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 * Get the operating system handle for a port.
291 * The type of the handle depends on the operating system. On Unix based
292 * systems, the handle is a file descriptor of type "int". On Windows, the
293 * handle is of type "HANDLE". The user should allocate a variable of the
294 * appropriate type and pass a pointer to this to receive the result.
296 * To obtain a valid handle, the port must first be opened by calling
297 * sp_open() using the same port structure.
299 * After the port is closed or the port structure freed, the handle may
300 * no longer be valid.
302 * @warning This feature is provided so that programs may make use of
303 * OS-specific functionality where desired. Obviously this comes
304 * at a cost in portability, however it also cannot be guaranteed
305 * that direct usage of the OS handle will not conflict with the
306 * library's own usage of the port. Be careful.
308 * @return SP_OK upon success, a negative error code otherwise.
310 enum sp_return sp_get_port_handle(const struct sp_port *port, void *result);
313 * Free a port structure obtained from sp_get_port_by_name() or sp_copy_port().
315 void sp_free_port(struct sp_port *port);
318 * List the serial ports available on the system.
320 * The result obtained is an array of pointers to sp_port structures,
321 * terminated by a NULL. The user should allocate a variable of type
322 * "struct sp_port **" and pass a pointer to this to receive the result.
324 * The result should be freed after use by calling sp_free_port_list().
325 * If a port from the list is to be used after freeing the list, it must be
326 * copied first using sp_copy_port().
328 * If any error is returned, the variable pointed to by list_ptr will be set
329 * to NULL. Otherwise, it will be set to point to the newly allocated array.
331 * @return SP_OK upon success, a negative error code otherwise.
333 enum sp_return sp_list_ports(struct sp_port ***list_ptr);
336 * Make a new copy of a sp_port structure.
338 * The user should allocate a variable of type "struct sp_port *" and pass a
339 * pointer to this to receive the result.
341 * The copy should be freed after use by calling sp_free_port().
343 * If any error is returned, the variable pointed to by copy_ptr will be set
344 * to NULL. Otherwise, it will be set to point to the newly allocated copy.
346 * @return SP_OK upon success, a negative error code otherwise.
348 enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr);
351 * Free a port list obtained from sp_list_ports().
353 * This will also free all the sp_port structures referred to from the list;
354 * any that are to be retained must be copied first using sp_copy_port().
356 void sp_free_port_list(struct sp_port **ports);
360 * @defgroup Ports Opening and closing ports
365 * Open the specified serial port.
367 * @param port Pointer to port structure.
368 * @param flags Flags to use when opening the serial port.
370 * @return SP_OK upon success, a negative error code otherwise.
372 enum sp_return sp_open(struct sp_port *port, enum sp_mode flags);
375 * Close the specified serial port.
377 * @return SP_OK upon success, a negative error code otherwise.
379 enum sp_return sp_close(struct sp_port *port);
383 * @defgroup Configuration Setting port parameters
388 * Get the current configuration of the specified serial port.
390 * The user should allocate a struct sp_port_config, then pass a pointer to it
391 * as the config parameter. The struct will be populated with the port
394 * Any setting that is in a state not recognised or supported by
395 * libserialport will have its value set to -1 in the struct.
397 * @return SP_OK upon success, a negative error code otherwise.
399 enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config);
402 * Set the configuration for the specified serial port.
404 * The user should populate a struct sp_port_config, then pass a pointer to it
405 * as the config parameter.
407 * To retain the current value of any setting, set that field to -1.
409 * @return SP_OK upon success, a negative error code otherwise.
411 enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config);
414 * Set the baud rate for the specified serial port.
416 * @param port Pointer to port structure.
417 * @param baudrate Baud rate in bits per second.
419 * @return SP_OK upon success, a negative error code otherwise.
421 enum sp_return sp_set_baudrate(struct sp_port *port, int baudrate);
424 * Set the number of data bits for the specified serial port.
426 * @param port Pointer to port structure.
427 * @param bits Number of data bits to use. Valid values are 5 to 8.
429 * @return SP_OK upon success, a negative error code otherwise.
431 enum sp_return sp_set_bits(struct sp_port *port, int bits);
434 * Set the parity for the specified serial port.
436 * @param port Pointer to port structure.
437 * @param parity Parity setting to use.
439 * @return SP_OK upon success, a negative error code otherwise.
441 enum sp_return sp_set_parity(struct sp_port *port, enum sp_parity parity);
444 * Set the number of stop bits for the specified port.
446 * @param port Pointer to port structure.
447 * @param stopbits Number of stop bits to use (1 or 2).
449 * @return SP_OK upon success, a negative error code otherwise.
451 enum sp_return sp_set_stopbits(struct sp_port *port, int stopbits);
454 * Set the flow control type for the specified serial port.
456 * This function is a wrapper that sets the RTS, CTS, DTR, DSR and
457 * XON/XOFF settings as necessary for the specified flow control
458 * type. For more fine-grained control of these settings, use their
459 * individual configuration functions or the sp_set_config() function.
461 * @param port Pointer to port structure.
462 * @param flowcontrol Flow control setting to use.
464 * @return SP_OK upon success, a negative error code otherwise.
466 enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol);
469 * Set the RTS pin behaviour for the specified port.
