Provided by: owhttpd_2.8p15-1ubuntu4_amd64 
NAME
owhttpd - Tiny webserver for 1-wire control
SYNOPSIS
owhttpd [ -c config ] -d serialport | -u | -s [host:]port -p tcp-port
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.
owhttpd
owhttpd (1) is a small webserver that shows the Dallas/Maxim 1-Wire bus attached to a serial port. The
main view shows the devices found, You can then navigate to individual devices, and view/alter their
properties.
owhttpd (1) uses the same naming convention as owfs (1) , where the URL corresponds to the filename.
The web server is a modified version of chttpd by Greg Olszewski. It serves no files from the disk, only
virtual files from the 1-wire bus. Security should therefore be good. Only the 1-wire bus is at risk.
SPECIFIC OPTIONS
-p portnum
Sets the tcp port the web server runs on. Access with the URL http://servernameoripaddress:portnum
If no port is specified, an ephemeral port is selected by the operating system. Use zeroconf (Bonjour) to
discover the assigned port.
Device Options (1-wire Bus Master)
These options specify the device (bus master) connecting the computer to the 1-wire bus. The 1-wire
slaves are connected to the 1-wire bus, and the bus master connects to a port on the computer and
controls the 1-wire bus. The bus master is either an actual physical device, the kernel w1 module, or an
owserver (1).
At least one device option is required. There is no default. More than one device can be listed, and all
will be used. (A logical union unless you explore the /bus.n/ directories.)
Linux and BSD enforce a security policy restricting access to hardware ports. You must have sufficient
rights to access the given port or access will silently fail.
* Serial devices
port specifies a serial port, e.g. /dev/ttyS0
-d port | --device=port (DS2480B)
DS2480B-based bus master (like the DS9097U or the LINK in emulation mode). If the adapter doesn't
respond, a passive type (DS9907E or diode/resistor) circuit will be assumed.
--serial_flextime | --serial_regulartime (DS2480B)
Changes details of bus timing (see DS2480B datasheet). Some devices, like the Swart LCD cannot
work with flextime.
--baud=1200|9600|19200|38400|57600|115200 (DS2480B,LINK,HA5)
Sets the initial serial port communication speed for all bus masters. Not all serial devices
support all speeds. You can change the individual bus master speed for the LINK and DS2880B in the
interface/settings directory. The HA5 speed is set in hardware, so the command line buad rate
should match that rate.
Usually the default settings (9600 for LINK and DS2480B ) and 115200 for the HA5 are sane and
shouldn't be changed.
--straight_polarity | --reverse_polarity (DS2480B)
Reverse polarity of the DS2480B output transistors? Not needed for the DS9097U, but required for
some other designs.
--link=port (LINK)
iButtonLink LINK adapter (all versions) in non-emulation mode. Uses an ascii protocol over serial.
--ha7e=port (HA7E)
Embedded Data Systems HA7E adapter ( and HA7S ) in native ascii mode.
--ha5=port | --ha5=port:a | --ha5=port:acg (HA5)
Embedded Data Systems HA5 mutidrop adapter in native ascii mode. Up to 26 adapters can share the
same port, each with an assigned letter. If no letter specified, the program will scan for the
first response (which may be slow).
--checksum | --no_checksum (HA5)
Turn on (default) or off the checksum feature of the HA5 communication.
--passive=port | --ha2=port | --ha3=port | --ha4b=port (Passive)
Passive 1-wire adapters. Powered off the serial port and using passive electrical components
(resitors and diodes).
--8bit | --6bit (Passive)
Synthesize the 1-wire waveforme using a 6-bit (default) serial word, or 8-bit word. Not all UART
devices support 6 bit operation.
--timeout_serial=5
Timeout (in seconds) for all serial communications. 5 second default. Can be altered dynamically
under /settings/timeout/serial
* USB devices
The only supported true USB bus masters are based on the DS2490 chip. The most common is the DS9490R
which has an included 1-wire ID slave with family code 81.
There are also bus masters based on the serial chip with a USB to serial conversion built in. These are
supported by the serial bus master protocol.
