Detailed Description

Universal Synchronous/Asynchronous Receiver/Transmitter Peripheral API.

The Universal Synchronous/Asynchronous Receiver/Transmitter (USART) is a very flexible serial I/O module. It supports full duplex asynchronous UART communication as well as RS-485, SPI, MicroWire and 3-wire. It can also interface with ISO7816 Smart-Cards, and IrDA devices.

The USART has a wide selection of operating modes, frame formats and baud rates. All features are supported through the API of this module.

Triple buffering and DMA support makes high data-rates possible with minimal CPU intervention and it is possible to transmit and receive large frames while the MCU remains in EM1 Sleep.

This module does not support DMA configuration. The UARTDRV and SPIDRV drivers provide full support for DMA and more.

The following steps are necessary for basic operation:

Clock enable:

/* USART is a HFPERCLK peripheral. Enable HFPERCLK domain and USART0.
 * We also need to enable the clock for GPIO to configure pins. */
CMU_ClockEnable(cmuClock_HFPER, true);
CMU_ClockEnable(cmuClock_USART0, true);
CMU_ClockEnable(cmuClock_GPIO, true);

To initialize the USART for asynchronous operation (eg. UART):

/* Initialize with default settings and then update fields according to application requirements. */
USART_InitAsync_TypeDef initAsync = USART_INITASYNC_DEFAULT;
initAsync.baudrate = 38400;
USART_InitAsync(USART0, &initAsync);

To initialize the USART for synchronous operation (eg. SPI):

/* Initialize with default settings and then update fields according to application requirements. */
USART_InitSync_TypeDef initSync = USART_INITSYNC_DEFAULT;
/* Operate as SPI master */
initSync.master = true;
/* Clock idle low, sample on falling edge. */
initSync.clockMode = usartClockMode1;
USART_InitSync(USART0, &initSync);

After pins are assigned for the application/board, enable pins at the desired location. Available locations can be obtained from the Pin Definitions section in the datasheet.

/* Enable I/O and set location */
USART0->ROUTE = USART_ROUTE_RXPEN | USART_ROUTE_TXPEN | USER_LOCATION;
/* Also enable CS and CLK pins if the USART is configured for synchronous mode. 
 * Set GPIO mode. */
if (USART0->CTRL & USART_CTRL_SYNC)
{  
  USART0->ROUTE |= USART_ROUTE_CSPEN | USART_ROUTE_CLKPEN;
  
  GPIO_PinModeSet((GPIO_Port_TypeDef)AF_USART0_TX_PORT(USER_LOCATION), AF_USART0_TX_PIN(USER_LOCATION), gpioModePushPull, 0);
  GPIO_PinModeSet((GPIO_Port_TypeDef)AF_USART0_RX_PORT(USER_LOCATION), AF_USART0_RX_PIN(USER_LOCATION), gpioModeInput, 0);
  GPIO_PinModeSet((GPIO_Port_TypeDef)AF_USART0_CS_PORT(USER_LOCATION), AF_USART0_CS_PIN(USER_LOCATION), gpioModePushPull, 0);
  GPIO_PinModeSet((GPIO_Port_TypeDef)AF_USART0_CLK_PORT(USER_LOCATION), AF_USART0_CLK_PIN(USER_LOCATION), gpioModePushPull, 0);
}
else
{
  /* To avoid false start, configure TX pin as initial high */
  GPIO_PinModeSet((GPIO_Port_TypeDef)AF_USART0_TX_PORT(USER_LOCATION), AF_USART0_TX_PIN(USER_LOCATION), gpioModePushPull, 1);
  GPIO_PinModeSet((GPIO_Port_TypeDef)AF_USART0_RX_PORT(USER_LOCATION), AF_USART0_RX_PIN(USER_LOCATION), gpioModeInput, 0);
  /* Don't enable CTS/RTS hardware flow control pins in this example. */
}

Note: UART hardware flow control is not directly supported in hardware on _SILICON_LABS_32B_SERIES_0 parts.; UARTDRV supports all types of UART flow control. Software assisted hardware flow control is available for parts without true UART hardware flow control.

