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.)
37 * - @ref Signals (modem control lines, breaks, etc.)
41 * libserialport is an open source project released under the LGPL3+ license.
46 * The API is simple, and designed to be a minimal wrapper around the serial
47 * port support in each OS.
49 * Most functions take a pointer to a struct sp_port, which represents a serial
50 * port. These structures are always allocated and freed by the library, using
51 * the functions in the @ref Enumeration "Enumeration" section.
53 * Most functions have return type @ref sp_return and can return only four
54 * possible error values:
56 * - @ref SP_ERR_ARG means that a function was called with invalid
57 * arguments. This implies a bug in the caller. The arguments passed would
58 * be invalid regardless of the underlying OS or serial device involved.
60 * - @ref SP_ERR_FAIL means that the OS reported a failure. The error code or
61 * message provided by the OS can be obtained by calling sp_last_error_code()
62 * or sp_last_error_message().
64 * - @ref SP_ERR_SUPP indicates that there is no support for the requested
65 * operation in the current OS, driver or device. No error message is
66 * available from the OS in this case. There is either no way to request
67 * the operation in the first place, or libserialport does not know how to
68 * do so in the current version.
70 * - @ref SP_ERR_MEM indicates that a memory allocation failed.
72 * All of these error values are negative.
74 * Calls that succeed return @ref SP_OK, which is equal to zero. Some functions
75 * declared @ref sp_return can also return a positive value for a successful
76 * numeric result, e.g. sp_read() and sp_write().
79 #ifndef LIBSERIALPORT_LIBSERIALPORT_H
80 #define LIBSERIALPORT_LIBSERIALPORT_H
91 /* Package version macros (e.g. for conditional compilation). */
92 #define SP_PACKAGE_VERSION_MAJOR @SP_PACKAGE_VERSION_MAJOR@
93 #define SP_PACKAGE_VERSION_MINOR @SP_PACKAGE_VERSION_MINOR@
94 #define SP_PACKAGE_VERSION_MICRO @SP_PACKAGE_VERSION_MICRO@
95 #define SP_PACKAGE_VERSION_STRING "@SP_PACKAGE_VERSION@"
97 /* Library/libtool version macros (e.g. for conditional compilation). */
98 #define SP_LIB_VERSION_CURRENT @SP_LIB_VERSION_CURRENT@
99 #define SP_LIB_VERSION_REVISION @SP_LIB_VERSION_REVISION@
100 #define SP_LIB_VERSION_AGE @SP_LIB_VERSION_AGE@
101 #define SP_LIB_VERSION_STRING "@SP_LIB_VERSION@"
103 /** Return values. */
105 /** Operation completed successfully. */
107 /** Invalid arguments were passed to the function. */
109 /** A system error occured while executing the operation. */
111 /** A memory allocation failed while executing the operation. */
113 /** The requested operation is not supported by this system or device. */
117 /** Port access modes. */
119 /** Open port for read access. */
121 /** Open port for write access. */
123 /** Open port in non-blocking mode. */
124 SP_MODE_NONBLOCK = 4,
127 /** Buffer selection. */
131 /** Output buffer. */
137 /** Parity settings. */
139 /** Special value to indicate setting should be left alone. */
140 SP_PARITY_INVALID = -1,
149 /** RTS pin behaviour. */
151 /** Special value to indicate setting should be left alone. */
157 /** RTS used for flow control. */
158 SP_RTS_FLOW_CONTROL = 2,
161 /** CTS pin behaviour. */
163 /** Special value to indicate setting should be left alone. */
167 /** CTS used for flow control. */
168 SP_CTS_FLOW_CONTROL = 1,
171 /** DTR pin behaviour. */
173 /** Special value to indicate setting should be left alone. */
179 /** DTR used for flow control. */
180 SP_DTR_FLOW_CONTROL = 2,
183 /** DSR pin behaviour. */
185 /** Special value to indicate setting should be left alone. */
189 /** DSR used for flow control. */
190 SP_DSR_FLOW_CONTROL = 1,
193 /** XON/XOFF flow control behaviour. */
195 /** Special value to indicate setting should be left alone. */
196 SP_XONXOFF_INVALID = -1,
197 /** XON/XOFF disabled. */
198 SP_XONXOFF_DISABLED = 0,
199 /** XON/XOFF enabled for input only. */
201 /** XON/XOFF enabled for output only. */
203 /** XON/XOFF enabled for input and output. */
204 SP_XONXOFF_INOUT = 3,
207 /** Standard flow control combinations. */
