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/>.
22 \mainpage libserialport API
27 libserialport is a minimal library written in C that is intended to take care
28 of the OS-specific details when writing software that uses serial ports.
30 By writing your serial code to use libserialport, you enable it to work
31 transparently on any platform supported by the library.
33 The operations that are supported are:
35 - Port enumeration (obtaining a list of serial ports on the system).
36 - Opening and closing ports.
37 - Setting port parameters (baud rate, parity, etc).
38 - Reading, writing and flushing data.
39 - Obtaining error information.
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 port
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.
52 All functions can return only three possible error values. SP_ERR_ARG indicates
53 the function was called with invalid arguments. SP_ERR_FAIL indicates that the
54 OS reported a failure. SP_ERR_MEM indicates that a memory allocation failed.
55 All of these error values are negative.
57 When SP_ERR_FAIL is returned, an error code or string description of the error
58 can be obtained by calling sp_last_error_code() or sp_last_error_message(). The
59 error code or message is that provided by the OS; libserialport does not define
60 any error codes or messages of its own.
62 Function calls that succeed return SP_OK, which is equal to zero, or where
63 otherwise documented a positive value.
67 #ifndef LIBSERIALPORT_H
68 #define LIBSERIALPORT_H
79 /* Package version macros (e.g. for conditional compilation). */
80 #define SP_PACKAGE_VERSION_MAJOR @SP_PACKAGE_VERSION_MAJOR@
81 #define SP_PACKAGE_VERSION_MINOR @SP_PACKAGE_VERSION_MINOR@
82 #define SP_PACKAGE_VERSION_STRING "@SP_PACKAGE_VERSION@"
84 /* Library/libtool version macros (e.g. for conditional compilation). */
85 #define SP_LIB_VERSION_CURRENT @SP_LIB_VERSION_CURRENT@
86 #define SP_LIB_VERSION_REVISION @SP_LIB_VERSION_REVISION@
87 #define SP_LIB_VERSION_AGE @SP_LIB_VERSION_AGE@
88 #define SP_LIB_VERSION_STRING "@SP_LIB_VERSION@"
92 /** Operation completed successfully. */
94 /** Invalid arguments were passed to the function. */
96 /** A system error occured while executing the operation. */
98 /** A memory allocation failed while executing the operation. */
102 /** Port access modes. */
104 /** Open port for read/write access. */
106 /** Open port for read access only. */
108 /** Open port in non-blocking mode. */
109 SP_MODE_NONBLOCK = 4,
112 /** Parity settings. */
114 SP_PARITY_INVALID = -1,
123 /** RTS pin behaviour. */
130 /** RTS used for flow control. */
131 SP_RTS_FLOW_CONTROL = 2
134 /** CTS pin behaviour. */
139 /** CTS used for flow control. */
140 SP_CTS_FLOW_CONTROL = 1
143 /** DTR pin behaviour. */
150 /** DTR used for flow control. */
151 SP_DTR_FLOW_CONTROL = 2
154 /** DSR pin behaviour. */
159 /** DSR used for flow control. */
160 SP_DSR_FLOW_CONTROL = 1
163 /** XON/XOFF flow control behaviour. */
165 SP_XONXOFF_INVALID = -1,
166 /** XON/XOFF disabled. */
167 SP_XONXOFF_DISABLED = 0,
168 /** XON/XOFF enabled for input only. */
170 /** XON/XOFF enabled for output only. */
172 /** XON/XOFF enabled for input and output. */
176 /** Standard flow control combinations. */
177 enum sp_flowcontrol {
178 /** No flow control. */
179 SP_FLOWCONTROL_NONE = 0,
180 /** Software flow control using XON/XOFF characters. */
181 SP_FLOWCONTROL_XONXOFF = 1,
182 /** Hardware flow control using RTS/CTS signals. */
183 SP_FLOWCONTROL_RTSCTS = 2,
184 /** Hardware flow control using DTR/DSR signals. */
185 SP_FLOWCONTROL_DTRDSR = 3
188 /** A serial port. */
190 /** Name used to open the port */
193 /* OS-specific port handle */
202 /** Configuration for a serial port. */
203 struct sp_port_config {
204 /** Baud rate in bits per second. */
206 /** Number of data bits to use. Valid values are 5 to 8. */
208 /** Parity setting to use. */
209 enum sp_parity parity;
210 /** Number of stop bits to use (1 or 2). */
220 /** XON/XOFF flow control mode. */
221 enum sp_xonxoff xon_xoff;
225 Obtains a pointer to a new sp_port structure representing the named port. The
226 user should allocate a variable of type "struct sp_port *" and pass a pointer
227 to this to receive the result.
