NAME¶
owcapi - easy C-language 1-wire interface
SYNOPSIS¶
libowcapi library to link with your program
Initialization¶
ssize_t OW_init( device name or full parameter string )
ssize_t OW_init_args( int argc, char ** args )
The full set of initialization options is extensive. They correspond roughly to
the command line options of
owfs (1) owhttpd (1) and
owftpd
(1)
Get data¶
int OW_present( const char * path )
int OW_get( const char * path, char ** buffer, size_t *
buffer_length )
ssize_t OW_lread( const char * path, unsigned char * buffer, const
size_t size, const off_t offset )
Set data¶
ssize_t OW_put( const char * path, const char * buffer, size_t *
buffer_length )
ssize_t OW_lwrite( const char * path, const unsigned char * buffer,
const size_t size, const off_t offset )
Debug¶
void OW_set_error_level( const char *param )
void OW_set_error_print( const char *param )
Close¶
void OW_finish( void )
FUNCTIONS¶
OW_init¶
OW_init_string offers the full flexibility of the
owfs (1) and
owhttpd (1) command line.
- Arguments
- Can be as simple as jus the device name, a full parameter
specification. One or more device names (includes tcp, serial, usb...) and
command line switches. See owfs (1) for full syntax.
- Returns
- 0 for success. -1 on error and errno will be set.
OW_finish does not need to be called if OW_init fails.
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
OW_init_args¶
OW_init_args offers the full flexibility of the
owfs (1) and
owhttpd (1) command line.
- Arguments
- One or more device names (includes tcp, serial, usb...) and
command line switches. See owfs (1) for full syntax. Unlike
OW_init_string the arguments are in argv/argc format.
- Returns
- 0 for success. -1 on error and errno will be set.
OW_finish does not need to be called if OW_init fails.
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
OW_present¶
OW_present is used to check presence of a 1-wire device.
- Arguments
- path is the path to the directory or file
(property).
- Returns
- 0 on success. -1 on error (and errno is set).
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
OW_get¶
OW_get is used to get directory listings and file contents. The results
are put in a dynamically allocated buffer.
- Arguments
- path is the path to the directory or file
(property). *buffer returns a pointer to a buffer containing the
directory (comma separated) or value. buffer_length returns the
length of the value/string in buffer
- Returns
- number of bytes on success. -1 on error (and errno
is set).
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
- Important note
- buffer is allocated ( with malloc ) by OW_get
but must be freed in your program. See malloc (3) and free
(3)
OW_lread¶
OW_lread is used to read 1-wire memory chips. Think of it as a
combination of
lseek and
read It allows random-access to the
memory, specifying location and length. Unlike
OW_get directories
cannot be obtained and the buffer must be pre-allocated rather than allocated
by the routine.
buffer must be at least
size length.
- Arguments
- path is the path to the file (property).
buffer is the (pre-allocated) memory area where the value will be
placed. size is the length of bytes requested. offset is the
position in file to start reading.
- Returns
- number of bytes on success. -1 on error (and errno
is set).
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
OW_put¶
OW_put is an easy way to write to 1-wire chips.
- Arguments
- path is the path to the file (property).
buffer is the value to be written. buffer_length is the
length of the value buffer. Returns number of bytes on
success. -1 on error (and errno is set).
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
OW_lwrite¶
OW_lwrite is the companion of
OW_lread. It allows writing to
arbitrary positions in 1-wire memory. Think of it as a combination of
lseek and
write. buffer must be at least
size
length.
- Arguments
- path is the path to the file (property).
buffer is the data to be written. size is the length of
bytes to be written. offset is the position in file to start
writing.
- Returns
- number of bytes on success. -1 on error (and errno
is set).
- Sequence
- One of the init functions must be called before
accessing the 1-wire bus. OW_finish is optional.
OW_set_error_level¶
OW_set_error_level sets the debug output to a certain level. 0 is
default, and higher value gives more output.
