--- name: "owcapi" section: "1" platform: "linux" package: "libow-dev" version: "3.2p3+dfsg1-2+deb10u1" release: "Debian 10 (Buster)" platforms: ["linux"] url: "https://new.carta.tech/owcapi" --- # owcapi(1) easy C-language 1-wire interface ## 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 principle 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 fundamental 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 \\ 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)](/DS1904/3.md) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)** ### ID **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)