OWCAPI(1) One-Wire File System OWCAPI(1)NAME
owcapi - easy C-language 1-wire interface
SYNOPSISlibowcapi 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 * buf‐
fer_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 speci‐
fication. 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 com‐
mand 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 combina‐
tion of lseek and read It allows random-access to the memory, specify‐
ing location and length. Unlike OW_get directories cannot be obtained
and the buffer must be pre-allocated rather than allocated by the rou‐
tine. 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 mem‐
ory.
Arguments
None.
Returns
None
Sequence
OW_finish is optional since cleanup is automatic on program
exit.
DESCRIPTIONlibowcapi
libowcapi (1) is an encapsulation of the full libow library for C pro‐
grams.
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 ALSOAVAILABILITY
http://www.owfs.org
AUTHOR
Paul Alfille (paul.alfille@gmail.com)
OWFS Manpage 2004 OWCAPI(1)