Data Structures
struct	USART_InitAsync_TypeDef

struct	USART_InitIrDA_TypeDef

struct	USART_InitSync_TypeDef

struct	USART_PrsTriggerInit_TypeDef

Macros
#define	USART_INITASYNC_DEFAULT

#define	USART_INITIRDA_DEFAULT

#define	USART_INITPRSTRIGGER_DEFAULT

#define	USART_INITSYNC_DEFAULT

Enumerations
enum	USART_ClockMode_TypeDef { usartClockMode0 = USART_CTRL_CLKPOL_IDLELOW \| USART_CTRL_CLKPHA_SAMPLELEADING, usartClockMode1 = USART_CTRL_CLKPOL_IDLELOW \| USART_CTRL_CLKPHA_SAMPLETRAILING, usartClockMode2 = USART_CTRL_CLKPOL_IDLEHIGH \| USART_CTRL_CLKPHA_SAMPLELEADING, usartClockMode3 = USART_CTRL_CLKPOL_IDLEHIGH \| USART_CTRL_CLKPHA_SAMPLETRAILING }

enum	USART_Databits_TypeDef { usartDatabits4 = USART_FRAME_DATABITS_FOUR, usartDatabits5 = USART_FRAME_DATABITS_FIVE, usartDatabits6 = USART_FRAME_DATABITS_SIX, usartDatabits7 = USART_FRAME_DATABITS_SEVEN, usartDatabits8 = USART_FRAME_DATABITS_EIGHT, usartDatabits9 = USART_FRAME_DATABITS_NINE, usartDatabits10 = USART_FRAME_DATABITS_TEN, usartDatabits11 = USART_FRAME_DATABITS_ELEVEN, usartDatabits12 = USART_FRAME_DATABITS_TWELVE, usartDatabits13 = USART_FRAME_DATABITS_THIRTEEN, usartDatabits14 = USART_FRAME_DATABITS_FOURTEEN, usartDatabits15 = USART_FRAME_DATABITS_FIFTEEN, usartDatabits16 = USART_FRAME_DATABITS_SIXTEEN }

enum	USART_Enable_TypeDef { usartDisable = 0x0, usartEnableRx = USART_CMD_RXEN, usartEnableTx = USART_CMD_TXEN, usartEnable = (USART_CMD_RXEN \| USART_CMD_TXEN) }

enum	USART_IrDAPrsSel_Typedef { usartIrDAPrsCh0 = USART_IRCTRL_IRPRSSEL_PRSCH0, usartIrDAPrsCh1 = USART_IRCTRL_IRPRSSEL_PRSCH1, usartIrDAPrsCh2 = USART_IRCTRL_IRPRSSEL_PRSCH2, usartIrDAPrsCh3 = USART_IRCTRL_IRPRSSEL_PRSCH3, usartIrDAPrsCh4 = USART_IRCTRL_IRPRSSEL_PRSCH4, usartIrDAPrsCh5 = USART_IRCTRL_IRPRSSEL_PRSCH5, usartIrDAPrsCh6 = USART_IRCTRL_IRPRSSEL_PRSCH6, usartIrDAPrsCh7 = USART_IRCTRL_IRPRSSEL_PRSCH7 }

enum	USART_IrDAPw_Typedef { usartIrDAPwONE = USART_IRCTRL_IRPW_ONE, usartIrDAPwTWO = USART_IRCTRL_IRPW_TWO, usartIrDAPwTHREE = USART_IRCTRL_IRPW_THREE, usartIrDAPwFOUR = USART_IRCTRL_IRPW_FOUR }

enum	USART_OVS_TypeDef { usartOVS16 = USART_CTRL_OVS_X16, usartOVS8 = USART_CTRL_OVS_X8, usartOVS6 = USART_CTRL_OVS_X6, usartOVS4 = USART_CTRL_OVS_X4 }

enum	USART_Parity_TypeDef { usartNoParity = USART_FRAME_PARITY_NONE, usartEvenParity = USART_FRAME_PARITY_EVEN, usartOddParity = USART_FRAME_PARITY_ODD }

enum	USART_PrsTriggerCh_TypeDef { usartPrsTriggerCh0 = USART_TRIGCTRL_TSEL_PRSCH0, usartPrsTriggerCh1 = USART_TRIGCTRL_TSEL_PRSCH1, usartPrsTriggerCh2 = USART_TRIGCTRL_TSEL_PRSCH2, usartPrsTriggerCh3 = USART_TRIGCTRL_TSEL_PRSCH3, usartPrsTriggerCh4 = USART_TRIGCTRL_TSEL_PRSCH4, usartPrsTriggerCh5 = USART_TRIGCTRL_TSEL_PRSCH5, usartPrsTriggerCh6 = USART_TRIGCTRL_TSEL_PRSCH6, usartPrsTriggerCh7 = USART_TRIGCTRL_TSEL_PRSCH7 }

enum	USART_Stopbits_TypeDef { usartStopbits0p5 = USART_FRAME_STOPBITS_HALF, usartStopbits1 = USART_FRAME_STOPBITS_ONE, usartStopbits1p5 = USART_FRAME_STOPBITS_ONEANDAHALF, usartStopbits2 = USART_FRAME_STOPBITS_TWO }

Functions
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 specified baudrate). More...

