2 * This file is part of the libserialport project.
4 * Copyright (C) 2013 Martin Ling <martin-libserialport@earth.li>
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as
8 * published by the Free Software Foundation, either version 3 of the
9 * License, or (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * @mainpage libserialport API
26 * libserialport is a minimal library written in C that is intended to take
27 * care of the OS-specific details when writing software that uses serial ports.
29 * By writing your serial code to use libserialport, you enable it to work
30 * transparently on any platform supported by the library.
32 * The operations that are supported are:
34 * - @ref Enumeration (obtaining a list of serial ports on the system)
36 * - @ref Configuration (baud rate, parity, etc.)
40 * libserialport is an open source project released under the LGPL3+ license.
45 * The API is simple, and designed to be a minimal wrapper around the serial
46 * port support in each OS.
48 * Most functions take a pointer to a struct sp_port, which represents a serial
49 * port. These structures are always allocated and freed by the library, using
50 * the functions in the @ref Enumeration "Enumeration" section.
52 * All functions can return only four possible error values:
54 * - @ref SP_ERR_ARG means that a function was called with invalid
55 * arguments. This implies a bug in the caller. The arguments passed would
56 * be invalid regardless of the underlying OS or serial device involved.
58 * - @ref SP_ERR_FAIL means that the OS reported a failure. The error code or
59 * message provided by the OS can be obtained by calling sp_last_error_code()
60 * or sp_last_error_message().
62 * - @ref SP_ERR_SUPP indicates that there is no support for the requested
63 * operation in the current OS, driver or device. No error message is
64 * available from the OS in this case. There is either no way to request
65 * the operation in the first place, or libserialport does not know how to
66 * do so in the current version.
68 * - @ref SP_ERR_MEM indicates that a memory allocation failed.
70 * All of these error values are negative.
72 * Function calls that succeed return @ref SP_OK, which is equal to zero,
73 * or where otherwise documented a positive value.
76 #ifndef LIBSERIALPORT_LIBSERIALPORT_H
77 #define LIBSERIALPORT_LIBSERIALPORT_H
88 /* Package version macros (e.g. for conditional compilation). */
89 #define SP_PACKAGE_VERSION_MAJOR @SP_PACKAGE_VERSION_MAJOR@
90 #define SP_PACKAGE_VERSION_MINOR @SP_PACKAGE_VERSION_MINOR@
91 #define SP_PACKAGE_VERSION_MICRO @SP_PACKAGE_VERSION_MICRO@
92 #define SP_PACKAGE_VERSION_STRING "@SP_PACKAGE_VERSION@"
94 /* Library/libtool version macros (e.g. for conditional compilation). */
95 #define SP_LIB_VERSION_CURRENT @SP_LIB_VERSION_CURRENT@
96 #define SP_LIB_VERSION_REVISION @SP_LIB_VERSION_REVISION@
97 #define SP_LIB_VERSION_AGE @SP_LIB_VERSION_AGE@
98 #define SP_LIB_VERSION_STRING "@SP_LIB_VERSION@"
100 /** Return values. */
102 /** Operation completed successfully. */
104 /** Invalid arguments were passed to the function. */
106 /** A system error occured while executing the operation. */
108 /** A memory allocation failed while executing the operation. */
110 /** The requested operation is not supported by this system or device. */
114 /** Port access modes. */
116 /** Open port for read access. */
118 /** Open port for write access. */
120 /** Open port in non-blocking mode. */
121 SP_MODE_NONBLOCK = 4,
124 /** Buffer selection. */
128 /** Output buffer. */
134 /** Parity settings. */
136 /** Special value to indicate setting should be left alone. */
137 SP_PARITY_INVALID = -1,
146 /** RTS pin behaviour. */
148 /** Special value to indicate setting should be left alone. */
154 /** RTS used for flow control. */
155 SP_RTS_FLOW_CONTROL = 2,
158 /** CTS pin behaviour. */
160 /** Special value to indicate setting should be left alone. */
164 /** CTS used for flow control. */
165 SP_CTS_FLOW_CONTROL = 1,
168 /** DTR pin behaviour. */
