Detailed Description

UART driver interface.

============================================================================

The UART header file should be included in an application as follows:

Operation

The UART driver simplifies reading and writing to any of the UART peripherals on the board with multiple modes of operation and performance. These include blocking, non-blocking, and polling as well as text/binary mode, echo and return characters. The board's UART pins must be configured before initializing the UART driver. The application initializes the UART driver by calling UART_init() and is then ready to open a UART by calling UART_open(), passing in a UART parameters data structure.

The APIs in this driver serve as an interface to a typical TI-RTOS application. The specific peripheral implementations are responsible to create all the SYS/BIOS specific primitives to allow for thread-safe operation.

The UART driver allows full duplex data transfers. Therefore, it is possible to call UART_read() and UART_write() at the same time (for either UART_MODE_CALLBACK and UART_MODE_BLOCKING modes). It is not possible, however, to issue multiple concurrent operations in the same direction. For example, if one thread calls UART_read(uart0, buffer0...), any other thread attempting UART_read(uart0, buffer1...) will result in an error of UART_ERROR, until all the data from the first UART_read() has been transferred to buffer0. This applies to both UART_MODE_CALLBACK and UART_MODE_BLOCKING modes. So applications must either synchronize UART_read() (or UART_write()) calls that use the same UART handle, or check for the UART_ERROR return code indicating that a transfer is still ongoing.

Opening the driver

UART_Handle      handle;
UART_Params      params;
UART_Params_init(&params);
params.baudRate  = someNewBaudRate;
params.writeDataMode = UART_DATA_BINARY;
params.readDataMode = UART_DATA_BINARY;
params.readReturnMode = UART_RETURN_FULL;
params.readEcho = UART_ECHO_OFF;
handle = UART_open(someUART_configIndexValue, &params);
if (!handle) {
    System_printf("UART did not open");
}

Writing data

const unsigned char hello[] = "Hello World\n";
ret = UART_write(handle, hello, sizeof(hello));
System_printf("The UART wrote %d bytes\n", ret);

Reading data

unsigned char rxBuffer[20];
ret = UART_read(handle, rxBuffer, sizeof(rxBuffer));
System_printf("The UART read %d bytes\n", ret);

Implementation

This module serves as the main interface for TI-RTOS applications. Its purpose is to redirect the module's APIs to specific peripheral implementations which are specified using a pointer to a UART_FxnTable.

The UART driver interface module is joined (at link time) to a NULL-terminated array of UART_Config data structures named UART_config. UART_config is implemented in the application with each entry being an instance of a UART peripheral. Each entry in UART_config contains a:

(UART_FxnTable *) to a set of functions that implement a UART peripheral
(void *) data object that is associated with the UART_FxnTable
(void *) hardware attributes that are associated with the UART_FxnTable

Stack requirements

It is STRONGLY discouraged to perform UART_read() or UART_write calls within the driver's own callback function when in UART_MODE_CALLBACK. Doing so will incur additional task or system stack size requirements. See the peripheral implementations' documentation for stack size estimations. It is expected that the user perform his/her own stack and usage analysis when choosing to nest these calls.

Instrumentation

The UART driver interface produces log statements if instrumentation is enabled.

Diagnostics Mask	Log details
Diags_USER1	basic operations performed
Diags_USER2	detailed operations performed

#include <stdint.h>
#include <stddef.h>

Include dependency graph for UART.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	UART_Params
	UART Parameters. More...

struct	UART_FxnTable
	The definition of a UART function table that contains the required set of functions to control a specific UART driver implementation. More...

struct	UART_Config
	UART Global configuration. More...

Macros
#define	UART_CMD_RESERVED 32

#define	UART_STATUS_RESERVED -32

#define	UART_STATUS_SUCCESS 0
	Successful status code returned by UART_control(). More...

#define	UART_STATUS_ERROR -1
	Generic error status code returned by UART_control(). More...

#define	UART_STATUS_UNDEFINEDCMD -2
	An error status code returned by UART_control() for undefined command codes. More...

#define	UART_CMD_PEEK 0
	Command code used by UART_control() to read the next unsigned char. More...

#define	UART_CMD_ISAVAILABLE 1
	Command code used by UART_control() to determine if the read buffer is empty. More...