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). More...

uint32_t	USART_BaudrateGet (USART_TypeDef *usart)
	Get current baudrate for USART/UART. More...

void	USART_BaudrateSyncSet (USART_TypeDef *usart, uint32_t refFreq, uint32_t baudrate)
	Configure USART operating in synchronous mode to use a given baudrate (or as close as possible to specified baudrate). More...

void	USART_Enable (USART_TypeDef *usart, USART_Enable_TypeDef enable)
	Enable/disable USART/UART receiver and/or transmitter. More...

void	USART_InitAsync (USART_TypeDef usart, const USART_InitAsync_TypeDef init)
	Init USART/UART for normal asynchronous mode. More...

__STATIC_INLINE void	USART_InitIrDA (const USART_InitIrDA_TypeDef *init)
	Init DEFAULT_IRDA_USART for asynchronous IrDA mode. More...

void	USART_InitPrsTrigger (USART_TypeDef usart, const USART_PrsTriggerInit_TypeDef init)
	Initialize automatic transmissions using PRS channel as trigger. More...

void	USART_InitSync (USART_TypeDef usart, const USART_InitSync_TypeDef init)
	Init USART for synchronous mode. More...

__STATIC_INLINE void	USART_IntClear (USART_TypeDef *usart, uint32_t flags)
	Clear one or more pending USART interrupts. More...

__STATIC_INLINE void	USART_IntDisable (USART_TypeDef *usart, uint32_t flags)
	Disable one or more USART interrupts. More...

__STATIC_INLINE void	USART_IntEnable (USART_TypeDef *usart, uint32_t flags)
	Enable one or more USART interrupts. More...

__STATIC_INLINE uint32_t	USART_IntGet (USART_TypeDef *usart)
	Get pending USART interrupt flags. More...

__STATIC_INLINE 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. More...

__STATIC_INLINE void	USART_IntSet (USART_TypeDef *usart, uint32_t flags)
	Set one or more pending USART interrupts from SW. More...

void	USART_Reset (USART_TypeDef *usart)
	Reset USART/UART to same state as after a HW reset. More...

uint8_t	USART_Rx (USART_TypeDef *usart)
	Receive one 4-8 bit frame, (or part of 10-16 bit frame). More...

__STATIC_INLINE uint8_t	USART_RxDataGet (USART_TypeDef *usart)
	Receive one 4-8 bit frame, (or part of 10-16 bit frame). More...

__STATIC_INLINE uint16_t	USART_RxDataXGet (USART_TypeDef *usart)
	Receive one 4-9 bit frame, (or part of 10-16 bit frame) with extended information. More...

uint16_t	USART_RxDouble (USART_TypeDef *usart)
	Receive two 4-8 bit frames, or one 10-16 bit frame. More...

uint32_t	USART_RxDoubleExt (USART_TypeDef *usart)
	Receive two 4-9 bit frames, or one 10-16 bit frame with extended information. More...

__STATIC_INLINE uint16_t	USART_RxDoubleGet (USART_TypeDef *usart)
	Receive two 4-8 bit frames, or one 10-16 bit frame. More...

__STATIC_INLINE uint32_t	USART_RxDoubleXGet (USART_TypeDef *usart)
	Receive two 4-9 bit frames, or one 10-16 bit frame with extended information. More...

uint16_t	USART_RxExt (USART_TypeDef *usart)
	Receive one 4-9 bit frame, (or part of 10-16 bit frame) with extended information. More...

uint8_t	USART_SpiTransfer (USART_TypeDef *usart, uint8_t data)
	Perform one 8 bit frame SPI transfer. More...

__STATIC_INLINE uint32_t	USART_StatusGet (USART_TypeDef *usart)
	Get USART STATUS register. More...

void	USART_Tx (USART_TypeDef *usart, uint8_t data)
	Transmit one 4-9 bit frame. More...

void	USART_TxDouble (USART_TypeDef *usart, uint16_t data)
	Transmit two 4-9 bit frames, or one 10-16 bit frame. More...

void	USART_TxDoubleExt (USART_TypeDef *usart, uint32_t data)
	Transmit two 4-9 bit frames, or one 10-16 bit frame with extended control. More...

void	USART_TxExt (USART_TypeDef *usart, uint16_t data)
	Transmit one 4-9 bit frame with extended control. More...

void	USARTn_InitIrDA (USART_TypeDef usart, const USART_InitIrDA_TypeDef init)
	Init USART for asynchronous IrDA mode. More...