471 * @param port Pointer to port structure.
472 * @param rts RTS pin mode.
474 * @return SP_OK upon success, a negative error code otherwise.
476 enum sp_return sp_set_rts(struct sp_port *port, enum sp_rts rts);
479 * Set the CTS pin behaviour for the specified port.
481 * @param port Pointer to port structure.
482 * @param cts CTS pin mode.
484 * @return SP_OK upon success, a negative error code otherwise.
486 enum sp_return sp_set_cts(struct sp_port *port, enum sp_cts cts);
489 * Set the DTR pin behaviour for the specified port.
491 * @param port Pointer to port structure.
492 * @param dtr DTR pin mode.
494 * @return SP_OK upon success, a negative error code otherwise.
496 enum sp_return sp_set_dtr(struct sp_port *port, enum sp_dtr dtr);
499 * Set the RTS pin behaviour for the specified port.
501 * @param port Pointer to port structure.
502 * @param dsr DSR pin mode.
504 * @return SP_OK upon success, a negative error code otherwise.
506 enum sp_return sp_set_dsr(struct sp_port *port, enum sp_dsr dsr);
509 * Configure XON/XOFF flow control for the specified port.
511 * @param port Pointer to port structure.
512 * @param xon_xoff XON/XOFF flow control mode.
514 * @return SP_OK upon success, a negative error code otherwise.
516 enum sp_return sp_set_xon_xoff(struct sp_port *port, enum sp_xonxoff xon_xoff);
520 * @defgroup Data Reading, writing, and flushing data
525 * Read bytes from the specified serial port.
527 * Note that this function may return after reading less than the specified
528 * number of bytes; it is the user's responsibility to iterate as necessary
531 * @param port Pointer to port structure.
532 * @param buf Buffer in which to store the bytes read.
533 * @param count Maximum number of bytes to read.
535 * @return The number of bytes read on success, or a negative error code.
537 enum sp_return sp_read(struct sp_port *port, void *buf, size_t count);
540 * Write bytes to the specified serial port.
542 * Note that this function may return after writing less than the specified
543 * number of bytes; it is the user's responsibility to iterate as necessary
546 * @param port Pointer to port structure.
547 * @param buf Buffer containing the bytes to write.
548 * @param count Maximum number of bytes to write.
550 * @return The number of bytes written on success, or a negative error code.
552 enum sp_return sp_write(struct sp_port *port, const void *buf, size_t count);
555 * Flush serial port buffers. Data in the selected buffer(s) is discarded.
557 * @param port Pointer to port structure.
558 * @param buffers Which buffer(s) to flush.
560 * @return SP_OK upon success, a negative error code otherwise.
562 enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers);
565 * Wait for buffered data to be transmitted.
567 * @param port Pointer to port structure.
569 * @return SP_OK upon success, a negative error code otherwise.
571 enum sp_return sp_drain(struct sp_port *port);
575 * @defgroup Signal Port signalling operations
580 * Gets the status of the control signals for the specified port.
582 * The user should allocate a variable of type "enum sp_signal" and pass a
583 * pointer to this variable to receive the result. The result is a bitmask
584 * in which individual signals can be checked by bitwise OR with values of
585 * the sp_signal enum.
587 * @param port Pointer to port structure.
588 * @param signals Pointer to variable to receive result.
590 * @return SP_OK upon success, a negative error code otherwise.
592 enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals);
595 * Put the port transmit line into the break state.
597 * @param port Pointer to port structure.
599 * @return SP_OK upon success, a negative error code otherwise.
601 enum sp_return sp_start_break(struct sp_port *port);
604 * Take the port transmit line out of the break state.
606 * @param port Pointer to port structure.
608 * @return SP_OK upon success, a negative error code otherwise.
610 enum sp_return sp_end_break(struct sp_port *port);
614 * @defgroup Errors Obtaining error information
619 * Get the error code for a failed operation.
621 * In order to obtain the correct result, this function should be called
622 * straight after the failure, before executing any other system operations.
624 * @return The system's numeric code for the error that caused the last
627 int sp_last_error_code(void);
630 * Get the error message for a failed operation.
632 * In order to obtain the correct result, this function should be called
633 * straight after the failure, before executing other system operations.
635 * @return The system's message for the error that caused the last
636 * operation to fail. This string may be allocated by the function,
637 * and should be freed after use by calling sp_free_error_message().
639 char *sp_last_error_message(void);
642 * Free an error message returned by sp_last_error_message().
644 void sp_free_error_message(char *message);
647 * Set the handler function for library debugging messages.
649 * Debugging messages are generated by the library during each operation,
650 * to help in diagnosing problems. The handler will be called for each
651 * message. The handler can be set to NULL to ignore all debug messages.
653 * The handler function should accept a format string and variable length
654 * argument list, in the same manner as e.g. printf().
656 * The default handler is sp_default_debug_handler().
658 void sp_set_debug_handler(void (*handler)(const char *format, ...));
661 * Default handler function for library debugging messages.
663 * This function prints debug messages to the standard error stream if the
664 * environment variable LIBSERIALPORT_DEBUG is set. Otherwise, they are
667 void sp_default_debug_handler(const char *format, ...);