#define	UART_CMD_GETRXCOUNT 2
	Command code used by UART_control() to determine how many unsigned chars are in the read buffer. More...

#define	UART_CMD_RXENABLE 3
	Command code used by UART_control() to enable data receive by the UART. More...

#define	UART_CMD_RXDISABLE 4
	Command code used by UART_control() to disable data received by the UART. More...

#define	UART_ERROR UART_STATUS_ERROR

#define	UART_WAIT_FOREVER (~0)
	Wait forever define. More...

Typedefs
typedef struct UART_Config *	UART_Handle
	A handle that is returned from a UART_open() call. More...

typedef void(*	UART_Callback) (UART_Handle, void *buf, size_t count)
	The definition of a callback function used by the UART driver when used in UART_MODE_CALLBACK The callback can occur in task or HWI context. More...

typedef enum UART_Mode	UART_Mode
	UART mode settings. More...

typedef enum UART_ReturnMode	UART_ReturnMode
	UART return mode settings. More...

typedef enum UART_DataMode	UART_DataMode
	UART data mode settings. More...

typedef enum UART_Echo	UART_Echo
	UART echo settings. More...

typedef enum UART_LEN	UART_LEN
	UART data length settings. More...

typedef enum UART_STOP	UART_STOP
	UART stop bit settings. More...

typedef enum UART_PAR	UART_PAR
	UART parity type settings. More...

typedef struct UART_Params	UART_Params
	UART Parameters. More...

typedef void(*	UART_CloseFxn) (UART_Handle handle)
	A function pointer to a driver specific implementation of UART_CloseFxn(). More...

typedef int(*	UART_ControlFxn) (UART_Handle handle, unsigned int cmd, void *arg)
	A function pointer to a driver specific implementation of UART_ControlFxn(). More...

typedef void(*	UART_InitFxn) (UART_Handle handle)
	A function pointer to a driver specific implementation of UART_InitFxn(). More...

typedef UART_Handle(*	UART_OpenFxn) (UART_Handle handle, UART_Params *params)
	A function pointer to a driver specific implementation of UART_OpenFxn(). More...

typedef int(*	UART_ReadFxn) (UART_Handle handle, void *buffer, size_t size)
	A function pointer to a driver specific implementation of UART_ReadFxn(). More...

typedef int(*	UART_ReadPollingFxn) (UART_Handle handle, void *buffer, size_t size)
	A function pointer to a driver specific implementation of UART_ReadPollingFxn(). More...

typedef void(*	UART_ReadCancelFxn) (UART_Handle handle)
	A function pointer to a driver specific implementation of UART_ReadCancelFxn(). More...

typedef int(*	UART_WriteFxn) (UART_Handle handle, const void *buffer, size_t size)
	A function pointer to a driver specific implementation of UART_WriteFxn(). More...

typedef int(*	UART_WritePollingFxn) (UART_Handle handle, const void *buffer, size_t size)
	A function pointer to a driver specific implementation of UART_WritePollingFxn(). More...

typedef void(*	UART_WriteCancelFxn) (UART_Handle handle)
	A function pointer to a driver specific implementation of UART_WriteCancelFxn(). More...

typedef struct UART_FxnTable	UART_FxnTable
	The definition of a UART function table that contains the required set of functions to control a specific UART driver implementation. More...

typedef struct UART_Config	UART_Config
	UART Global configuration. More...

Enumerations
enum	UART_Mode { UART_MODE_BLOCKING, UART_MODE_CALLBACK }
	UART mode settings. More...

enum	UART_ReturnMode { UART_RETURN_FULL, UART_RETURN_NEWLINE }
	UART return mode settings. More...

enum	UART_DataMode { UART_DATA_BINARY = 0, UART_DATA_TEXT = 1 }
	UART data mode settings. More...

enum	UART_Echo { UART_ECHO_OFF = 0, UART_ECHO_ON = 1 }
	UART echo settings. More...

enum	UART_LEN { UART_LEN_5 = 0, UART_LEN_6 = 1, UART_LEN_7 = 2, UART_LEN_8 = 3 }
	UART data length settings. More...

enum	UART_STOP { UART_STOP_ONE = 0, UART_STOP_TWO = 1 }
	UART stop bit settings. More...

enum	UART_PAR { UART_PAR_NONE = 0, UART_PAR_EVEN = 1, UART_PAR_ODD = 2, UART_PAR_ZERO = 3, UART_PAR_ONE = 4 }
	UART parity type settings. More...

