| DS1921-Thermochron(3) | One-Wire File System | DS1921-Thermochron(3) |
DS1921 - Thermochron temperature logging iButton.
Temperature logging iButton.
21 [.]XXXXXXXXXXXX[XX][/[
about/[measuring| resolution| samples| templow| temphigh| version] |
clock/[date| running| udate] |
histotgram/[counts[0-62|ALL]| gap| temperature[counts[0-62|ALL]] |
log[date[0-2047|ALL]| elements| temperature[0-2047|ALL]|
udate[0-2047|ALL]] |
memory |
mission/[date| delay| easystart| frequency| rollover| running| samples|
sampling| udate] |
overtemp/[date[0-11|ALL]| elements| end[0-11|ALL]| count[0-11|ALL]|
temperature[0-11|ALL]| udate[0-11|ALL]] |
pages/page.[0-15|ALL] |
temperature |
undertemp/[date[0-11|ALL]| elements|end[0-11|ALL]| count[0-11|ALL]|
temperature[0-11|ALL]| udate[0-11|ALL]] | address | crc8 |
id | locator | r_address | r_id |
r_locator | type ]]
21
read-only, yes-no
Is this DS1921 currently measuring a temperature?
read-only, floating point
What is the resolution of the temperature measurments (in the current
temperature scale).
read-only, unsigned integer
How many total temperature measurements has this DS1921 performed?
read-only, floating point
Highest temperature this DS1921 can measure (in the current temperature
scale).
read-only, floating point
Lowest temperature this DS1921 can measure (in the current temperature
scale).
read-only, ascii
Specific version of this DS1921.
read-write, ascii
26 character date representation of the internal time stored in this
DS1921. Increments once per second while clock/running
Setting date to a null string will put the current system time.
Accepted date formats are:
Sat[urday] March 12 12:23:59 2001
Apr[il] 4 9:34:56 2002
3/23/04 23:34:57
current locale setting (your system's format)
read-write, yes-no
Whether the internal clock is running. This can be explicitly set, and is
automatically started by setting clock/date or clock/udate or
by starting a mission with mission/easystart or
mission/frequency
The main reason to stop the clock is to conserve the internal battery. The clock cannot be stopped during a mission, and the clock is essential for a mission.
read-write, unsigned integer
A numeric representation of clock/date
The number of seconds in UNIX time (since Jan 1, 1970).
read-only, unsigned integer
The number of samples in the current mission whose temperature fell within the
histogram/temperature to histogram/temperature+histogram/gap
range.
read-only, unsigned integer
The number of bins in the histogram. Always 63.
read-only, floating point
The size of the histogram bin. Depends on the Thermochron version (
about/version ) and is usually 4 times about/resolution
Given in the current temperatature scale.
read-only, floating point
Lower limit of the temperature range for the corresponding histogram bin. In
the current temperature scale.
read-only, ascii
Date that the corresponding log/temperature was taken, in ascii format.
(See clock/date for more on the format). The number of valid entries
is actually log/elements since the log may not be full.
mission/samples gives the total number of samples that have been taken but there is only room in the log for 2048 entries. Once the log is full, mission/rollover determines the Thermochron's behavior.
If mission/rollover is false(0), the log will hold the first 2048 samples and log/date.0 will always be the same as mission/date
If mission/rollover is true (1) then the log will hold the last 2048 samples and the entries will be shifted down with each new sample.
Note the OWFS code "untwists" the rollover behavior. The data will always be a linear array of earliest to latest.
ALL is the all data elements comma separated.
read-only, unsigned integer
Number of valid entries in the log. OWFS offers the full 2048 values in
the log memory, but not that many samples may yet have been taken.
log/elements will range from 0 to 2048 and always be less than or
equal to mission/samples
read-write, floating point
The temperature readings (in the current temperature scale) that correspond to
the log/date sample. See log/date for details on the indexing
scheme and rollover behavior.
read-write, unsigned integer
A numeric representation of log/date
The number of seconds in UNIX time (since Jan 1, 1970).
read-write, binary
User available storage space. 512 bytes. Can also be accessed as 16 pages of
32 bytes with the pages/page.x properties.
read-only, unsigned integer
Number of sampling periods that the Thermochron stayed out of range during a
mission. Each sampling period is mission/frequency minutes long.
read-only, ascii
End of time that the Thermochron went out of range during the current mission.