Macro Definition Documentation

#define USART_INITASYNC_DEFAULT

Value:

{                                                                                          \
  usartEnable,      /* Enable RX/TX when init completed. */                                \
  0,                /* Use current configured reference clock for configuring baudrate. */ \
  115200,           /* 115200 bits/s. */                                                   \
  usartOVS16,       /* 16x oversampling. */                                                \
  usartDatabits8,   /* 8 databits. */                                                      \
  usartNoParity,    /* No parity. */                                                       \
  usartStopbits1    /* 1 stopbit. */                                                       \
}

Default config for USART async init structure.

Definition at line 387 of file em_usart.h.

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

#define USART_INITIRDA_DEFAULT

Value:

{                                                                                           \
  {                                                                                         \
    usartEnable,     /* Enable RX/TX when init completed. */                                \
    0,               /* Use current configured reference clock for configuring baudrate. */ \
    115200,          /* 115200 bits/s. */                                                   \
    usartOVS16,      /* 16x oversampling. */                                                \
    usartDatabits8,  /* 8 databits. */                                                      \
    usartEvenParity, /* Even parity. */                                                     \
    usartStopbits1   /* 1 stopbit. */                                                       \
  },                                                                                        \
  false,             /* Rx invert disabled. */                                              \
  false,             /* Filtering disabled. */                                              \
  usartIrDAPwTHREE,  /* Pulse width is set to ONE. */                                       \
  false,             /* Routing to PRS is disabled. */                                      \
  usartIrDAPrsCh0    /* PRS channel 0. */                                                   \
}

Default config for IrDA mode init structure.

Definition at line 584 of file em_usart.h.

#define USART_INITPRSTRIGGER_DEFAULT

Value:

{                                                                                          \
  false,              /* Do not enable receive triggering. */                              \
  false,              /* Do not enable transmit triggering. */                             \
  usartPrsTriggerCh0  /* Set default channel to zero. */                                   \
}

Default config for USART PRS triggering structure.

Definition at line 409 of file em_usart.h.

#define USART_INITSYNC_DEFAULT

Value:

{                                                                                           \
  usartEnable,       /* Enable RX/TX when init completed. */                                \
  0,                 /* Use current configured reference clock for configuring baudrate. */ \
  1000000,           /* 1 Mbits/s. */                                                       \
  usartDatabits8,    /* 8 databits. */                                                      \
  true,              /* Master mode. */                                                     \
  false,             /* Send least significant bit first. */                                \
  usartClockMode0    /* Clock idle low, sample on rising edge. */                           \
}

Default config for USART sync init structure.

Definition at line 498 of file em_usart.h.

Referenced by MICROSD_Init(), and SPIDRV_Init().

Enumeration Type Documentation

enum USART_ClockMode_TypeDef

Clock polarity/phase mode.

Enumerator
usartClockMode0	Clock idle low, sample on rising edge.
usartClockMode1	Clock idle low, sample on falling edge.
usartClockMode2	Clock idle high, sample on falling edge.
usartClockMode3	Clock idle high, sample on rising edge.

Definition at line 170 of file em_usart.h.

enum USART_Databits_TypeDef

Databit selection.

Enumerator
usartDatabits4	4 databits (not available for UART).
usartDatabits5	5 databits (not available for UART).
usartDatabits6	6 databits (not available for UART).
usartDatabits7	7 databits (not available for UART).
usartDatabits8	8 databits.
usartDatabits9	9 databits.
usartDatabits10	10 databits (not available for UART).
usartDatabits11	11 databits (not available for UART).
usartDatabits12	12 databits (not available for UART).
usartDatabits13	13 databits (not available for UART).
usartDatabits14	14 databits (not available for UART).
usartDatabits15	15 databits (not available for UART).
usartDatabits16	16 databits (not available for UART).

Definition at line 105 of file em_usart.h.

enum USART_Enable_TypeDef

Enable selection.

Enumerator
usartDisable	Disable both receiver and transmitter.
usartEnableRx	Enable receiver only, transmitter disabled.
usartEnableTx	Enable transmitter only, receiver disabled.
usartEnable	Enable both receiver and transmitter.

Definition at line 124 of file em_usart.h.

enum USART_IrDAPrsSel_Typedef

PRS channel selection for IrDA mode.