208 enum sp_flowcontrol {
209 /** No flow control. */
210 SP_FLOWCONTROL_NONE = 0,
211 /** Software flow control using XON/XOFF characters. */
212 SP_FLOWCONTROL_XONXOFF = 1,
213 /** Hardware flow control using RTS/CTS signals. */
214 SP_FLOWCONTROL_RTSCTS = 2,
215 /** Hardware flow control using DTR/DSR signals. */
216 SP_FLOWCONTROL_DTRDSR = 3,
219 /** Input signals. */
221 /** Clear to send. */
223 /** Data set ready. */
225 /** Data carrier detect. */
227 /** Ring indicator. */
231 /** A serial port. */
234 /** Configuration for a serial port. */
235 struct sp_port_config {
236 /** Baud rate in bits per second. */
238 /** Number of data bits to use. Valid values are 5 to 8. */
240 /** Parity setting to use. */
241 enum sp_parity parity;
242 /** Number of stop bits to use (1 or 2). */
252 /** XON/XOFF flow control mode. */
253 enum sp_xonxoff xon_xoff;
257 @defgroup Enumeration Port enumeration
262 * Obtain a pointer to a new sp_port structure representing the named port.
264 * The user should allocate a variable of type "struct sp_port *" and pass a
265 * pointer to this to receive the result.
267 * The result should be freed after use by calling sp_free_port().
269 * If any error is returned, the variable pointed to by port_ptr will be set
270 * to NULL. Otherwise, it will be set to point to the newly allocated port.
272 * @return SP_OK upon success, a negative error code otherwise.
274 enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr);
277 * Free a port structure obtained from sp_get_port_by_name() or sp_copy_port().
279 void sp_free_port(struct sp_port *port);
282 * List the serial ports available on the system.
284 * The result obtained is an array of pointers to sp_port structures,
285 * terminated by a NULL. The user should allocate a variable of type
286 * "struct sp_port **" and pass a pointer to this to receive the result.
288 * The result should be freed after use by calling sp_free_port_list().
289 * If a port from the list is to be used after freeing the list, it must be
290 * copied first using sp_copy_port().
292 * If any error is returned, the variable pointed to by list_ptr will be set
293 * to NULL. Otherwise, it will be set to point to the newly allocated array.
295 * @return SP_OK upon success, a negative error code otherwise.
297 enum sp_return sp_list_ports(struct sp_port ***list_ptr);
300 * Make a new copy of a sp_port structure.
302 * The user should allocate a variable of type "struct sp_port *" and pass a
303 * pointer to this to receive the result.
305 * The copy should be freed after use by calling sp_free_port().
307 * If any error is returned, the variable pointed to by copy_ptr will be set
308 * to NULL. Otherwise, it will be set to point to the newly allocated copy.
310 * @return SP_OK upon success, a negative error code otherwise.
312 enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr);
315 * Free a port list obtained from sp_list_ports().
317 * This will also free all the sp_port structures referred to from the list;
318 * any that are to be retained must be copied first using sp_copy_port().
320 void sp_free_port_list(struct sp_port **ports);
324 * @defgroup Ports Opening, closing and querying ports
329 * Open the specified serial port.
331 * @param port Pointer to port structure.
332 * @param flags Flags to use when opening the serial port.
334 * @return SP_OK upon success, a negative error code otherwise.
336 enum sp_return sp_open(struct sp_port *port, enum sp_mode flags);
339 * Close the specified serial port.
341 * @return SP_OK upon success, a negative error code otherwise.
343 enum sp_return sp_close(struct sp_port *port);
346 * Get the name of a port.
348 * The name returned is whatever is normally used to refer to a port on the
349 * current operating system; e.g. for Windows it will usually be a "COMn"
350 * device name, and for Unix it will be a device path beginning with "/dev/".
352 * @param port Pointer to port structure.
354 * @return The port name, or NULL if an invalid port is passed. The name
355 * string is part of the port structure and may not be used after the
356 * port structure has been freed.
