uartat.h File Reference

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Data Structures
struct	_uartat_context

Functions
uartat_context	uartat_init (unsigned int uart, unsigned int baudrate)
uartat_context	uartat_init_tty (const char *uart_tty, unsigned int baudrate)
void	uartat_close (uartat_context dev)
int	uartat_read (const uartat_context dev, char *buffer, size_t len)
int	uartat_write (const uartat_context dev, const char *buffer, size_t len)
upm_result_t	uartat_set_baudrate (const uartat_context dev, unsigned int baudrate)
void	uartat_set_response_wait_time (const uartat_context dev, unsigned int wait_ms)
bool	uartat_data_available (const uartat_context dev, unsigned int millis)
bool	uartat_command_mode (const uartat_context dev, const char *cmd_chars, unsigned int guard_ms)
bool	uartat_in_command_mode (const uartat_context dev)
void	uartat_drain (const uartat_context dev)
int	uartat_command_with_response (const uartat_context dev, const char *cmd, char *resp, size_t resp_len)
void	uartat_command (const uartat_context dev, const char *cmd)
bool	uartat_command_waitfor (const uartat_context dev, const char *cmd, char *resp, size_t resp_len, const char *wait_string, unsigned int millis)
upm_result_t	uartat_set_flow_control (const uartat_context dev, UARTAT_FLOW_CONTROL_T fc)
bool	uartat_find (const uartat_context dev, const char *buffer, const char *str)
void	uartat_filter_cr (const uartat_context dev, bool enable)

Typedefs
typedef struct _uartat_context *	uartat_context

Function Documentation

uartat_context uartat_init	(	unsigned int	uart,
		unsigned int	baudrate
	)

UARTAT Initializer for generic UART operation using a UART index.

Parameters

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

Returns

an initialized device context on success, NULL on error.

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uartat_context uartat_init_tty	(	const char *	uart_tty,
		unsigned int	baudrate
	)

UARTAT Initializer for generic UART operation using a filesystem tty path (eg. /dev/ttyUSB0).

Parameters

uart_tty	character string representing a filesystem path to a serial tty device.
baudrate	Specify the baudrate to use.

Returns

an initialized device context on success, NULL on error.

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void uartat_close

(

uartat_context

dev

)

UARTAT sensor close function

Parameters

dev	Device context

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int uartat_read	(	const uartat_context	dev,
		char *	buffer,
		size_t	len
	)

Read character data from the device.

Parameters

dev	Device context
buffer	The character buffer to read data into.
len	The maximum size of the buffer

Returns

The number of bytes successfully read, or -1 on error

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int uartat_write	(	const uartat_context	dev,
		const char *	buffer,
		size_t	len
	)

Write character data to the device.

Parameters

dev	Device context
buffer	The character buffer containing data to write.
len	The number of bytes to write.

Returns

The number of bytes successfully written, or -1 on error.

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upm_result_t uartat_set_baudrate	(	const uartat_context	dev,
		unsigned int	baudrate
	)

Set the baudrate of the device.

Parameters

dev	Device context
baudrate	The baud rate to set for the device.

Returns

UPM result

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void uartat_set_response_wait_time	(	const uartat_context	dev,
		unsigned int	wait_ms
	)

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

Parameters

dev	Device context
wait_ms	The response delay to set, in milliseconds.

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bool uartat_data_available	(	const uartat_context	dev,
		unsigned int	millis
	)

Determine whether there is data available to be read. This function will wait up to "millis" milliseconds for data to become available.

Parameters

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

Returns

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

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bool uartat_command_mode	(	const uartat_context	dev,
		const char *	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

dev	Device context
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.

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bool uartat_in_command_mode

(

const uartat_context

dev

)

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.

Parameters

dev	Device context

Returns

true if AT command mode was detected, false otherwise.

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void uartat_drain

(

const uartat_context

dev

)

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 uartat_command_with_response(), uartat_command(), and uartat_command_waitfor() prior to writing the requested command to the device.

Parameters

dev	Device context

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int uartat_command_with_response	(	const uartat_context	dev,
		const char *	cmd,
		char *	resp,
		size_t	resp_len
	)

Send an AT command and optionally return a response.

Parameters

dev	Device context
cmd	A character string containing the AT command to send, including the "AT" prefix and a terminating carriage return ("\r").
resp	A pointer to a buffer that will contain the response. If NULL is specified, the response is ignored. The returned string buffer will be 0 terminated like any ordinary C string.
resp_len	The length of the supplied response buffer. If 0, then any response will be ignored. No more than resp_len characters (including the trailing 0 byte) will be returned.

Returns

The number of bytes read, or -1 on error.

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void uartat_command	(	const uartat_context	dev,
		const char *	cmd
	)

Send an AT command and ignore any response. This is a shorthand version of uartat_command_with_response(), and is equivalent to calling uartat_command_with_response(dev, cmd, NULL, 0).

Parameters

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

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bool uartat_command_waitfor	(	const uartat_context	dev,
		const char *	cmd,
		char *	resp,
		size_t	resp_len,
		const char *	wait_string,
		unsigned int	millis
	)

Read characters for up to millis milliseconds, returning as soon as the wait_string is found.

Parameters

dev	Device context
cmd	The command to send
resp	The response character buffer
resp_len	The maximum size of the response buffer
wait_string	The string to search for
millis	The maximum number of milliseconds to look for the wait_string.

Returns

true if the wait_string was found in the response, false otherwise.

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upm_result_t uartat_set_flow_control	(	const uartat_context	dev,
		UARTAT_FLOW_CONTROL_T	fc
	)

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

Parameters

dev	Device context
fc	One of the UARTAT_FLOW_CONTROL_T values.

Returns

the UPM result.

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bool uartat_find	(	const uartat_context	dev,
		const char *	buffer,
		const char *	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

dev	Device context
buffer	The 0 teminated buffer in which to search.
str	The 0 teminated string to search for.

Returns

true if the string was found, false otherwise.

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void uartat_filter_cr	(	const uartat_context	dev,
		bool	enable
	)

Filter out carriage returns (CR) from response buffers if enabled. This operates only on the response buffers returned from uartat_command_with_response(), uartat_command(), and uartat_command_waitfor().

Parameters

dev	Device context
enable	true to filter out CR's, false otherwise

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Typedef Documentation

typedef struct _uartat_context * uartat_context

Device context