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1 | ---------------------------------------------------------------- |
2 | libserialport: cross-platform library for accessing serial ports | |
3 | ---------------------------------------------------------------- | |
4 | ||
5 | libserialport is a minimal library written in C that is intended to take care | |
6 | of the OS-specific details when writing software that uses serial ports. | |
7 | ||
8 | By writing your serial code to use libserialport, you enable it to work | |
9 | transparently on any platform supported by the library. | |
10 | ||
11 | The operations that are supported are: | |
12 | ||
13 | - Port enumeration (obtaining a list of serial ports on the system). | |
14 | - Opening and closing ports. | |
15 | - Setting port parameters (baud rate, parity, etc). | |
16 | - Reading, writing and flushing data. | |
17 | - Obtaining error information. | |
18 | ||
19 | libserialport is an open source project released under the LGPL3+ license. | |
20 | ||
21 | Status | |
22 | ====== | |
23 | ||
24 | The library should build and work on any Windows or Unix-based system. If it | |
25 | does not, please submit a bug. | |
26 | ||
27 | Enumeration is currently only implemented on Windows, Mac OS X and Linux. On | |
28 | other systems enumeration will return no results, but ports can still be opened | |
29 | by name and then used. | |
30 | ||
31 | If you know how to enumerate available ports on another OS, please submit a bug | |
32 | with this information, or better still a patch implementing it. | |
33 | ||
34 | Future | |
35 | ====== | |
36 | ||
37 | Future versions will add additional API calls for obtaining metadata about a | |
38 | port, e.g. for USB devices the USB VID and PID of the underlying device. | |
39 | ||
40 | Dependencies | |
41 | ============ | |
42 | ||
43 | On Linux, libudev is required. On other systems no other libraries are required. | |
44 | ||
45 | The libudev dependency could be eliminated in favour of direct sysfs queries at | |
46 | the cost of some brevity. This is not currently a priority but if you feel like | |
47 | doing this feel free to submit a patch. | |
48 | ||
49 | Building | |
50 | ======== | |
51 | ||
52 | The package uses a GNU style build system and requires a Unix style shell. | |
53 | On Windows it can be built with the MinGW toolchain and MSYS environment. | |
54 | ||
55 | Run "./autogen.sh" to generate the build system, "./configure" to setup, then | |
56 | "make" to build the library and "make install" to install it. | |
57 | ||
58 | API | |
59 | === | |
60 | ||
61 | The API is simple, and designed to be a minimal wrapper around the serial port | |
62 | support in each OS. | |
63 | ||
64 | Most functions take a pointer to a struct sp_port, which represents an open | |
65 | port. This structure should be allocated by the user and is populated by | |
66 | sp_open(). It can be freed safely after sp_close(). | |
67 | ||
e9a2f9c9 | 68 | All functions can return only three possible error values. SP_ERR_ARG indicates |
0a16d4de | 69 | the function was called with invalid arguments. SP_ERR_FAIL indicates that the |
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70 | OS reported a failure. SP_ERR_MEM indicates that a memory allocation failed. |
71 | Aoth these error values are negative. | |
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72 | |
73 | When SP_ERR_FAIL is returned, an error code or string description of the error | |
74 | can be obtained by calling sp_last_error_code() or sp_last_error_message(). The | |
75 | error code or message is that provided by the OS; libserialport does not define | |
76 | any error codes or messages of its own. | |
77 | ||
78 | Functions calls that succeed return SP_OK, which is equal to zero, or where | |
79 | otherwise documented a positive value. | |
80 | ||
81 | The available functions are as follows: | |
82 | ||
83 | Enumeration | |
84 | ----------- | |
85 | ||
86 | char **sp_list_ports(); | |
87 | ||
88 | Lists the serial ports available on the system. The value returned is an array | |
89 | of port names as C strings, terminated by a NULL. It should be freed after use | |