170 /** Special value to indicate setting should be left alone. */
176 /** DTR used for flow control. */
177 SP_DTR_FLOW_CONTROL = 2,
180 /** DSR pin behaviour. */
182 /** Special value to indicate setting should be left alone. */
186 /** DSR used for flow control. */
187 SP_DSR_FLOW_CONTROL = 1,
190 /** XON/XOFF flow control behaviour. */
192 /** Special value to indicate setting should be left alone. */
193 SP_XONXOFF_INVALID = -1,
194 /** XON/XOFF disabled. */
195 SP_XONXOFF_DISABLED = 0,
196 /** XON/XOFF enabled for input only. */
198 /** XON/XOFF enabled for output only. */
200 /** XON/XOFF enabled for input and output. */
201 SP_XONXOFF_INOUT = 3,
204 /** Standard flow control combinations. */
205 enum sp_flowcontrol {
206 /** No flow control. */
207 SP_FLOWCONTROL_NONE = 0,
208 /** Software flow control using XON/XOFF characters. */
209 SP_FLOWCONTROL_XONXOFF = 1,
210 /** Hardware flow control using RTS/CTS signals. */
211 SP_FLOWCONTROL_RTSCTS = 2,
212 /** Hardware flow control using DTR/DSR signals. */
213 SP_FLOWCONTROL_DTRDSR = 3,
216 /** Input signals. */
218 /** Clear to send. */
220 /** Data set ready. */
222 /** Data carrier detect. */
224 /** Ring indicator. */
228 /** A serial port. */
231 /** Configuration for a serial port. */
232 struct sp_port_config {
233 /** Baud rate in bits per second. */
235 /** Number of data bits to use. Valid values are 5 to 8. */
237 /** Parity setting to use. */
238 enum sp_parity parity;
239 /** Number of stop bits to use (1 or 2). */
249 /** XON/XOFF flow control mode. */
250 enum sp_xonxoff xon_xoff;
254 @defgroup Enumeration Port enumeration
259 * Obtain a pointer to a new sp_port structure representing the named port.
261 * The user should allocate a variable of type "struct sp_port *" and pass a
262 * pointer to this to receive the result.
264 * The result should be freed after use by calling sp_free_port().
266 * If any error is returned, the variable pointed to by port_ptr will be set
267 * to NULL. Otherwise, it will be set to point to the newly allocated port.
269 * @return SP_OK upon success, a negative error code otherwise.
271 enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr);
274 * Get the name of a port.
276 * The name returned is whatever is normally used to refer to a port on the
277 * current operating system; e.g. for Windows it will usually be a "COMn"
278 * device name, and for Unix it will be a device path beginning with "/dev/".
280 * @param port Pointer to port structure.
282 * @return The port name, or NULL if an invalid port is passed. The name
283 * string is part of the port structure and may not be used after the
284 * port structure has been freed.
286 char *sp_get_port_name(const struct sp_port *port);
289 * Free a port structure obtained from sp_get_port_by_name() or sp_copy_port().
291 void sp_free_port(struct sp_port *port);
294 * List the serial ports available on the system.
296 * The result obtained is an array of pointers to sp_port structures,
297 * terminated by a NULL. The user should allocate a variable of type
298 * "struct sp_port **" and pass a pointer to this to receive the result.
300 * The result should be freed after use by calling sp_free_port_list().
301 * If a port from the list is to be used after freeing the list, it must be
302 * copied first using sp_copy_port().
304 * If any error is returned, the variable pointed to by list_ptr will be set
305 * to NULL. Otherwise, it will be set to point to the newly allocated array.
307 * @return SP_OK upon success, a negative error code otherwise.
309 enum sp_return sp_list_ports(struct sp_port ***list_ptr);
312 * Make a new copy of a sp_port structure.
314 * The user should allocate a variable of type "struct sp_port *" and pass a
315 * pointer to this to receive the result.
317 * The copy should be freed after use by calling sp_free_port().
319 * If any error is returned, the variable pointed to by copy_ptr will be set
320 * to NULL. Otherwise, it will be set to point to the newly allocated copy.
322 * @return SP_OK upon success, a negative error code otherwise.