Functions
void	UART_close (UART_Handle handle)
	Function to close a UART peripheral specified by the UART handle. More...

int	UART_control (UART_Handle handle, unsigned int cmd, void *arg)
	Function performs implementation specific features on a given UART_Handle. More...

void	UART_init (void)
	Function to initialize the UART module. More...

UART_Handle	UART_open (unsigned int index, UART_Params *params)
	Function to initialize a given UART peripheral. More...

void	UART_Params_init (UART_Params *params)
	Function to initialize the UART_Params struct to its defaults. More...

int	UART_write (UART_Handle handle, const void *buffer, size_t size)
	Function that writes data to a UART with interrupts enabled. More...

int	UART_writePolling (UART_Handle handle, const void *buffer, size_t size)
	Function that writes data to a UART, polling the peripheral to wait until new data can be written. Usage of this API is mutually exclusive with usage of UART_write(). More...

void	UART_writeCancel (UART_Handle handle)
	Function that cancels a UART_write() function call. More...

int	UART_read (UART_Handle handle, void *buffer, size_t size)
	Function that reads data from a UART with interrupt enabled. More...

int	UART_readPolling (UART_Handle handle, void *buffer, size_t size)
	Function that reads data from a UART without interrupts. This API must be used mutually exclusive with UART_read(). More...

void	UART_readCancel (UART_Handle handle)
	Function that cancels a UART_read() function call. More...

Macro Definition Documentation

#define UART_ERROR UART_STATUS_ERROR

#define UART_WAIT_FOREVER (~0)

Wait forever define.

Typedef Documentation

typedef struct UART_Config* UART_Handle

A handle that is returned from a UART_open() call.

typedef void(* UART_Callback) (UART_Handle, void *buf, size_t count)

The definition of a callback function used by the UART driver when used in UART_MODE_CALLBACK The callback can occur in task or HWI context.

Warning: Making UART_read() or UART_write() calls within its own callback routines are STRONGLY discouraged as it will impact Task and System stack size requirements! See the documentation for the specific driver implementations for additional estimated stack requirements.

Parameters

UART_Handle	UART_Handle
buf	Pointer to read/write buffer
count	Number of elements read/written

typedef enum UART_Mode UART_Mode

UART mode settings.

This enum defines the read and write modes for the configured UART.

typedef enum UART_ReturnMode UART_ReturnMode

UART return mode settings.

This enumeration defines the return modes for UART_read() and UART_readPolling(). This mode only functions when in UART_DATA_TEXT mode.

UART_RETURN_FULL unblocks or performs a callback when the read buffer has been filled. UART_RETURN_NEWLINE unblocks or performs a callback whenever a newline character has been received.

UART operation	UART_RETURN_FULL	UART_RETURN_NEWLINE
UART_read	Returns when buffer is full	Returns when buffer is full or newline was read
UART_write	Sends data as is	Sends data with an additional newline at the end

Precondition: UART driver must be used in UART_DATA_TEXT mode.

typedef enum UART_DataMode UART_DataMode

UART data mode settings.

This enumeration defines the data mode for read and write. In UART_DATA_TEXT mode the driver will examine the UART_ReturnMode value.

typedef enum UART_Echo UART_Echo

UART echo settings.

This enumeration defines if the driver will echo data when uses in UART_DATA_TEXT mode. This only applies to data received by the UART.

UART_ECHO_ON will echo back characters it received while in UART_DATA_TEXT mode. UART_ECHO_OFF will not echo back characters it received in UART_DATA_TEXT mode.

Precondition: UART driver must be used in UART_DATA_TEXT mode.

typedef enum UART_LEN UART_LEN

UART data length settings.

This enumeration defines the UART data lengths.

typedef enum UART_STOP UART_STOP

UART stop bit settings.