90 | by calling sp_free_port_list(). | |
91 | ||
92 | void sp_free_port_list(char **list); | |
93 | ||
94 | Frees the data structure returned by sp_list_ports(). | |
95 | ||
96 | Opening and closing ports | |
97 | ------------------------- | |
98 | ||
99 | int sp_open(struct sp_port *port, char *portname, int flags); | |
100 | ||
101 | Opens the specified serial port. | |
102 | ||
103 | Parameters: | |
104 | ||
105 | port: Pointer to empty port structure, allocated by caller. | |
106 | portname: Name of port to open. | |
107 | flags: Flags to use when opening the serial port. Possible | |
108 | flags are: SP_MODE_RDWR, SP_MODE_RDONLY, and SP_MODE_NONBLOCK. | |
109 | ||
110 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
111 | if an invalid port or name is passed. | |
112 | ||
113 | int sp_close(struct sp_port *port); | |
114 | ||
115 | Closes the specified serial port. | |
116 | ||
117 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
118 | if an invalid port is passed. | |
119 | ||
120 | Setting port parameters | |
121 | ----------------------- | |
122 | ||
123 | int sp_set_params(struct sp_port *port, int baudrate, | |
124 | int bits, int parity, int stopbits, | |
125 | int flowcontrol, int rts, int dtr); | |
126 | ||
127 | Sets serial parameters for the specified serial port. | |
128 | ||
129 | Parameters: | |
130 | ||
131 | port: Pointer to port structure. | |
132 | baudrate: Baud rate to set. | |
133 | bits: Number of data bits to use. | |
134 | parity: Parity setting to use | |
135 | (SP_PARITY_NONE, SP_PARITY_EVEN or SP_PARITY_ODD) | |
136 | stopbits: Number of stop bits to use (1 or 2). | |
137 | flowcontrol: Flow control setting to use | |
138 | (SP_FLOW_NONE, SP_FLOW_HARDWARE or SP_FLOW_SOFTWARE) | |
139 | ||
140 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
141 | for invalid arguments. | |
142 | ||
143 | Reading, writing and flushing data | |
144 | ---------------------------------- | |
145 | ||
146 | int sp_read(struct sp_port *port, const void *buf, size_t count) | |
147 | ||
148 | Reads a number of bytes from the specified serial port. | |
149 | ||
150 | Parameters: | |
151 | ||
152 | port: Pointer to port structure. | |
153 | buf: Buffer in which to store the bytes read. | |
154 | count: Number of bytes to read. | |
155 | ||
156 | Returns: The number of bytes read, SP_ERR_FAIL on failure, | |
157 | or SP_ERR_ARG for invalid arguments. | |
158 | ||
159 | int sp_write(struct sp_port *port, const void *buf, size_t count) | |
160 | ||
161 | Writes a number of bytes to the specified serial port. | |
162 | ||
163 | Parameters: | |
164 | ||
165 | port: Pointer to port structure. | |
166 | buf: Buffer containing the bytes to write. | |
167 | count: Number of bytes to write. | |
168 | ||
169 | Returns: The number of bytes written, SP_ERR_FAIL on failure, | |
170 | or SP_ERR_ARG for invalid arguments. | |
171 | ||
172 | int sp_flush(struct sp_port *port); | |
173 | ||
174 | Flushes serial port buffers. | |
175 | ||
176 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
177 | if an invalid port is passed. | |
178 | ||
179 | Error handling | |
180 | -------------- | |
181 | ||
182 | int sp_last_error_code(); | |
183 | ||
184 | Gets the error code for a failed operation. | |
185 | ||
186 | In order to obtain the correct result, this function should be called | |
187 | straight after the failure, before executing any other system operations. | |
188 | ||
189 | Returns: The system's numeric code for the error that caused the last | |
190 | operation to fail. | |
191 | ||
192 | char *sp_last_error_message(); | |
193 | ||
194 | Gets the error message for failed operation. | |
195 | ||
196 | In order to obtain the correct result, this function should be called | |
197 | straight after the failure, before executing other system operations. | |
198 | ||
199 | Returns: The system's message for the error that caused the last | |
200 | operation to fail. This string may be allocated by the function, | |
201 | and should be freed after use by calling sp_free_error_message. | |
202 | ||
203 | void sp_free_error_message(char *message); | |
204 | ||
205 | Frees the error message returned by sp_last_error_message(). |