Table of Contents
- Tiny webserver for 1-wire control
[ -c config ] -d serialport | -u | -s [host:]port -p tcp-port
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.
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.
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.
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.
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.
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.
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.)
and BSD enforce a security policy restricting access to hardware ports.
You must have sufficient rights to access the given port or access will
port specifies a serial port, e.g. /dev/ttyS0
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.
- -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_regulartime (DS2480B)
Changes details of bus timing (see DS2480B datasheet). Some devices, like
the Swart LCD cannot work with flextime.
- 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
- Reverse polarity of the DS2480B output transistors? Not needed
for the DS9097U, but required for some other designs.
- --link=port (LINK)
LINK adapter (all versions) in non-emulation mode. Uses an ascii protocol
- --ha7e=port (HA7E)
- Embedded Data Systems HA7E adapter ( and HA7S
) in native ascii mode.
- --ha5=port | --ha5=port:a | --ha5=port:acg (HA5)
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).
| --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
- --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.
(in seconds) for all serial communications. 5 second default. Can be altered
dynamically under /settings/timeout/serial
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.
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
- -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
- --usb_flextime | --usb_regulartime
- Changes the details of 1-wire waveform
timing for certain network configurations.
- Willy Robion’s alternative
- Timeout for USB communications. This has a 5 second
default and can be changed dynamically under /settings/timeout/usb
- 0x1C,0x1D,0x1E,0x1F (DS2482-800 only)
i2c masters have the form /dev/i2c-0, /dev/i2c-1, ...
- -d port | --device=port
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
- --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.
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
Used for testing and development. No actual hardware
is needed. Useful for separating the hardware development from the rest
of the software design.
- LinkHubE network LINK adapter by
- --ha7net=network_address | --ha7net
- HA7Net network 1-wire adapter
with specified tcp address or discovered by udp multicast. By Embedded Data
--timeout_ha7=60 specific timeout for HA7Net communications (60 second default).
- 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 for network bus master communications.
This has a 1 second default and can be changed dynamically under /settings/timeout/network
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.
- is a list of comma-separated 1-wire devices
in the following formats. Note that a valid CRC8 code is created automatically.
- Hexidecimal family codes (the DS18S20, DS2405 and DS1921 in this
- A more complete hexidecimal unique address. Useful
when an actual hardware device should be simulated.
- The 1-wire
device name. (Full ID cannot be speciifed in this format).
address and random values for each read. The device ID is also random (unless
- --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]
- Predictable address and predictable values for each read.
(See the website for the algorhythm).
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.
scale used for data output. Celsius is the default.
- Use the linux kernel w1 virtual
- Timeout for w1 netlink communications. This has
a 10 second default and can be changed dynamically under /settings/timeout/w1
Can also be changed within
the program at /settings/units/temperature_scale
Pressure scale used for data output.
Millibar is the default.
Can also be changed within the program at /settings/units/pressure_scale
Choose the representation of the 1-wire unique
identifiers. OWFS uses these identifiers as unique directory names.
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
Display format for the 1-wire devices. Each device
has a 8byte address, consisting of:
- family code, 1 byte
- ID number,
- 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
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.
the PID -- process ID of owfs into the specified filename. Useful for startup
Whether the program releases the
console and runs in the background after evaluating command line options.
background is the default.
- default mixed destination:
stderr foreground / syslog background
- syslog only
- stderr only
- /dev/null (quiet mode).
- default errors only
- all high level calls
- data summary for each call
- details level
- debugging chaff
--error_level=9 produces a lot of output
Name of an owfs (5)
configuration file with
more command line parameters
See also this man
page and the web site http://www.owfs.org
basic summary of options.
Version of this program and related libraries.
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.
Seconds until a
volatile property expires in the cache. Volatile properties are those (like
temperature) that change on their own.
- 1-wire bus master options
- cache and
communication size and timing
- mountpoint or TCP server settings
- control and debugging options
- Unique ID display format
and temperature scale
Can be changed dynamically at /settings/timeout/volatile
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
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
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:
the expected response from the owserver (1)
is deemed tardy.
Can be changed
dynamically at /settings/timeout/server
Seconds that an
ftp session is kept alive.
Can be changed dynamically at /settings/timeout/ftp
Paul Alfille (email@example.com)
-p 3001 -d /dev/ttyS0
- Web server runs on tcp port 3001, serial
adapter at ttyS0
-p 3001 -s littlehost:4304 --error_level=3
- Web server
on port 3001, from owserver process on host "littlehost", extensive error
-p 3001 -u -u2 -r
- Read-only web server on port 3001, using
two usb adapters.
Table of Contents