358 char *sp_get_port_name(const struct sp_port *port);
361 * Get the operating system handle for a port.
363 * The type of the handle depends on the operating system. On Unix based
364 * systems, the handle is a file descriptor of type "int". On Windows, the
365 * handle is of type "HANDLE". The user should allocate a variable of the
366 * appropriate type and pass a pointer to this to receive the result.
368 * To obtain a valid handle, the port must first be opened by calling
369 * sp_open() using the same port structure.
371 * After the port is closed or the port structure freed, the handle may
372 * no longer be valid.
374 * @warning This feature is provided so that programs may make use of
375 * OS-specific functionality where desired. Doing so obviously
376 * comes at a cost in portability. It also cannot be guaranteed
377 * that direct usage of the OS handle will not conflict with the
378 * library's own usage of the port. Be careful.
380 * @return SP_OK upon success, a negative error code otherwise.
382 enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr);
386 * @defgroup Configuration Setting port parameters
391 * Get the current configuration of the specified serial port.
393 * The user should allocate a struct sp_port_config, then pass a pointer to it
394 * as the config parameter. The struct will be populated with the port
397 * Any setting that is in a state not recognised or supported by
398 * libserialport will have its value set to -1 in the struct.
400 * @return SP_OK upon success, a negative error code otherwise.
402 enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config);
405 * Set the configuration for the specified serial port.
407 * The user should populate a struct sp_port_config, then pass a pointer to it
408 * as the config parameter.
410 * To retain the current value of any setting, set that field to -1.
412 * @return SP_OK upon success, a negative error code otherwise.
414 enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config);
417 * Set the baud rate for the specified serial port.
419 * @param port Pointer to port structure.
420 * @param baudrate Baud rate in bits per second.
422 * @return SP_OK upon success, a negative error code otherwise.
424 enum sp_return sp_set_baudrate(struct sp_port *port, int baudrate);
427 * Set the number of data bits for the specified serial port.
429 * @param port Pointer to port structure.
430 * @param bits Number of data bits to use. Valid values are 5 to 8.
432 * @return SP_OK upon success, a negative error code otherwise.
434 enum sp_return sp_set_bits(struct sp_port *port, int bits);
437 * Set the parity for the specified serial port.
439 * @param port Pointer to port structure.
440 * @param parity Parity setting to use.
442 * @return SP_OK upon success, a negative error code otherwise.
444 enum sp_return sp_set_parity(struct sp_port *port, enum sp_parity parity);
447 * Set the number of stop bits for the specified port.
449 * @param port Pointer to port structure.
450 * @param stopbits Number of stop bits to use (1 or 2).
452 * @return SP_OK upon success, a negative error code otherwise.
454 enum sp_return sp_set_stopbits(struct sp_port *port, int stopbits);
457 * Set the flow control type for the specified serial port.
459 * This function is a wrapper that sets the RTS, CTS, DTR, DSR and
460 * XON/XOFF settings as necessary for the specified flow control
461 * type. For more fine-grained control of these settings, use their
462 * individual configuration functions or the sp_set_config() function.
464 * @param port Pointer to port structure.
465 * @param flowcontrol Flow control setting to use.
467 * @return SP_OK upon success, a negative error code otherwise.
469 enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol);
472 * Set the RTS pin behaviour for the specified port.
474 * @param port Pointer to port structure.
475 * @param rts RTS pin mode.
477 * @return SP_OK upon success, a negative error code otherwise.
479 enum sp_return sp_set_rts(struct sp_port *port, enum sp_rts rts);
482 * Set the CTS pin behaviour for the specified port.
484 * @param port Pointer to port structure.
485 * @param cts CTS pin mode.
487 * @return SP_OK upon success, a negative error code otherwise.
489 enum sp_return sp_set_cts(struct sp_port *port, enum sp_cts cts);
492 * Set the DTR pin behaviour for the specified port.
494 * @param port Pointer to port structure.
495 * @param dtr DTR pin mode.
497 * @return SP_OK upon success, a negative error code otherwise.
499 enum sp_return sp_set_dtr(struct sp_port *port, enum sp_dtr dtr);
502 * Set the RTS pin behaviour for the specified port.
504 * @param port Pointer to port structure.
505 * @param dsr DSR pin mode.