Enumerator
usartIrDAPrsCh0	PRS channel 0
usartIrDAPrsCh1	PRS channel 1
usartIrDAPrsCh2	PRS channel 2
usartIrDAPrsCh3	PRS channel 3
usartIrDAPrsCh4	PRS channel 4
usartIrDAPrsCh5	PRS channel 5
usartIrDAPrsCh6	PRS channel 6
usartIrDAPrsCh7	PRS channel 7

Definition at line 204 of file em_usart.h.

enum USART_IrDAPw_Typedef

Pulse width selection for IrDA mode.

Enumerator
usartIrDAPwONE	IrDA pulse width is 1/16 for OVS=0 and 1/8 for OVS=1
usartIrDAPwTWO	IrDA pulse width is 2/16 for OVS=0 and 2/8 for OVS=1
usartIrDAPwTHREE	IrDA pulse width is 3/16 for OVS=0 and 3/8 for OVS=1
usartIrDAPwFOUR	IrDA pulse width is 4/16 for OVS=0 and 4/8 for OVS=1

Definition at line 187 of file em_usart.h.

enum USART_OVS_TypeDef

Oversampling selection, used for asynchronous operation.

Enumerator
usartOVS16	16x oversampling (normal).
usartOVS8	8x oversampling.
usartOVS6	6x oversampling.
usartOVS4	4x oversampling.

Definition at line 141 of file em_usart.h.

enum USART_Parity_TypeDef

Parity selection, mainly used for asynchronous operation.

Enumerator
usartNoParity	No parity.
usartEvenParity	Even parity.
usartOddParity	Odd parity.

Definition at line 151 of file em_usart.h.

enum USART_PrsTriggerCh_TypeDef

USART PRS Transmit Trigger Channels

Enumerator
usartPrsTriggerCh0	PRSCH0 selected as USART Trigger
usartPrsTriggerCh1	PRSCH0 selected as USART Trigger
usartPrsTriggerCh2	PRSCH0 selected as USART Trigger
usartPrsTriggerCh3	PRSCH0 selected as USART Trigger
usartPrsTriggerCh4	PRSCH0 selected as USART Trigger
usartPrsTriggerCh5	PRSCH0 selected as USART Trigger
usartPrsTriggerCh6	PRSCH0 selected as USART Trigger
usartPrsTriggerCh7	PRSCH0 selected as USART Trigger

Definition at line 272 of file em_usart.h.

enum USART_Stopbits_TypeDef

Stopbits selection, used for asynchronous operation.

Enumerator
usartStopbits0p5	0.5 stopbits.
usartStopbits1	1 stopbits.
usartStopbits1p5	1.5 stopbits.
usartStopbits2	2 stopbits.

Definition at line 160 of file em_usart.h.

Function Documentation

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 specified baudrate).

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	refFreq	USART/UART reference clock frequency in Hz that will be used. If set to 0, the currently configured reference clock is assumed.
[in]	baudrate	Baudrate to try to achieve for USART/UART.
[in]	ovs	Oversampling to be used. Normal is 16x oversampling, but lower oversampling may be used to achieve higher rates or better baudrate accuracy in some cases. Notice that lower oversampling frequency makes channel more vulnerable to bit faults during reception due to clock inaccuracies compared to link partner.

Definition at line 164 of file em_usart.c.

References _USART_CLKDIV_DIV_MASK, _USART_CTRL_OVS_MASK, USART_TypeDef::CLKDIV, CMU_ClockFreqGet(), cmuClock_HFPER, USART_TypeDef::CTRL, usartOVS16, usartOVS4, usartOVS6, and usartOVS8.

Referenced by USART_InitAsync().

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

Parameters

[in]	refFreq	USART/UART HF peripheral frequency used.
[in]	clkdiv	Clock division factor to be used.
[in]	syncmode	true - synchronous mode operation. false - asynchronous mode operation.
[in]	ovs	Oversampling used if asynchronous mode. Not used if `syncmode` is true.

Returns: Baudrate with given settings.

Definition at line 295 of file em_usart.c.

References _USART_CLKDIV_DIV_MASK, usartOVS16, usartOVS6, and usartOVS8.

Referenced by USART_BaudrateGet().

uint32_t USART_BaudrateGet ( USART_TypeDef * usart )

Get current baudrate for USART/UART.

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

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Current baudrate.

Definition at line 431 of file em_usart.c.

References _USART_CTRL_OVS_MASK, USART_TypeDef::CLKDIV, CMU_ClockFreqGet(), cmuClock_HFPER, USART_TypeDef::CTRL, USART_BaudrateCalc(), and USART_CTRL_SYNC.

Referenced by SPIDRV_GetBitrate().