229 The result should be freed after use by calling sp_free_port().
231 @return SP_OK on success, SP_ERR_FAIL on failure, SP_ERR_MEM on allocation
232 failure, or SP_ERR_ARG if an invalid pointer is passed. If any error
233 is returned, the variable pointed to by port_ptr will be set to NULL.
234 Otherwise, it will be set to point to the newly allocated port.
236 enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr);
239 Frees a port structure obtained from sp_get_port_by_name() or sp_copy_port().
241 void sp_free_port(struct sp_port *port);
244 Lists the serial ports available on the system. The result obtained is an
245 array of pointers to sp_port structures, terminated by a NULL. The user should
246 allocate a variable of type "struct sp_port **" and pass a pointer to this to
249 The result should be freed after use by calling sp_free_port_list(). If a port
250 from the list is to be used after freeing the list, it must be copied first
251 using sp_copy_port().
253 @return SP_OK on success, SP_ERR_FAIL on failure, SP_ERR_MEM on allocation
254 failure, or SP_ERR_ARG if an invalid pointer is passed. If any error
255 is returned, the variable pointed to by list_ptr will be set to NULL.
256 Otherwise, it will be set to point to the newly allocated array.
258 enum sp_return sp_list_ports(struct sp_port ***list_ptr);
261 Makes a new copy of a sp_port structure. The user should allocate a variable
262 of type "struct sp_port *" and pass a pointer to this to receive the result.
264 The copy should be freed after use by calling sp_free_port().
266 @return SP_OK on success, SP_ERR_MEM on allocation failure, or SP_ERR_ARG
267 if an invalid port or pointer is passed. If any error is returned,
268 the variable pointed to by copy_ptr will be set to NULL. Otherwise,
269 it will be set to point to the newly allocated copy.
271 enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr);
274 Frees a port list obtained from sp_list_ports(). This will also free all
275 the sp_port structures referred to from the list; any that are to be retained
276 must be copied first using sp_copy_port().
278 void sp_free_port_list(struct sp_port **ports);
281 Opens the specified serial port.
283 @param port Pointer to port structure.
284 @param flags Flags to use when opening the serial port.
286 @return SP_OK on success, SP_ERR_FAIL on failure, SP_ERR_MEM on allocation
287 failure, or SP_ERR_ARG if an invalid port is passed.
289 enum sp_return sp_open(struct sp_port *port, enum sp_mode flags);
292 Closes the specified serial port.
294 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
295 if an invalid port is passed.
297 enum sp_return sp_close(struct sp_port *port);
300 Reads bytes from the specified serial port. Note that this function may
301 return after reading less than the specified number of bytes; it is the
302 user's responsibility to iterate as necessary in this case.
304 @param port Pointer to port structure.
305 @param buf Buffer in which to store the bytes read.
306 @param count Maximum number of bytes to read.
308 @return The number of bytes read, SP_ERR_FAIL on failure,
309 or SP_ERR_ARG for invalid arguments.
311 enum sp_return sp_read(struct sp_port *port, void *buf, size_t count);
314 Write bytes to the specified serial port. Note that this function may
315 return after writing less than the specified number of bytes; it is the
316 user's responsibility to iterate as necessary in this case.
318 @param port Pointer to port structure.
319 @param buf Buffer containing the bytes to write.
320 @param count Maximum number of bytes to write.
322 @return The number of bytes written, SP_ERR_FAIL on failure,
323 or SP_ERR_ARG for invalid arguments.
325 enum sp_return sp_write(struct sp_port *port, const void *buf, size_t count);
328 Flushes serial port buffers.
330 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
331 if an invalid port is passed.