(0=default, 1=err_connect, 2=err_call, 3=err_data, 4=err_detail, 5=err_debug,
6=err_beyond)
- Arguments
- params is the level. Should be an integer.
- Returns
- None
- Sequence
- One of the init functions must be called before
setting the level, since init defaults to level 0.
OW_set_error_print¶
OW_set_error_print sets where the debug output should be directed.
0=mixed output, 1=syslog, 2=console.
- Arguments
- params is the level. Should be an integer between 0
and 2.
- Returns
- None
- Sequence
- One of the init functions must be called before
setting the level, since init defaults to 0 (mixed output).
OW_finish¶
OW_finish cleans up the
OWFS 1-wire routines, releases devices and
memory.
- Arguments
- None.
- Returns
- None
- Sequence
- OW_finish is optional since cleanup is automatic on
program exit.
DESCRIPTION¶
1-Wire¶
1-wire is a wiring protocol and series of devices designed and
manufactured by Dallas Semiconductor, Inc. The bus is a low-power low-speed
low-connector scheme where the data line can also provide power.
Each device is uniquely and unalterably numbered during manufacture. There are a
wide variety of devices, including memory, sensors (humidity, temperature,
voltage, contact, current), switches, timers and data loggers. More complex
devices (like thermocouple sensors) can be built with these basic devices.
There are also 1-wire devices that have encryption included.
The 1-wire scheme uses a single
bus master and multiple
slaves on
the same wire. The bus master initiates all communication. The slaves can be
individually discovered and addressed using their unique ID.
Bus masters come in a variety of configurations including serial, parallel, i2c,
network or USB adapters.
OWFS design¶
OWFS is a suite of programs that designed to make the 1-wire bus and its
devices easily accessible. The underlying priciple is to create a virtual
filesystem, with the unique ID being the directory, and the individual
properties of the device are represented as simple files that can be read and
written.
Details of the individual slave or master design are hidden behind a consistent
interface. The goal is to provide an easy set of tools for a software designer
to create monitoring or control applications. There are some performance
enhancements in the implementation, including data caching, parallel access to
bus masters, and aggregation of device communication. Still the fundemental
goal has been ease of use, flexibility and correctness rather than speed.
libowcapi¶
libowcapi (1) is an encapsulation of the full
libow library for C
programs.
libowcapi (1) allows a C program to use
OWFS principles
(consistent naming scheme, multiple adapters, devices, and compatibility)
directly from a C program. There are analogous modules for other programming
languages:
- C
- libowcapi
- perl
- owperl
- php
- owphp
- python
- owpython
- tcl
- owtcl
EXAMPLE¶
/* Simple directory listing -- no error checking */
#include <owcapi.h>
unsigned char * buf;
size_t s ;
OW_init("/dev/ttyS0");
OW_set_error_print("2");
OW_set_error_level("6");
OW_get("/",&buf,&s) ;
printf("Directory %s0,buf);
free(buf);
OW_finish() ;
SEE ALSO¶
Programs¶
owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1)
owwrite (1) owpresent (1) owtap (1)
Configuration and testing¶
owfs (5) owtap (1) owmon (1)
Language bindings¶
owtcl (3) owperl (3) owcapi (3)
Clocks¶
DS1427 (3) DS1904(3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417
(3)
DS2401 (3) DS2411 (3) DS1990A (3)
Memory¶
DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3)
DS1996 (3) DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS28E04 (3)
DS28EC20 (3)
Switches¶
DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3)
Temperature¶
DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921
(3) DS1821 (3) DS28EA00 (3) DS28E04 (3)
Humidity¶
DS1922 (3)
Voltage¶
DS2450 (3)
Resistance¶
DS2890 (3)
Multifunction (current, voltage, temperature)¶
DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3)
DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
Counter¶
DS2423 (3)
LCD Screen¶
LCD (3) DS2408 (3)
Crypto¶
DS1977 (3)
Pressure¶
DS2406 (3) -- TAI8570
AVAILABILITY¶
http://www.owfs.org
AUTHOR¶
Paul Alfille (paul.alfille@gmail.com)