This enumeration defines the UART stop bits.

typedef enum UART_PAR UART_PAR

UART parity type settings.

This enumeration defines the UART parity types.

typedef struct UART_Params UART_Params

UART Parameters.

UART parameters are used to with the UART_open() call. Default values for these parameters are set using UART_Params_init().

See also: UART_Params_init()

typedef void(* UART_CloseFxn) (UART_Handle handle)

A function pointer to a driver specific implementation of UART_CloseFxn().

typedef int(* UART_ControlFxn) (UART_Handle handle, unsigned int cmd, void *arg)

A function pointer to a driver specific implementation of UART_ControlFxn().

typedef void(* UART_InitFxn) (UART_Handle handle)

A function pointer to a driver specific implementation of UART_InitFxn().

typedef UART_Handle(* UART_OpenFxn) (UART_Handle handle, UART_Params *params)

A function pointer to a driver specific implementation of UART_OpenFxn().

typedef int(* UART_ReadFxn) (UART_Handle handle, void *buffer, size_t size)

A function pointer to a driver specific implementation of UART_ReadFxn().

typedef int(* UART_ReadPollingFxn) (UART_Handle handle, void *buffer, size_t size)

A function pointer to a driver specific implementation of UART_ReadPollingFxn().

typedef void(* UART_ReadCancelFxn) (UART_Handle handle)

A function pointer to a driver specific implementation of UART_ReadCancelFxn().

typedef int(* UART_WriteFxn) (UART_Handle handle, const void *buffer, size_t size)

A function pointer to a driver specific implementation of UART_WriteFxn().

typedef int(* UART_WritePollingFxn) (UART_Handle handle, const void *buffer, size_t size)

A function pointer to a driver specific implementation of UART_WritePollingFxn().

typedef void(* UART_WriteCancelFxn) (UART_Handle handle)

A function pointer to a driver specific implementation of UART_WriteCancelFxn().

typedef struct UART_FxnTable UART_FxnTable

The definition of a UART function table that contains the required set of functions to control a specific UART driver implementation.

typedef struct UART_Config UART_Config

UART Global configuration.

The UART_Config structure contains a set of pointers used to characterize the UART driver implementation.

This structure needs to be defined before calling UART_init() and it must not be changed thereafter.

See also: UART_init()

Enumeration Type Documentation

enum UART_Mode

UART mode settings.

This enum defines the read and write modes for the configured UART.

Enumerator
UART_MODE_BLOCKING	Uses a semaphore to block while data is being sent. Context of the call must be a Task.
UART_MODE_CALLBACK	Non-blocking and will return immediately. When UART_write() or UART_read() has finished, the callback function is called from either the caller's context or from an interrupt context.

enum UART_ReturnMode

UART return mode settings.

This enumeration defines the return modes for UART_read() and UART_readPolling(). This mode only functions when in UART_DATA_TEXT mode.

UART_RETURN_FULL unblocks or performs a callback when the read buffer has been filled. UART_RETURN_NEWLINE unblocks or performs a callback whenever a newline character has been received.

UART operation	UART_RETURN_FULL	UART_RETURN_NEWLINE
UART_read	Returns when buffer is full	Returns when buffer is full or newline was read
UART_write	Sends data as is	Sends data with an additional newline at the end

Precondition: UART driver must be used in UART_DATA_TEXT mode.

Enumerator
UART_RETURN_FULL	Unblock/callback when buffer is full.
UART_RETURN_NEWLINE	Unblock/callback when newline character is received.

enum UART_DataMode

UART data mode settings.

This enumeration defines the data mode for read and write. In UART_DATA_TEXT mode the driver will examine the UART_ReturnMode value.

Enumerator
UART_DATA_BINARY	Data is not processed
UART_DATA_TEXT	Data is processed according to above

enum UART_Echo

UART echo settings.

This enumeration defines if the driver will echo data when uses in UART_DATA_TEXT mode. This only applies to data received by the UART.

UART_ECHO_ON will echo back characters it received while in UART_DATA_TEXT mode. UART_ECHO_OFF will not echo back characters it received in UART_DATA_TEXT mode.

Precondition: UART driver must be used in UART_DATA_TEXT mode.