324 enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr);
327 * Free a port list obtained from sp_list_ports().
329 * This will also free all the sp_port structures referred to from the list;
330 * any that are to be retained must be copied first using sp_copy_port().
332 void sp_free_port_list(struct sp_port **ports);
336 * @defgroup Ports Opening and closing ports
341 * Open the specified serial port.
343 * @param port Pointer to port structure.
344 * @param flags Flags to use when opening the serial port.
346 * @return SP_OK upon success, a negative error code otherwise.
348 enum sp_return sp_open(struct sp_port *port, enum sp_mode flags);
351 * Close the specified serial port.
353 * @return SP_OK upon success, a negative error code otherwise.
355 enum sp_return sp_close(struct sp_port *port);
359 * @defgroup Configuration Setting port parameters
364 * Get the current configuration of the specified serial port.
366 * The user should allocate a struct sp_port_config, then pass a pointer to it
367 * as the config parameter. The struct will be populated with the port
370 * Any setting that is in a state not recognised or supported by
371 * libserialport will have its value set to -1 in the struct.
373 * @return SP_OK upon success, a negative error code otherwise.
375 enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config);
378 * Set the configuration for the specified serial port.
380 * The user should populate a struct sp_port_config, then pass a pointer to it
381 * as the config parameter.
383 * To retain the current value of any setting, set that field to -1.
385 * @return SP_OK upon success, a negative error code otherwise.
387 enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config);
390 * Set the baud rate for the specified serial port.
392 * @param port Pointer to port structure.
393 * @param baudrate Baud rate in bits per second.
395 * @return SP_OK upon success, a negative error code otherwise.
397 enum sp_return sp_set_baudrate(struct sp_port *port, int baudrate);
400 * Set the number of data bits for the specified serial port.
402 * @param port Pointer to port structure.
403 * @param bits Number of data bits to use. Valid values are 5 to 8.
405 * @return SP_OK upon success, a negative error code otherwise.
407 enum sp_return sp_set_bits(struct sp_port *port, int bits);
410 * Set the parity for the specified serial port.
412 * @param port Pointer to port structure.
413 * @param parity Parity setting to use.
415 * @return SP_OK upon success, a negative error code otherwise.
417 enum sp_return sp_set_parity(struct sp_port *port, enum sp_parity parity);
420 * Set the number of stop bits for the specified port.
422 * @param port Pointer to port structure.
423 * @param stopbits Number of stop bits to use (1 or 2).
425 * @return SP_OK upon success, a negative error code otherwise.
427 enum sp_return sp_set_stopbits(struct sp_port *port, int stopbits);
430 * Set the flow control type for the specified serial port.
432 * This function is a wrapper that sets the RTS, CTS, DTR, DSR and
433 * XON/XOFF settings as necessary for the specified flow control
434 * type. For more fine-grained control of these settings, use their
435 * individual configuration functions or the sp_set_config() function.
437 * @param port Pointer to port structure.
438 * @param flowcontrol Flow control setting to use.
440 * @return SP_OK upon success, a negative error code otherwise.
442 enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol);
445 * Set the RTS pin behaviour for the specified port.
447 * @param port Pointer to port structure.
448 * @param rts RTS pin mode.
450 * @return SP_OK upon success, a negative error code otherwise.
452 enum sp_return sp_set_rts(struct sp_port *port, enum sp_rts rts);
455 * Set the CTS pin behaviour for the specified port.
457 * @param port Pointer to port structure.
458 * @param cts CTS pin mode.
460 * @return SP_OK upon success, a negative error code otherwise.
462 enum sp_return sp_set_cts(struct sp_port *port, enum sp_cts cts);
465 * Set the DTR pin behaviour for the specified port.
467 * @param port Pointer to port structure.
468 * @param dtr DTR pin mode.
470 * @return SP_OK upon success, a negative error code otherwise.
472 enum sp_return sp_set_dtr(struct sp_port *port, enum sp_dtr dtr);
475 * Set the RTS pin behaviour for the specified port.
477 * @param port Pointer to port structure.
478 * @param dsr DSR pin mode.
480 * @return SP_OK upon success, a negative error code otherwise.
