, with extended information.

This function is used to quickly receive one 8-9 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
Since 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. like 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
[in]leuartPointer to LEUART peripheral register block.
Returns
Data received.

Definition at line 368 of file em_leuart.h.

References LEUART_TypeDef::RXDATAX.

void LEUART_RxDmaInEM2Enable ( LEUART_TypeDef leuart,
bool  enable 
)

Enables handling of LEUART RX by DMA in EM2.

Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]enabletrue - enables functionality false - disables functionality

Definition at line 692 of file em_leuart.c.

References LEUART_TypeDef::CTRL, LEUART_CTRL_RXDMAWU, and LEUART_SYNCBUSY_CTRL.

uint16_t LEUART_RxExt ( LEUART_TypeDef leuart)

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
[in]leuartPointer to LEUART peripheral register block.
Returns
Data received.

Definition at line 577 of file em_leuart.c.

References LEUART_STATUS_RXDATAV, LEUART_TypeDef::RXDATAX, and LEUART_TypeDef::STATUS.

__STATIC_INLINE uint32_t LEUART_StatusGet ( LEUART_TypeDef leuart)

Get LEUART STATUS register.

Parameters
[in]leuartPointer to LEUART peripheral register block.
Returns
STATUS register value.

Definition at line 294 of file em_leuart.h.

References LEUART_TypeDef::STATUS.

void LEUART_Tx ( LEUART_TypeDef leuart,
uint8_t  data 
)

Transmit one frame.

Depending on frame length configuration, 8 (least significant) bits from data are transmitted. If frame length is 9, 8 bits are transmitted from data and one bit as specified by CTRL register, BIT8DV field. Please refer to 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 part of specified frame bit length.

Note
This function will stall if buffer is full, until buffer becomes available.
Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]dataData to transmit. See details above for further info.

Definition at line 609 of file em_leuart.c.

References LEUART_STATUS_TXBL, LEUART_SYNCBUSY_TXDATA, LEUART_TypeDef::STATUS, and LEUART_TypeDef::TXDATA.

Referenced by UARTDRV_ForceTransmit().

void LEUART_TxDmaInEM2Enable ( LEUART_TypeDef leuart,
bool  enable 
)

Enables handling of LEUART TX by DMA in EM2.

Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]enabletrue - enables functionality false - disables functionality

Definition at line 665 of file em_leuart.c.

References LEUART_TypeDef::CTRL, LEUART_CTRL_TXDMAWU, and LEUART_SYNCBUSY_CTRL.

void LEUART_TxExt ( LEUART_TypeDef leuart,
uint16_t  data 
)

Transmit one 8-9 bit frame with extended control.

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

Note
This function will stall if buffer is full, until buffer becomes available.
Parameters
[in]leuartPointer to LEUART peripheral register block.
[in]dataData to transmit with extended control. Least significant bits contains frame bits, and additional control bits are available as documented in the reference manual (set to 0 if not used).

Definition at line 641 of file em_leuart.c.

References LEUART_STATUS_TXBL, LEUART_SYNCBUSY_TXDATAX, LEUART_TypeDef::STATUS, and LEUART_TypeDef::TXDATAX.