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

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

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

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

Parameters

[in]	usart	Pointer to USART peripheral register block. (Cannot be used on UART modules.)
[in]	refFreq	USART reference clock frequency in Hz that will be used. If set to 0, the currently configured reference clock is assumed.
[in]	baudrate	Baudrate to try to achieve for USART.

Definition at line 480 of file em_usart.c.

References _USART_CLKDIV_DIV_MASK, BUS_RegMaskedWrite(), USART_TypeDef::CLKDIV, CMU_ClockFreqGet(), and cmuClock_HFPER.

Referenced by MICROSD_SpiClkFast(), MICROSD_SpiClkSlow(), SPIDRV_SetBitrate(), and USART_InitSync().

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 is done (if not enabled as part of init).

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	enable	Select status for receiver/transmitter.

Definition at line 527 of file em_usart.c.

References _USART_CMD_RXEN_MASK, _USART_CMD_TXEN_MASK, and USART_TypeDef::CMD.

Referenced by RETARGET_SerialInit(), and UARTDRV_InitUart().

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

Init USART/UART for normal asynchronous mode.

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

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, in order for the USART/UART 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.)

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	init	Pointer to initialization structure used to configure basic async setup.

Definition at line 569 of file em_usart.c.

References USART_InitAsync_TypeDef::baudrate, USART_TypeDef::CMD, USART_TypeDef::CTRL, USART_InitAsync_TypeDef::databits, USART_InitAsync_TypeDef::enable, USART_TypeDef::FRAME, USART_InitAsync_TypeDef::oversampling, USART_InitAsync_TypeDef::parity, USART_InitAsync_TypeDef::refFreq, USART_InitAsync_TypeDef::stopbits, USART_BaudrateAsyncSet(), USART_CTRL_AUTOCS, and USART_Reset().

Referenced by BSP_BccInit(), RETARGET_SerialInit(), UARTDRV_InitUart(), and USARTn_InitIrDA().

__STATIC_INLINE void USART_InitIrDA ( const USART_InitIrDA_TypeDef * init )

Init DEFAULT_IRDA_USART for asynchronous IrDA mode.

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

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, in order for the USART/UART 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.)

Parameters

[in] init Pointer to initialization structure used to configure async IrDA setup.

Deprecated:: Deprecated function. New code should use USARTn_InitIrDA(). This function uses DEFAULT_IRDA_USART, which unless otherwise specified, is USART0 on most devices, and USART1 on devices that don't have a USART0.

Definition at line 733 of file em_usart.h.

References USART0, USART1, and USARTn_InitIrDA().

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

Initialize automatic transmissions using PRS channel as trigger.

Note: Initialize USART with USART_Init() before setting up PRS configuration

Parameters

[in]	usart	Pointer to USART to configure
[in]	init	Pointer to initialization structure

Definition at line 816 of file em_usart.c.

References _USART_TRIGCTRL_RXTEN_MASK, _USART_TRIGCTRL_TSEL_MASK, _USART_TRIGCTRL_TXTEN_MASK, USART_PrsTriggerInit_TypeDef::prsTriggerChannel, USART_PrsTriggerInit_TypeDef::rxTriggerEnable, USART_TypeDef::TRIGCTRL, USART_PrsTriggerInit_TypeDef::txTriggerEnable, USART_TRIGCTRL_RXTEN, and USART_TRIGCTRL_TXTEN.

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

Init USART for synchronous mode.

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

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, in order for the USART 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.)

Parameters

[in]	usart	Pointer to USART peripheral register block. (UART does not support this mode.)
[in]	init	Pointer to initialization structure used to configure basic async setup.

Definition at line 640 of file em_usart.c.

References USART_InitSync_TypeDef::baudrate, USART_InitSync_TypeDef::clockMode, USART_TypeDef::CMD, USART_TypeDef::CTRL, USART_InitSync_TypeDef::databits, USART_InitSync_TypeDef::enable, USART_TypeDef::FRAME, USART_InitSync_TypeDef::master, USART_InitSync_TypeDef::msbf, USART_InitSync_TypeDef::refFreq, USART_BaudrateSyncSet(), USART_CMD_MASTEREN, USART_CTRL_AUTOCS, USART_CTRL_MSBF, USART_CTRL_SYNC, USART_FRAME_PARITY_DEFAULT, USART_FRAME_STOPBITS_DEFAULT, and USART_Reset().

Referenced by ICM20648_spiInit(), MICROSD_Init(), SPI_TFT_Init(), and SPIDRV_Init().