Enumerator
UART_ECHO_OFF	Data is not echoed
UART_ECHO_ON	Data is echoed

enum UART_LEN

UART data length settings.

This enumeration defines the UART data lengths.

Enumerator
UART_LEN_5	Data length is 5 bits
UART_LEN_6	Data length is 6 bits
UART_LEN_7	Data length is 7 bits
UART_LEN_8	Data length is 8 bits

enum UART_STOP

UART stop bit settings.

This enumeration defines the UART stop bits.

Enumerator
UART_STOP_ONE	One stop bit
UART_STOP_TWO	Two stop bits

enum UART_PAR

UART parity type settings.

This enumeration defines the UART parity types.

Enumerator
UART_PAR_NONE	No parity
UART_PAR_EVEN	Parity bit is even
UART_PAR_ODD	Parity bit is odd
UART_PAR_ZERO	Parity bit is always zero
UART_PAR_ONE	Parity bit is always one

Function Documentation

void UART_close ( UART_Handle handle )

Function to close a UART peripheral specified by the UART handle.

Precondition: UART_open() has been called.; Ongoing asynchronous read or write have been cancelled using UART_readCancel() or UART_writeCancel() respectively.

Parameters

handle A UART_Handle returned from UART_open()

See also: UART_open()

int UART_control	(	UART_Handle	handle,
		unsigned int	cmd,
		void *	arg
	)

Function performs implementation specific features on a given UART_Handle.

Commands for UART_control can originate from UART.h or from implementation specific UART*.h (UARTCC26XX.h, UARTTiva.h, etc.. ) files. While commands from UART.h are API portable across driver implementations, not all implementations may support all these commands. Conversely, commands from driver implementation specific UART*.h files add unique driver capabilities but are not API portable across all UART driver implementations.

Commands supported by UART.h follow a UART_CMD_<cmd> naming convention.
Commands supported by UART*.h follow a UART*_CMD_<cmd> naming convention.
Each control command defines arg differently. The types of arg are documented with each command.

See UART_control command codes for command codes.

See UART_control return status codes for status codes.

Precondition: UART_open() has to be called.

Parameters

handle	A UART handle returned from UART_open()
cmd	UART.h or UART*.h commands.
arg	An optional R/W (read/write) command argument accompanied with cmd

Returns: Implementation specific return codes. Negative values indicate unsuccessful operations.

See also: UART_open()

void UART_init ( void )

Function to initialize the UART module.

Precondition: The UART_config structure must exist and be persistent before this function can be called. This function must also be called before any other UART driver APIs.

UART_Handle UART_open	(	unsigned int	index,
		UART_Params *	params
	)

Function to initialize a given UART peripheral.

Function to initialize a given UART peripheral specified by the particular index value.

Precondition: UART_init() has been called

Parameters

index	Logical peripheral number for the UART indexed into the UART_config table
params	Pointer to a parameter block. If NULL, default parameter values will be used. All the fields in this structure are RO (read-only).

Returns: A UART_Handle upon success. NULL if an error occurs, or if the indexed UART peripheral is already opened.

See also: UART_init(); UART_close()

void UART_Params_init ( UART_Params * params )

Function to initialize the UART_Params struct to its defaults.

Parameters

params An pointer to UART_Params structure for initialization

Defaults values are: readMode = UART_MODE_BLOCKING; writeMode = UART_MODE_BLOCKING; readTimeout = UART_WAIT_FOREVER; writeTimeout = UART_WAIT_FOREVER; readCallback = NULL; writeCallback = NULL; readReturnMode = UART_RETURN_NEWLINE; readDataMode = UART_DATA_TEXT; writeDataMode = UART_DATA_TEXT; readEcho = UART_ECHO_ON; baudRate = 115200; dataLength = UART_LEN_8; stopBits = UART_STOP_ONE; parityType = UART_PAR_NONE;

int UART_write	(	UART_Handle	handle,
		const void *	buffer,
		size_t	size
	)

Function that writes data to a UART with interrupts enabled.

UART_write() writes data from a memory buffer to the UART interface. The source is specified by buffer and the number of bytes to write is given by size.

In UART_MODE_BLOCKING, UART_write() blocks task execution until all the data in buffer has been written.