333 enum sp_return sp_flush(struct sp_port *port);
336 Gets current configuration of the specified serial port.
338 The user should allocate a struct sp_port_config, then pass a pointer to it
339 as the config parameter. The struct will be populated with the port
342 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
343 for invalid arguments.
345 enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config);
348 Sets all parameters for the specified serial port.
350 The user should populate a struct sp_port_config, then pass a pointer to it
351 as the config parameter.
353 To retain the current value of any setting, set the field to to a
356 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
357 for invalid arguments.
359 enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config);
362 Sets the baud rate for the specified serial port.
364 @param port Pointer to port structure.
365 @param baud Baud rate in bits per second.
367 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
368 for invalid arguments.
370 enum sp_return sp_set_baudrate(struct sp_port *port, int baudrate);
373 Sets the number of data bits for the specified serial port.
375 @param port Pointer to port structure.
376 @param bits Number of data bits to use. Valid values are 5 to 8.
378 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
379 for invalid arguments.
381 enum sp_return sp_set_bits(struct sp_port *port, int bits);
384 Sets the parity for the specified serial port.
386 @param port Pointer to port structure.
387 @param parity Parity setting to use.
389 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
390 for invalid arguments.
392 enum sp_return sp_set_parity(struct sp_port *port, enum sp_parity parity);
395 Sets the number of stop bits for the specified port.
397 @param port Pointer to port structure.
398 @param stopbits Number of stop bits to use (1 or 2).
400 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
401 for invalid arguments.
403 enum sp_return sp_set_stopbits(struct sp_port *port, int stopbits);
406 Sets the flow control type for the specified serial port.
408 This function is a wrapper that sets the RTS, CTS, DTR, DSR and
409 XON/XOFF settings as necessary for the specified flow control
410 type. For more fine-grained control of these settings, use their
411 individual configuration functions or the sp_set_config() function.
413 @param port Pointer to port structure.
414 @param flowcontrol Flow control setting to use.
416 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
417 for invalid arguments.
419 enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol);
422 Sets the RTS pin behaviour for the specified port.
424 @param port Pointer to port structure.
425 @param rts RTS pin mode.
427 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
428 for invalid arguments.
430 enum sp_return sp_set_rts(struct sp_port *port, enum sp_rts rts);
433 Sets the CTS pin behaviour for the specified port.
435 @param port Pointer to port structure.
436 @param cts CTS pin mode.
438 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
439 for invalid arguments.
441 enum sp_return sp_set_cts(struct sp_port *port, enum sp_cts cts);
444 Sets the DTR pin behaviour for the specified port.
446 @param port Pointer to port structure.
447 @param dtr DTR pin mode.
449 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
450 for invalid arguments.
452 enum sp_return sp_set_dtr(struct sp_port *port, enum sp_dtr dtr);
455 Sets the RTS pin behaviour for the specified port.
457 @param port Pointer to port structure.
458 @param dsr DSR pin mode.
460 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
461 for invalid arguments.
463 enum sp_return sp_set_dsr(struct sp_port *port, enum sp_dsr dsr);
466 Configures XON/XOFF flow control for the specified port.
468 @param port Pointer to port structure.
469 @param xon_xoff XON/XOFF flow control mode.
471 @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
472 for invalid arguments.
474 enum sp_return sp_set_xon_xoff(struct sp_port *port, enum sp_xonxoff xon_xoff);
477 Gets the error code for a failed operation.
479 In order to obtain the correct result, this function should be called
480 straight after the failure, before executing any other system operations.
482 @return The system's numeric code for the error that caused the last
485 int sp_last_error_code(void);
488 Gets the error message for a failed operation.
490 In order to obtain the correct result, this function should be called
491 straight after the failure, before executing other system operations.
493 @return The system's message for the error that caused the last
494 operation to fail. This string may be allocated by the function,
495 and should be freed after use by calling sp_free_error_message.
497 char *sp_last_error_message(void);
500 Frees an error message returned by sp_last_error_message().
502 void sp_free_error_message(char *message);
508 #endif /* LIBSERIALPORT_H */