-u | --usb
DS2490 based bus master (like the DS9490R).
-u2 | --usb=2
Use the second USB bus master. (The order isn't predicatble, however, since the operating system
does not conssitently order USB devices).
-uall | --usb=ALL
Use all the USB devices.
--usb_flextime | --usb_regulartime
Changes the details of 1-wire waveform timing for certain network configurations.
--altusb
Willy Robion's alternative USB timing.
--timeout_usb=5
Timeout for USB communications. This has a 5 second default and can be changed dynamically under
/settings/timeout/usb
* I2C devices
I2C is 2 wire protocol used for chip-to-chip communication. The bus masters: DS2482-100, DS2482-101 and
DS2482-800 can specify (via pin voltages) a subset of addresses on the i2c bus. Those choices are
i2c_address
0,1,2,3
0x18,0x19,0x1A,0x1B
4,5,6,7
0x1C,0x1D,0x1E,0x1F (DS2482-800 only)
port for i2c masters have the form /dev/i2c-0, /dev/i2c-1, ...
-d port | --device=port
This simple form only permits a specific port and the first available i2c_address
--i2c=port | --i2c=port:i2c_address | --i2c=port:ALL
Specific i2c port and the i2c_address is either the first, specific, or all or them. The
i2c_address is 0,1,2,...
--i2c | --i2c=: | --i2c=ALL:ALL
Search the available i2c buses for either the first, the first, or every i2c adapter.
The DS2482-800 masters 8 1-wire buses and so will generate 8 /bus.n entries.
* Network devices
These bus masters communicate via the tcp/ip network protocol and so can be located anywhere on the
network. The network_address is of the form tcp_address:port
E.g. 192.168.0.1:3000 or localhost:3000
--link=network_address
LinkHubE network LINK adapter by iButtonLink
--ha7net=network_address | --ha7net
HA7Net network 1-wire adapter with specified tcp address or discovered by udp multicast. By
Embedded Data Systems
--timeout_ha7=60 specific timeout for HA7Net communications (60 second default).
--etherweather=network_address
Etherweather adapter
-s network_address | --server=network_address
Location of an owserver (1) program that talks to the 1-wire bus. The default port is 4304.
--timeout_network=5
Timeout for network bus master communications. This has a 1 second default and can be changed
dynamically under /settings/timeout/network
* Simulated devices
Used for testing and development. No actual hardware is needed. Useful for separating the hardware
development from the rest of the software design.
devices
is a list of comma-separated 1-wire devices in the following formats. Note that a valid CRC8 code
is created automatically.
10,05,21
Hexidecimal family codes (the DS18S20, DS2405 and DS1921 in this example).
10.12AB23431211
A more complete hexidecimal unique address. Useful when an actual hardware device should be
simulated.
DS2408,DS2489
The 1-wire device name. (Full ID cannot be speciifed in this format).
--fake=devices
Random address and random values for each read. The device ID is also random (unless specified).
--temperature_low=12 --temperature_high=44
Specify the temperature limits for the fake adapter simulation. These should be in the same
temperature scale that is specified in the command line. It is possible to change the limits
dynamically for each adapter under
/bus.x/interface/settings/simulated/[temperature_low|temperature_high]
--tester=devices
Predictable address and predictable values for each read. (See the website for the algorhythm).
* w1 kernel module
This a linux-specific option for using the operating system's access to bus masters. Root access is
required and the implementation was still in progress as of owfs v2.7p12 and linux 2.6.30.
Bus masters are recognized and added dynamically. Details of the physical bus master are not accessible,
bu they include USB, i2c and a number of GPIO designs on embedded boards.
Access is restrict to superuser due to the netlink broadcast protocol employed by w1. Multitasking must
be configured (threads) on the compilation.
--w1 Use the linux kernel w1 virtual bus master.
--timeout_w1=10
Timeout for w1 netlink communications. This has a 10 second default and can be changed dynamically
under /settings/timeout/w1
TEMPERATURE SCALE OPTIONS
-C --Celsius
-F --Fahrenheit
-K --Kelvin
-R --Rankine
Temperature scale used for data output. Celsius is the default.