482 enum sp_return sp_set_dsr(struct sp_port *port, enum sp_dsr dsr);
485 * Configure XON/XOFF flow control for the specified port.
487 * @param port Pointer to port structure.
488 * @param xon_xoff XON/XOFF flow control mode.
490 * @return SP_OK upon success, a negative error code otherwise.
492 enum sp_return sp_set_xon_xoff(struct sp_port *port, enum sp_xonxoff xon_xoff);
496 * @defgroup Data Reading, writing, and flushing data
501 * Read bytes from the specified serial port.
503 * Note that this function may return after reading less than the specified
504 * number of bytes; it is the user's responsibility to iterate as necessary
507 * @param port Pointer to port structure.
508 * @param buf Buffer in which to store the bytes read.
509 * @param count Maximum number of bytes to read.
511 * @return The number of bytes read on success, or a negative error code.
513 enum sp_return sp_read(struct sp_port *port, void *buf, size_t count);
516 * Write bytes to the specified serial port.
518 * Note that this function may return after writing less than the specified
519 * number of bytes; it is the user's responsibility to iterate as necessary
522 * @param port Pointer to port structure.
523 * @param buf Buffer containing the bytes to write.
524 * @param count Maximum number of bytes to write.
526 * @return The number of bytes written on success, or a negative error code.
528 enum sp_return sp_write(struct sp_port *port, const void *buf, size_t count);
531 * Flush serial port buffers. Data in the selected buffer(s) is discarded.
533 * @param port Pointer to port structure.
534 * @param buffers Which buffer(s) to flush.
536 * @return SP_OK upon success, a negative error code otherwise.
538 enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers);
541 * Wait for buffered data to be transmitted.
543 * @param port Pointer to port structure.
545 * @return SP_OK upon success, a negative error code otherwise.
547 enum sp_return sp_drain(struct sp_port *port);
551 * @defgroup Signal Port signalling operations
556 * Gets the status of the control signals for the specified port.
558 * The user should allocate a variable of type "enum sp_signal" and pass a
559 * pointer to this variable to receive the result. The result is a bitmask
560 * in which individual signals can be checked by bitwise OR with values of
561 * the sp_signal enum.
563 * @param port Pointer to port structure.
564 * @param signals Pointer to variable to receive result.
566 * @return SP_OK upon success, a negative error code otherwise.
568 enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals);
571 * Put the port transmit line into the break state.
573 * @param port Pointer to port structure.
575 * @return SP_OK upon success, a negative error code otherwise.
577 enum sp_return sp_start_break(struct sp_port *port);
580 * Take the port transmit line out of the break state.
582 * @param port Pointer to port structure.
584 * @return SP_OK upon success, a negative error code otherwise.
586 enum sp_return sp_end_break(struct sp_port *port);
590 * @defgroup Errors Obtaining error information
595 * Get the error code for a failed operation.
597 * In order to obtain the correct result, this function should be called
598 * straight after the failure, before executing any other system operations.
600 * @return The system's numeric code for the error that caused the last
603 int sp_last_error_code(void);
606 * Get the error message for a failed operation.
608 * In order to obtain the correct result, this function should be called
609 * straight after the failure, before executing other system operations.
611 * @return The system's message for the error that caused the last
612 * operation to fail. This string may be allocated by the function,
613 * and should be freed after use by calling sp_free_error_message().
615 char *sp_last_error_message(void);
618 * Free an error message returned by sp_last_error_message().
620 void sp_free_error_message(char *message);
623 * Set the handler function for library debugging messages.
625 * Debugging messages are generated by the library during each operation,
626 * to help in diagnosing problems. The handler will be called for each
627 * message. The handler can be set to NULL to ignore all debug messages.
629 * The handler function should accept a format string and variable length
630 * argument list, in the same manner as e.g. printf().
632 * The default handler is sp_default_debug_handler().
634 void sp_set_debug_handler(void (*handler)(const char *format, ...));
637 * Default handler function for library debugging messages.
639 * This function prints debug messages to the standard error stream if the
640 * environment variable LIBSERIALPORT_DEBUG is set. Otherwise, they are
643 void sp_default_debug_handler(const char *format, ...);