In UART_MODE_CALLBACK, UART_write() does not block task execution. Instead, a callback function specified by UART_Params::writeCallback is called when the transfer is finished. The callback function can occur in the caller's task context or in a HWI or SWI context, depending on the device implementation. An unfinished asynchronous write operation must always be cancelled using UART_writeCancel() before calling UART_close().

UART_write() is mutually exclusive to UART_writePolling(). For an opened UART peripheral, either UART_write() or UART_writePolling() can be used, but not both.

Warning: Do not call UART_write() from its own callback function when in UART_MODE_CALLBACK.

See also: UART_writePolling()

Parameters

handle	A UART_Handle returned by UART_open()
buffer	A read-only pointer to buffer containing data to be written to the UART
size	The number of bytes in the buffer that should be written to the UART

Returns: Returns the number of bytes that have been written to the UART. If an error occurs, UART_ERROR is returned. In UART_MODE_CALLBACK mode, the return value is always 0.

int UART_writePolling	(	UART_Handle	handle,
		const void *	buffer,
		size_t	size
	)

Function that writes data to a UART, polling the peripheral to wait until new data can be written. Usage of this API is mutually exclusive with usage of UART_write().

This function initiates an operation to write data to a UART controller.

UART_writePolling() will not return until all the data was written to the UART (or to its FIFO if applicable).

See also: UART_write()

Parameters

handle	A UART_Handle returned by UART_open()
buffer	A read-only pointer to the buffer containing the data to be written to the UART
size	The number of bytes in the buffer that should be written to the UART

Returns: Returns the number of bytes that have been written to the UART. If an error occurs, UART_ERROR is returned.

void UART_writeCancel ( UART_Handle handle )

Function that cancels a UART_write() function call.

This function cancels an asynchronous UART_write() operation and is only applicable in UART_MODE_CALLBACK.

Parameters

handle A UART_Handle returned by UART_open()

int UART_read	(	UART_Handle	handle,
		void *	buffer,
		size_t	size
	)

Function that reads data from a UART with interrupt enabled.

UART_read() reads data from a UART controller. The destination is specified by buffer and the number of bytes to read is given by size.

In UART_MODE_BLOCKING, UART_read() blocks task execution until all the data in buffer has been read.

In UART_MODE_CALLBACK, UART_read() does not block task execution. Instead, a callback function specified by UART_Params::readCallback is called when the transfer is finished. The callback function can occur in the caller's context or in HWI or SWI context, depending on the device-specific implementation. An unfinished asynchronous read operation must always be cancelled using UART_readCancel() before calling UART_close().

UART_read() is mutually exclusive to UART_readPolling(). For an opened UART peripheral, either UART_read() or UART_readPolling() can be used, but not both.

Warning: Do not call UART_read() from its own callback function when in UART_MODE_CALLBACK.

See also: UART_readPolling()

Parameters

handle	A UART_Handle returned by UART_open()
buffer	A pointer to an empty buffer to which received data should be written
size	The number of bytes to be written into buffer

Returns: Returns the number of bytes that have been read from the UART, UART_ERROR on an error.

int UART_readPolling	(	UART_Handle	handle,
		void *	buffer,
		size_t	size
	)

Function that reads data from a UART without interrupts. This API must be used mutually exclusive with UART_read().

This function initiates an operation to read data from a UART peripheral.

UART_readPolling will not return until size data was read to the UART.

See also: UART_read()

Parameters

handle	A UART_Handle returned by UART_open()
buffer	A pointer to an empty buffer in which received data should be written to
size	The number of bytes to be written into buffer

Returns: Returns the number of bytes that have been read from the UART, UART_ERROR on an error.

void UART_readCancel ( UART_Handle handle )

Function that cancels a UART_read() function call.

This function cancels an asynchronous UART_read() operation and is only applicable in UART_MODE_CALLBACK.

Parameters

handle A UART_Handle returned by UART_open()

Detailed Description

Operation

Opening the driver

Writing data

Reading data

Implementation

Stack requirements

Instrumentation

Data Structures

Macros

Typedefs

Enumerations

Functions

Macro Definition Documentation

Typedef Documentation

Enumeration Type Documentation

Function Documentation