507 * @return SP_OK upon success, a negative error code otherwise.
509 enum sp_return sp_set_dsr(struct sp_port *port, enum sp_dsr dsr);
512 * Configure XON/XOFF flow control for the specified port.
514 * @param port Pointer to port structure.
515 * @param xon_xoff XON/XOFF flow control mode.
517 * @return SP_OK upon success, a negative error code otherwise.
519 enum sp_return sp_set_xon_xoff(struct sp_port *port, enum sp_xonxoff xon_xoff);
523 * @defgroup Data Reading, writing, and flushing data
528 * Read bytes from the specified serial port.
530 * Note that this function may return after reading less than the specified
531 * number of bytes; it is the user's responsibility to iterate as necessary
534 * @param port Pointer to port structure.
535 * @param buf Buffer in which to store the bytes read.
536 * @param count Maximum number of bytes to read.
538 * @return The number of bytes read on success, or a negative error code.
540 enum sp_return sp_read(struct sp_port *port, void *buf, size_t count);
543 * Write bytes to the specified serial port.
545 * Note that this function may return after writing less than the specified
546 * number of bytes; it is the user's responsibility to iterate as necessary
549 * @param port Pointer to port structure.
550 * @param buf Buffer containing the bytes to write.
551 * @param count Maximum number of bytes to write.
553 * @return The number of bytes written on success, or a negative error code.
555 enum sp_return sp_write(struct sp_port *port, const void *buf, size_t count);
558 * Flush serial port buffers. Data in the selected buffer(s) is discarded.
560 * @param port Pointer to port structure.
561 * @param buffers Which buffer(s) to flush.
563 * @return SP_OK upon success, a negative error code otherwise.
565 enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers);
568 * Wait for buffered data to be transmitted.
570 * @param port Pointer to port structure.
572 * @return SP_OK upon success, a negative error code otherwise.
574 enum sp_return sp_drain(struct sp_port *port);
578 * @defgroup Signals Port signalling operations
583 * Gets the status of the control signals for the specified port.
585 * The user should allocate a variable of type "enum sp_signal" and pass a
586 * pointer to this variable to receive the result. The result is a bitmask
587 * in which individual signals can be checked by bitwise OR with values of
588 * the sp_signal enum.
590 * @param port Pointer to port structure.
591 * @param signals Pointer to variable to receive result.
593 * @return SP_OK upon success, a negative error code otherwise.
595 enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals);
598 * Put the port transmit line into the break state.
600 * @param port Pointer to port structure.
602 * @return SP_OK upon success, a negative error code otherwise.
604 enum sp_return sp_start_break(struct sp_port *port);
607 * Take the port transmit line out of the break state.
609 * @param port Pointer to port structure.
611 * @return SP_OK upon success, a negative error code otherwise.
613 enum sp_return sp_end_break(struct sp_port *port);
617 * @defgroup Errors Obtaining error information
622 * Get the error code for a failed operation.
624 * In order to obtain the correct result, this function should be called
625 * straight after the failure, before executing any other system operations.
627 * @return The system's numeric code for the error that caused the last
630 int sp_last_error_code(void);
633 * Get the error message for a failed operation.
635 * In order to obtain the correct result, this function should be called
636 * straight after the failure, before executing other system operations.
638 * @return The system's message for the error that caused the last
639 * operation to fail. This string may be allocated by the function,
640 * and should be freed after use by calling sp_free_error_message().
642 char *sp_last_error_message(void);
645 * Free an error message returned by sp_last_error_message().
647 void sp_free_error_message(char *message);
650 * Set the handler function for library debugging messages.
652 * Debugging messages are generated by the library during each operation,
653 * to help in diagnosing problems. The handler will be called for each
654 * message. The handler can be set to NULL to ignore all debug messages.
656 * The handler function should accept a format string and variable length
657 * argument list, in the same manner as e.g. printf().
659 * The default handler is sp_default_debug_handler().
661 void sp_set_debug_handler(void (*handler)(const char *format, ...));
664 * Default handler function for library debugging messages.
666 * This function prints debug messages to the standard error stream if the
667 * environment variable LIBSERIALPORT_DEBUG is set. Otherwise, they are
670 void sp_default_debug_handler(const char *format, ...);