]>
Commit | Line | Data |
---|---|---|
0a16d4de ML |
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 | ||
68 | All functions can return only two possible error values. SP_ERR_ARG indicates | |
69 | the function was called with invalid arguments. SP_ERR_FAIL indicates that the | |
70 | OS reported a failure. Both these error values are negative. | |
71 | ||
72 | When SP_ERR_FAIL is returned, an error code or string description of the error | |
73 | can be obtained by calling sp_last_error_code() or sp_last_error_message(). The | |
74 | error code or message is that provided by the OS; libserialport does not define | |
75 | any error codes or messages of its own. | |
76 | ||
77 | Functions calls that succeed return SP_OK, which is equal to zero, or where | |
78 | otherwise documented a positive value. | |
79 | ||
80 | The available functions are as follows: | |
81 | ||
82 | Enumeration | |
83 | ----------- | |
84 | ||
85 | char **sp_list_ports(); | |
86 | ||
87 | Lists the serial ports available on the system. The value returned is an array | |
88 | of port names as C strings, terminated by a NULL. It should be freed after use | |
89 | by calling sp_free_port_list(). | |
90 | ||
91 | void sp_free_port_list(char **list); | |
92 | ||
93 | Frees the data structure returned by sp_list_ports(). | |
94 | ||
95 | Opening and closing ports | |
96 | ------------------------- | |
97 | ||
98 | int sp_open(struct sp_port *port, char *portname, int flags); | |
99 | ||
100 | Opens the specified serial port. | |
101 | ||
102 | Parameters: | |
103 | ||
104 | port: Pointer to empty port structure, allocated by caller. | |
105 | portname: Name of port to open. | |
106 | flags: Flags to use when opening the serial port. Possible | |
107 | flags are: SP_MODE_RDWR, SP_MODE_RDONLY, and SP_MODE_NONBLOCK. | |
108 | ||
109 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
110 | if an invalid port or name is passed. | |
111 | ||
112 | int sp_close(struct sp_port *port); | |
113 | ||
114 | Closes the specified serial port. | |
115 | ||
116 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
117 | if an invalid port is passed. | |
118 | ||
119 | Setting port parameters | |
120 | ----------------------- | |
121 | ||
122 | int sp_set_params(struct sp_port *port, int baudrate, | |
123 | int bits, int parity, int stopbits, | |
124 | int flowcontrol, int rts, int dtr); | |
125 | ||
126 | Sets serial parameters for the specified serial port. | |
127 | ||
128 | Parameters: | |
129 | ||
130 | port: Pointer to port structure. | |
131 | baudrate: Baud rate to set. | |
132 | bits: Number of data bits to use. | |
133 | parity: Parity setting to use | |
134 | (SP_PARITY_NONE, SP_PARITY_EVEN or SP_PARITY_ODD) | |
135 | stopbits: Number of stop bits to use (1 or 2). | |
136 | flowcontrol: Flow control setting to use | |
137 | (SP_FLOW_NONE, SP_FLOW_HARDWARE or SP_FLOW_SOFTWARE) | |
138 | ||
139 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
140 | for invalid arguments. | |
141 | ||
142 | Reading, writing and flushing data | |
143 | ---------------------------------- | |
144 | ||
145 | int sp_read(struct sp_port *port, const void *buf, size_t count) | |
146 | ||
147 | Reads a number of bytes from the specified serial port. | |
148 | ||
149 | Parameters: | |
150 | ||
151 | port: Pointer to port structure. | |
152 | buf: Buffer in which to store the bytes read. | |
153 | count: Number of bytes to read. | |
154 | ||
155 | Returns: The number of bytes read, SP_ERR_FAIL on failure, | |
156 | or SP_ERR_ARG for invalid arguments. | |
157 | ||
158 | int sp_write(struct sp_port *port, const void *buf, size_t count) | |
159 | ||
160 | Writes a number of bytes to the specified serial port. | |
161 | ||
162 | Parameters: | |
163 | ||
164 | port: Pointer to port structure. | |
165 | buf: Buffer containing the bytes to write. | |
166 | count: Number of bytes to write. | |
167 | ||
168 | Returns: The number of bytes written, SP_ERR_FAIL on failure, | |
169 | or SP_ERR_ARG for invalid arguments. | |
170 | ||
171 | int sp_flush(struct sp_port *port); | |
172 | ||
173 | Flushes serial port buffers. | |
174 | ||
175 | Returns: SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG | |
176 | if an invalid port is passed. | |
177 | ||
178 | Error handling | |
179 | -------------- | |
180 | ||
181 | int sp_last_error_code(); | |
182 | ||
183 | Gets the error code for a failed operation. | |
184 | ||
185 | In order to obtain the correct result, this function should be called | |
186 | straight after the failure, before executing any other system operations. | |
187 | ||
188 | Returns: The system's numeric code for the error that caused the last | |
189 | operation to fail. | |
190 | ||
191 | char *sp_last_error_message(); | |
192 | ||
193 | Gets the error message for failed operation. | |
194 | ||
195 | In order to obtain the correct result, this function should be called | |
196 | straight after the failure, before executing other system operations. | |
197 | ||
198 | Returns: The system's message for the error that caused the last | |
199 | operation to fail. This string may be allocated by the function, | |
200 | and should be freed after use by calling sp_free_error_message. | |
201 | ||
202 | void sp_free_error_message(char *message); | |
203 | ||
204 | Frees the error message returned by sp_last_error_message(). |