See clock/date for format.
Each period can be up to 255 samples in length, and span the time overtemp/date to overtemp/end ( or undertemp/date to undertemp/end ).
read-only, ascii
Time that the Thermochron went out of range during the current mission. See
clock/date for format.
read-only, unsigned integer
Number of entries (0 to 12) in the overtemp or undertemp
array.
read-write, floating point
Temperature limit to trigger alarm and error log. overtemp/temperature
gives upper limit and undertemp/temperature gives lower limit.
In current temperature scale.
read-only, unsigned integer
A numeric representation of overtemp/date or undertemp/date
The number of seconds in UNIX time (since Jan 1, 1970).
read-write, binary
Memory is split into 16 pages of 32 bytes each. User available. The log
memory, register banks and histogram data area are all separate from this
memory area.
ALL is an aggregate of the pages. Each page is accessed
sequentially.
read-only, floating point
Last temperature explicitly requested. Only available when the mission is not
in progress. Value returned in in the current temperature scale.
read-only, ascii
The entire 64-bit unique ID. Given as upper case hexadecimal digits (0-9A-F).
address starts with the family code
r address is the address in reverse order, which is often used
in other applications and labeling.
read-only, ascii
The 8-bit error correction portion. Uses cyclic redundancy check. Computed
from the preceding 56 bits of the unique ID number. Given as upper case
hexadecimal digits (0-9A-F).
read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper
case hexadecimal digits (0-9A-F).
read-only, ascii
The 48-bit middle portion of the unique ID number. Does not include the family
code or CRC. Given as upper case hexadecimal digits (0-9A-F).
r id is the id in reverse order, which is often used in other
applications and labeling.
read-only, ascii
Uses an extension of the 1-wire design from iButtonLink company that
associated 1-wire physical connections with a unique 1-wire code. If the
connection is behind a Link Locator the locator will show a unique
8-byte number (16 character hexadecimal) starting with family code FE.
If no Link Locator is between the device and the master, the
locator field will be all FF.
r locator is the locator in reverse order.
read-only, yes-no
Is the device currently present on the 1-wire bus?
read-only, ascii
Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging
(iButton vs chip) will not be distiguished.
None.
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 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.
The DS1921 (3) is an iButton device with many intriguing functions. Essentially it monitors temperature, giving both a log of readings, and a histogram of temperature ranges. The specification is somewhat complex, but OWFS hides many of the implementation details.
While on a mission the DS1921 (3) records temperature readings in a 2048-sample log and adds them to a 62-bin histogram.
All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form:
Addressing under OWFS is in hexadecimal, of form:
where 01 is an example 8-bit family code, and 12345678ABC is an example 48 bit address.
The dot is optional, and the CRC code can included. If included, it must be correct.
http://pdfserv.maxim-ic.com/en/ds/DS2438.pdf
http://pdfserv.maxim-ic.com/en/an/humsensor.pdf
owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1) owwrite (1) owpresent (1) owtap (1)
owfs (5) owtap (1) owmon (1)
owtcl (3) owperl (3) owcapi (3)
DS1427 (3) DS1904 (3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)
DS2401 (3) DS2411 (3) DS1990A (3)
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)
DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3) InfernoEmbedded (3)
DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921 (3) DS1821 (3) DS28EA00 (3) DS28E04 (3) EDS0064 (3) EDS0065 (3) EDS0066 (3) EDS0067 (3) EDS0068 (3) EDS0071 (3) EDS0072 (3) MAX31826 (3)
DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)
DS2450 (3)
DS2890 (3)
DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3) DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
DS2423 (3)
LCD (3) DS2408 (3)
DS1977 (3)
DS2406 (3) TAI8570 (3) EDS0066 (3) EDS0068 (3)
EEEF (3) DS2438 (3)
http://www.owfs.org
Paul Alfille (paul.alfille@gmail.com)
| 2005 | OWFS Manpage |