__STATIC_INLINE void USART_IntClear	(	USART_TypeDef *	usart,
		uint32_t	flags
	)

Clear one or more pending USART interrupts.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	flags	Pending USART/UART interrupt source(s) to clear. Use one or more valid interrupt flags for the USART module (USART_IF_nnn) OR'ed together.

Definition at line 757 of file em_usart.h.

References USART_TypeDef::IFC.

Referenced by RETARGET_SerialInit(), and UARTDRV_InitUart().

__STATIC_INLINE void USART_IntDisable	(	USART_TypeDef *	usart,
		uint32_t	flags
	)

Disable one or more USART interrupts.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	flags	USART/UART interrupt source(s) to disable. Use one or more valid interrupt flags for the USART module (USART_IF_nnn) OR'ed together.

Definition at line 774 of file em_usart.h.

References USART_TypeDef::IEN.

__STATIC_INLINE 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. Consider using USART_IntClear() prior to enabling if such a pending interrupt should be ignored.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	flags	USART/UART interrupt source(s) to enable. Use one or more valid interrupt flags for the USART module (USART_IF_nnn) OR'ed together.

Definition at line 796 of file em_usart.h.

References USART_TypeDef::IEN.

Referenced by RETARGET_SerialInit().

__STATIC_INLINE 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.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

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

Definition at line 816 of file em_usart.h.

References USART_TypeDef::IF.

__STATIC_INLINE 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.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

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).

Definition at line 841 of file em_usart.h.

References USART_TypeDef::IEN, and USART_TypeDef::IF.

__STATIC_INLINE void USART_IntSet	(	USART_TypeDef *	usart,
		uint32_t	flags
	)

Set one or more pending USART interrupts from SW.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	flags	USART/UART interrupt source(s) to set to pending. Use one or more valid interrupt flags for the USART module (USART_IF_nnn) OR'ed together.

Definition at line 865 of file em_usart.h.

References USART_TypeDef::IFS.

void USART_Reset ( USART_TypeDef * usart )

Reset USART/UART to same state as after a HW reset.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Definition at line 856 of file em_usart.c.

References _USART_CLKDIV_RESETVALUE, _USART_CTRL_RESETVALUE, _USART_FRAME_RESETVALUE, _USART_IEN_RESETVALUE, _USART_IFC_MASK, _USART_IRCTRL_RESETVALUE, _USART_ROUTE_RESETVALUE, _USART_TRIGCTRL_RESETVALUE, USART_TypeDef::CLKDIV, USART_TypeDef::CMD, USART_TypeDef::CTRL, USART_TypeDef::FRAME, USART_TypeDef::IEN, USART_TypeDef::IFC, USART_TypeDef::IRCTRL, USART_TypeDef::ROUTE, USART_TypeDef::TRIGCTRL, USART_CMD_CLEARRX, USART_CMD_CLEARTX, USART_CMD_MASTERDIS, USART_CMD_RXBLOCKDIS, USART_CMD_RXDIS, USART_CMD_TXDIS, and USART_CMD_TXTRIDIS.

Referenced by BOARD_flashDeepPowerDown(), BSP_BccDeInit(), ICM20648_spiInit(), MICROSD_Deinit(), SPI_TFT_Init(), SPIDRV_DeInit(), USART_InitAsync(), and USART_InitSync().

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

Notice that possible parity/stop bits in asynchronous mode are not considered part of 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, and if data is avaliable, call USART_RxDataGet() to read the RXDATA register directly.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 923 of file em_usart.c.

References USART_TypeDef::RXDATA, USART_TypeDef::STATUS, and USART_STATUS_RXDATAV.

Referenced by ICM20648_bankSelect(), ICM20648_registerRead(), ICM20648_registerWrite(), and SPI_TFT_WriteRegister().

__STATIC_INLINE 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: 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 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.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 922 of file em_usart.h.

References USART_TypeDef::RXDATA.

__STATIC_INLINE 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: 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 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.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 1031 of file em_usart.h.

References USART_TypeDef::RXDATAX.

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

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 empty, until data is received. Alternatively the user can explicitly check whether data is available, and if data is avaliable, call USART_RxDoubleGet() to read the RXDOUBLE register directly.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 956 of file em_usart.c.

References USART_TypeDef::RXDOUBLE, USART_TypeDef::STATUS, and USART_STATUS_RXFULL.

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 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, and if data is avaliable, call USART_RxDoubleXGet() to read the RXDOUBLEX register directly.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 989 of file em_usart.c.

References USART_TypeDef::RXDOUBLEX, USART_TypeDef::STATUS, and USART_STATUS_RXFULL.

__STATIC_INLINE 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: Since 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. like 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.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 960 of file em_usart.h.

