Uart Class Reference

Detailed Description

This file defines the UART interface for libmraa

    // If you have a valid platform configuration use numbers to represent uart
    // device. If not use raw mode where std::string is taken as a constructor
    // parameter
    mraa::Uart* uart;
    try {
        uart = new mraa::Uart(UART_PORT);
    } catch (std::exception& e) {
        std::cerr << e.what() << ", likely invalid platform config" << std::endl;
    }

    try {
        uart = new mraa::Uart(dev_path);
    } catch (std::exception& e) {
        std::cerr << "Error while setting up raw UART, do you have a uart?" << std::endl;
        std::terminate();
    }

    if (uart->setBaudRate(115200) != mraa::SUCCESS) {
        std::cerr << "Error setting parity on UART" << std::endl;
    }

    if (uart->setMode(8, mraa::UART_PARITY_NONE, 1) != mraa::SUCCESS) {
        std::cerr << "Error setting parity on UART" << std::endl;
    }

    if (uart->setFlowcontrol(false, false) != mraa::SUCCESS) {
        std::cerr << "Error setting flow control UART" << std::endl;
    }

    while (flag) {
        /* send data through uart */
        uart->writeStr("Hello Mraa!");

        sleep(1);
    }

Public Member Functions
	Uart (int uart)
	Uart (std::string path)
	Uart (void *uart_context)
	~Uart ()
std::string	getDevicePath ()
int	read (char *data, int length)
int	write (const char *data, int length)
std::string	readStr (int length)
int	writeStr (std::string data)
bool	dataAvailable (unsigned int millis=0)
Result	flush ()
Result	sendBreak (int duration)
Result	setBaudRate (unsigned int baud)
Result	setMode (int bytesize, UartParity parity, int stopbits)
Result	setFlowcontrol (bool xonxoff, bool rtscts)
Result	setTimeout (int read, int write, int interchar)
Result	setNonBlocking (bool nonblock)

Constructor & Destructor Documentation

Uart ( int  uart )

inline

Uart Constructor, takes a pin number which will map directly to the linux uart number, this 'enables' the uart, nothing more

Parameters

uart	the index of the uart set to use

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Uart ( std::string  path )

inline

Uart Constructor, takes a string to the path of the serial interface that is needed.

Parameters

path	the index of the uart set to use

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Uart ( void *  uart_context )

inline

Uart Constructor, takes a pointer to the UART context and initialises the UART class

Parameters

uart_context

void * to a UART context

~Uart ( )

inline

Uart destructor

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Member Function Documentation

std::string getDevicePath ( )

inline

Get string with tty device path within Linux For example. Could point to "/dev/ttyS0"

Returns

char pointer of device path

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int read ( char *  data, int  length  )

inline

Read bytes from the device into char* buffer

Parameters

data	buffer pointer
length	maximum size of buffer

Returns

numbers of bytes read

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int write ( const char *  data, int  length  )

inline

Write bytes in char* buffer to a device

Parameters

data	buffer pointer
length	maximum size of buffer

Returns

the number of bytes written, or -1 if an error occurred

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std::string readStr ( int  length )

inline

Read bytes from the device into a String object

Parameters

length

to read

Exceptions

std::bad_alloc

If there is no space left for read.

Returns

string of data

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int writeStr ( std::string  data )

inline

Write bytes in String object to a device

Parameters

data	string to write

Returns

the number of bytes written, or -1 if an error occurred

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bool dataAvailable ( unsigned int  millis = 0 )

inline

Check to see if data is available on the device for reading

Parameters

millis

number of milliseconds to wait, or 0 to return immediately

Returns

true if there is data available to read, false otherwise

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Result flush ( )

inline

Flush the outbound data. Blocks until complete.

Returns

Result of operation

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Result sendBreak ( int  duration )

inline

Send a break to the device. Blocks until complete.

Parameters

duration

When 0, send a break lasting at least 250 milliseconds, and not more than 500 milliseconds. When non zero, the break duration is implementation specific.

Returns

Result of operation

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Result setBaudRate ( unsigned int  baud )

inline

Set the baudrate. Takes an int and will attempt to decide what baudrate is to be used on the UART hardware.

Parameters

baud	unsigned int of baudrate i.e. 9600

Returns

Result of operation

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Result setMode ( int  bytesize, UartParity  parity, int  stopbits  )

inline

Set the transfer mode For example setting the mode to 8N1 would be "dev.setMode(8,UART_PARITY_NONE , 1)"

Parameters

bytesize	data bits
parity	Parity bit setting
stopbits	stop bits

Returns

Result of operation

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Result setFlowcontrol ( bool  xonxoff, bool  rtscts  )

inline

Set the flowcontrol

Parameters

xonxoff	XON/XOFF Software flow control.
rtscts	RTS/CTS out of band hardware flow control

Returns

Result of operation

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Result setTimeout ( int  read, int  write, int  interchar  )

inline

Set the timeout for read and write operations <= 0 will disable that timeout

Parameters

read	read timeout
write	write timeout
interchar	inbetween char timeout

Returns

Result of operation

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Result setNonBlocking ( bool  nonblock )

inline

Set the blocking state for write operations

Parameters

nonblock

new nonblocking state

Returns

Result of operation

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The documentation for this class was generated from the following file:

• api/mraa/uart.hpp