Can also be changed within the program at /settings/units/temperature_scale
PRESSURE SCALE OPTIONS
--mbar (default)
--atm
--mmHg
--inHg
--psi
--Pa
Pressure scale used for data output. Millibar is the default.
Can also be changed within the program at /settings/units/pressure_scale
FORMAT OPTIONS
Choose the representation of the 1-wire unique identifiers. OWFS uses these identifiers as unique
directory names.
Although several display formats are selectable, all must be in family-id-crc8 form, unlike some other
programs and the labelling on iButtons, which are crc8-id-family form.
-f --format="f[.]i[[.]c]"
Display format for the 1-wire devices. Each device has a 8byte address, consisting of:
f family code, 1 byte
i ID number, 6 bytes
c CRC checksum, 1 byte
Possible formats are f.i (default, 01.A1B2C3D4E5F6), fi fic f.ic f.i.c and fi.c
All formats are accepted as input, but the output will be in the specified format.
The address elements can be retrieved from a device entry in owfs by the family, id and crc8 properties,
and as a whole with address. The reversed id and address can be retrieved as r_id and r_address.
JOB CONTROL OPTIONS
-r --readonly
-w --write
Do we allow writing to the 1-wire bus (writing memory, setting switches, limits, PIOs)? The write option
is available for symmetry, it's the default.
-P --pid-file filename
Places the PID -- process ID of owfs into the specified filename. Useful for startup scripts control.
--background | --foreground
Whether the program releases the console and runs in the background after evaluating command line
options. background is the default.
--error_print=0|1|2|3
=0 default mixed destination: stderr foreground / syslog background
=1 syslog only
=2 stderr only
=3 /dev/null (quiet mode).
--error_level=0..9
=0 default errors only
=1 connections/disconnections
=2 all high level calls
=3 data summary for each call
=4 details level
>4 debugging chaff
--error_level=9 produces a lot of output
CONFIGURATION FILE
-c file | --configuration file
Name of an owfs (5) configuration file with more command line parameters
HELP OPTIONS
See also this man page and the web site http://www.owfs.org
-h --help=[device|cache|program|job|temperature]
Shows basic summary of options.
device 1-wire bus master options
cache cache and communication size and timing
program
mountpoint or TCP server settings
job control and debugging options
temperature
Unique ID display format and temperature scale
-V --version
Version of this program and related libraries.
TIME OPTIONS
Timeouts for the bus masters were previously listed in Device options. Timeouts for the cache affect the
time that data stays in memory. Default values are shown.
--timeout_volatile=15
Seconds until a volatile property expires in the cache. Volatile properties are those (like temperature)
that change on their own.
Can be changed dynamically at /settings/timeout/volatile
--timeout_stable=300
Seconds until a stable property expires in the cache. Stable properties are those that shouldn't change
unless explicitly changed. Memory contents for example.
Can be changed dynamically at /settings/timeout/stable
--timeout_directory=60
Seconds until a directory listing expires in the cache. Directory lists are the 1-wire devices found on
the bus.
Can be changed dynamically at /settings/timeout/directory
--timeout_presence=120
Seconds until the presence and bus location of a 1-wire device expires in the cache.
Can be changed dynamically at /settings/timeout/presence
There are also timeouts for specific program responses:
--timeout_server=5
Seconds until the expected response from the owserver (1) is deemed tardy.
Can be changed dynamically at /settings/timeout/server
--timeout_ftp=900
Seconds that an ftp session is kept alive.
Can be changed dynamically at /settings/timeout/ftp
EXAMPLE
owhttpd -p 3001 -d /dev/ttyS0
Web server runs on tcp port 3001, serial adapter at ttyS0
owhttpd -p 3001 -s littlehost:4304 --error_level=3
Web server on port 3001, from owserver process on host "littlehost", extensive error messages.
owhttpd -p 3001 -u -u2 -r
Read-only web server on port 3001, using two usb adapters.
AVAILABILITY
http://www.owfs.org
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)
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
AUTHOR
Paul Alfille (paul.alfille@gmail.com)