References USART_TypeDef::RXDOUBLE.

__STATIC_INLINE 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: Since 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. like 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.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 996 of file em_usart.h.

References USART_TypeDef::RXDOUBLEX.

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 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, and if data is avaliable, call USART_RxDataXGet() to read the RXDATAX register directly.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: Data received.

Definition at line 1022 of file em_usart.c.

References USART_TypeDef::RXDATAX, USART_TypeDef::STATUS, and USART_STATUS_RXDATAV.

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 the data is fully transmitted. The SPI return value is then read out and returned.

Parameters

[in]	usart	Pointer to USART peripheral register block.
[in]	data	Data to transmit.

Returns: Data received.

Definition at line 1050 of file em_usart.c.

References USART_TypeDef::RXDATA, USART_TypeDef::STATUS, USART_TypeDef::TXDATA, USART_STATUS_TXBL, and USART_STATUS_TXC.

Referenced by BOARD_flashDeepPowerDown(), and MICROSD_XferSpi().

__STATIC_INLINE uint32_t USART_StatusGet ( USART_TypeDef * usart )

Get USART STATUS register.

Parameters

[in] usart Pointer to USART/UART peripheral register block.

Returns: STATUS register value.

Definition at line 882 of file em_usart.h.

References USART_TypeDef::STATUS.

void USART_Tx	(	USART_TypeDef *	usart,
		uint8_t	data
	)

Transmit one 4-9 bit frame.

Depending on frame length configuration, 4-8 (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 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 specified frame bit length.

Note: This function will stall if buffer is full, until buffer becomes available.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	data	Data to transmit. See details above for further info.

Definition at line 1084 of file em_usart.c.

References USART_TypeDef::STATUS, USART_TypeDef::TXDATA, and USART_STATUS_TXBL.

Referenced by ICM20648_bankSelect(), ICM20648_registerRead(), ICM20648_registerWrite(), SPI_TFT_WriteRegister(), and UARTDRV_ForceTransmit().

void USART_TxDouble	(	USART_TypeDef *	usart,
		uint16_t	data
	)

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

Depending on 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 CTRL register, BIT8DV field, to each byte. Please refer to USART_TxDoubleExt() for transmitting two 9 bit frames with full control of all 9 bits.

If 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 specified frame bit length.

Note: This function will stall if buffer is full, until buffer becomes available.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	data	Data to transmit, the least significant byte holds the frame transmitted first. See details above for further info.

Definition at line 1120 of file em_usart.c.

References USART_TypeDef::STATUS, USART_TypeDef::TXDOUBLE, and USART_STATUS_TXBL.

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 specified frame bit length.

Note: This function will stall if buffer is full, until buffer becomes available.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	data	Data to transmit with extended control. Contains two 16 bit words concatenated. Least significant word holds frame transitted first. If frame length is 4-9, two frames with 4-9 least significant bits from each 16 bit word are transmitted.

: If 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.

Definition at line 1156 of file em_usart.c.

References USART_TypeDef::STATUS, USART_TypeDef::TXDOUBLEX, and USART_STATUS_TXBL.

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 specified frame bit length.

Note: This function will stall if buffer is full, until buffer becomes available.

Parameters

[in]	usart	Pointer to USART/UART peripheral register block.
[in]	data	Data 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 1184 of file em_usart.c.

References USART_TypeDef::STATUS, USART_TypeDef::TXDATAX, and USART_STATUS_TXBL.

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

Init USART for asynchronous IrDA mode.

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

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, in order for the USART/UART 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.)

Parameters

[in]	usart	Pointer to USART peripheral register block.
[in]	init	Pointer to initialization structure used to configure async IrDA setup.

Note: Not all USART instances support IrDA. See the datasheet for your device.

Definition at line 721 of file em_usart.c.

References _USART_IRCTRL_IRFILT_SHIFT, _USART_IRCTRL_IRPRSEN_SHIFT, USART_InitIrDA_TypeDef::async, USART_TypeDef::CTRL, USART_TypeDef::IRCTRL, USART_InitIrDA_TypeDef::irFilt, USART_InitIrDA_TypeDef::irPrsEn, USART_InitIrDA_TypeDef::irPrsSel, USART_InitIrDA_TypeDef::irPw, USART_InitIrDA_TypeDef::irRxInv, USART_CTRL_RXINV, USART_CTRL_TXINV, USART_InitAsync(), and USART_IRCTRL_IREN.

Referenced by USART_InitIrDA().

Detailed Description

Data Structures

Macros

Enumerations

Functions

Macro Definition Documentation

Enumeration Type Documentation

Function Documentation