API for a Generic AT command based UART device. More...

Detailed Description

ID: uartat
Name: Generic AT Command Based UART Device
Category: other
Connection: uart

This is a generic UART device driver for accessing UART based devices that utilize an "AT" command set. Typically these devices are Radios, Modems, and similar devices that are configured and controlled by emitting "AT" commands.

Public Member Functions
	UARTAT (unsigned int uart, unsigned int baudrate)

	UARTAT (std::string uart_path, unsigned int baudrate)

	~UARTAT ()

std::string	readStr (size_t size)

int	writeStr (std::string buffer)

void	setBaudrate (unsigned int baudrate)

void	setResponseWaitTime (unsigned int wait_time)

bool	dataAvailable (unsigned int millis)

bool	commandMode (const std::string cmd_chars, unsigned int guard_ms)

bool	inCommandMode ()

void	drain ()

std::string	commandWithResponse (const std::string cmd, size_t resp_len)

std::string	commandWaitFor (const std::string cmd, size_t resp_len, const std::string waitString, unsigned int millis)

void	command (const std::string cmd)

std::string	stringCR2LF (std::string str)

void	setFlowControl (UARTAT_FLOW_CONTROL_T fc)

bool	find (const std::string buffer, const std::string str)

void	filterCR (bool enable)

Protected Attributes
uartat_context	m_uartat

Constructor & Destructor Documentation

UARTAT	(	unsigned int	uart,
		unsigned int	baudrate
	)

UARTAT object constructor for a UART specified by MRAA number.

Parameters

uart	Specify which uart to use.
baudrate	Specify the baudrate to use.

UARTAT	(	std::string	uart_path,
		unsigned int	baudrate
	)

UARTAT object constructor for a UART specified by PATH (ex: /dev/ttyUSB0)

Parameters

uart_path	Specify path of UART device.
baudrate	Specify the baudrate to use.

~UARTAT ( )

UARTAT object destructor

Here is the call graph for this function:

Member Function Documentation

std::string readStr ( size_t size )

Read character data from the device.

Parameters

size	The maximum number of characters to read.

Returns: string containing the data read.

Here is the call graph for this function:

int writeStr ( std::string buffer )

Write character data to the device.

Parameters

buffer The string containing the data to write.

Returns: The number of bytes written.

Here is the call graph for this function:

void setBaudrate ( unsigned int baudrate )

Set the baudrate of the device.

Parameters

baudrate The baud rate to set for the device.

Here is the call graph for this function:

void setResponseWaitTime ( unsigned int wait_time )

Set the default time, in milliseconds, to wait for data to arrive after sending a command.

Parameters

wait_ms The response delay to set, in milliseconds.

Here is the call graph for this function:

bool dataAvailable ( unsigned int millis )

Determine whether there is data available to be read. In the case of a UART, this function will wait up to "millis" milliseconds for data to become available. In the case of an I2C device, the millis argument is ignored and the function will return immediately, indicating whether data is available.

Parameters

millis The number of milliseconds to wait for data to become available.

Returns: true if data is available to be read, false otherwise.

Here is the call graph for this function:

bool commandMode	(	const std::string	cmd_chars,
		unsigned int	guard_ms
	)

Place the device in AT command mode. Many devices operate in a transparent mode and an AT command mode. Command mode is required to issue AT based commands. When in transparent mode, the device will usually listen for a special sequence of characters and delays, indicating that AT command mode should be entered.

On most devices, the sequence is: <wait 1 second>+++<wait 1 second>

For most devices, the wait time is 1 second (1000 ms) and the character sequence is "+++". These options can often be configured on the device.

This function will wait millis milliseconds, write the command characters (typically "+++"), then wait millis milliseconds again. At this time a read will be attempted, looking for the "OK" response indicating command mode was successfully entered.

Parameters

cmd_chars	The character sequence to write, typically "+++".
guard_ms	The number of milliseconds to delay before and after the cmd_chars are written.

Returns: true if AT command mode ("OK" detected) was successfully entered, false otherwise.

Here is the call graph for this function:

bool inCommandMode ( )

Check to see if the device is in command mode. This is accomplished by sending an "AT\r" command and seeing if "OK" or "0" is returned.

Returns: true if AT command mode was detected, false otherwise.

Here is the call graph for this function:

void drain ( )

Read and throw away any data currently available to be read. This is useful to avoid reading data that might have been the result of a previous command interfering with data you currently want to read. This function is automatically called by commandWithResponse(), command(), and commandWaitfor() prior to writing the requested command to the device.

Here is the call graph for this function:

string commandWithResponse	(	const std::string	cmd,
		size_t	resp_len
	)

Send an AT command and optionally return a response.

Parameters

cmd	A character string containing the AT command to send, including the "AT" prefix and a terminating carriage return ("\r").
resp_len	The maximum number of characters to read from the device.

Returns: The device response string, if any.

Here is the call graph for this function:

string commandWaitFor	(	const std::string	cmd,
		size_t	resp_len,
		const std::string	waitString,
		unsigned int	millis
	)

Send an AT command and return a response, while waiting for a specific string. If the string isn't found the returned string will be empty. If the string is found, the function will return immediately.

Parameters

cmd	A character string containing the AT command to send, including the "AT" prefix and a terminating carriage return ("\r").
resp_len	The maximum number of characters to read from the device.
wait_string	The string to look for. If found, the response will be returned immediately regardless of the timeout setting.
millis	The maximum number of milliseconds to wait for the string.

Returns: A string containing the response if the search string was found, otherwise and empty string is returned.

Here is the call graph for this function:

void command ( const std::string cmd )

Send an AT command and ignore any response.

Parameters

cmd	The AT command to send, including the "AT" prefix and a terminating carriage return ("\r").

Here is the call graph for this function:

string stringCR2LF ( std::string str )

This is a convenience method that converts each CR () in a string to a LF (
) and returns it. This is useful for outputting the response to an AT command for instance, which is often CR terminated.

Parameters

str	The string to convert

Returns: The converted string

void setFlowControl ( UARTAT_FLOW_CONTROL_T fc )

Set a flow control method for the UART. By default, during initialization, flow control is disabled.

Parameters

fc	One of the UARTAT_FLOW_CONTROL_T values.

Here is the call graph for this function:

bool find	(	const std::string	buffer,
		const std::string	str
	)

Look for a string in a buffer. This is a utility function that can be used to indicate if a given string is present in a supplied buffer. The search is case sensitive.

Parameters

buffer	The string buffer in which to search.
str	The string to search for.

Returns: true if the string was found, false otherwise.

Here is the call graph for this function:

void filterCR ( bool enable )

Filter out carriage returns (CR) from response buffers if enabled. This operates only on the response buffers returned from commandWithResponse(), command(), and commandWaitfor().

Parameters

enable true to filter out CR's, false otherwise

Here is the call graph for this function:

Collaboration diagram for UARTAT:

[legend]

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

/iotdk/jenkins/workspace/upm-doc-stable/src/uartat/uartat.hpp
/iotdk/jenkins/workspace/upm-doc-stable/src/uartat/uartat.cxx

Detailed Description

Public Member Functions

Protected Attributes

Constructor & Destructor Documentation

Member Function Documentation