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DS1921-Thermochron(3) One-Wire File System DS1921-Thermochron(3) NAME DS1921 - Thermochron temperature logging iButton. SYNOPSIS 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 ]] FAMILY CODE 21 SPECIAL PROPERTIES about/measuring read-only, yes-no Is this DS1921 currently measuring a temperature? about/resolution read-only, floating point What is the resolution of the temperature measurments (in the current temperature scale). about/samples read-only, unsigned integer How many total temperature measurements has this DS1921 performed? about/temphigh read-only, floating point Highest temperature this DS1921 can measure (in the current temperature scale). about/templow read-only, floating point Lowest temperature this DS1921 can measure (in the current temperature scale). about/version read-only, ascii Specific version of this DS1921. clock/date 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) clock/running 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 essen- tial for a mission. clock/udate read-write, unsigned integer A numeric representation of clock/date The number of seconds in UNIX time (since Jan 1, 1970). histogram/counts.0 ... histogram/counts.62 histogram/counts.ALL 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. histogram/elements read-only, unsigned integer The number of bins in the histogram. Always 63. histogram/gap 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. histogram/temperature.0 ... histogram/temperature.62 histogram/tempera- ture.ALL read-only, floating point Lower limit of the temperature range for the corresponding histogram bin. In the current temperature scale. log/date.0 ... log/date.2047 log/date.ALL 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 sam- ples 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 al- ways be a linear array of earliest to latest. ALL is the all data elements comma separated. log/elements 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 log/temperature.0 ... log/temperature.2047 log/temperature.ALL read-write, floating point The temperature readings (in the current temperature scale) that corre- spond to the log/date sample. See log/date for details on the indexing scheme and rollover behavior. log/udate.0 ... log/udate.2047 log/udate.ALL read-write, unsigned integer A numeric representation of log/date The number of seconds in UNIX time (since Jan 1, 1970). memory 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. overtemp/count.0 ... overtemp/count.11 overtemp/count.ALL undertemp/count.0 ... undertemp/count.11 undertemp/count.ALL 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. overtemp/end.0 ... overtemp/end.11 overtemp/end.ALL undertemp/end.0 ... undertemp/end.11 undertemp/end.ALL 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 ). overtemp/date.0 ... overtemp/date.11 overtemp/date.ALL undertemp/date.0 ... undertemp/date.11 undertemp/date.ALL read-only, ascii Time that the Thermochron went out of range during the current mission. See clock/date for format. overtemp/elements undertemp/elements read-only, unsigned integer Number of entries (0 to 12) in the overtemp or undertemp array. overtemp/temperature undertemp/temperature 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. overtemp/udate.0 ... overtemp/udate.11 overtemp/udate.ALL undertemp/udate.0 ... undertemp/udate.11 undertemp/udate.ALL read-only, unsigned integer A numeric representation of overtemp/date or undertemp/date The number of seconds in UNIX time (since Jan 1, 1970). pages/page.0 ... pages/page.15 pages/page.ALL 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. temperature 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. STANDARD PROPERTIES address r_address 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. crc8 read-only, ascii The 8-bit error correction portion. Uses cyclic redundancy check. Com- puted from the preceding 56 bits of the unique ID number. Given as up- per case hexadecimal digits (0-9A-F). family read-only, ascii The 8-bit family code. Unique to each type of device. Given as upper case hexadecimal digits (0-9A-F). id r_id 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 applica- tions and labeling. locator r_locator 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. present (DEPRECATED) read-only, yes-no Is the device currently present on the 1-wire bus? type read-only, ascii Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton vs chip) will not be distiguished. ALARMS None. DESCRIPTION 1-Wire 1-wire is a wiring protocol and series of devices designed and manufac- tured 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 (humid- ity, 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 en- cryption 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, par- allel, 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 in- dividual 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 com- munication. Still the fundamental goal has been ease of use, flexibil- ity and correctness rather than speed. DS1921 Thermochron The DS1921 (3) is an iButton device with many intriguing functions. Es- sentially 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. ADDRESSING All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form: Family Code 8 bits Address 48 bits CRC 8 bits Addressing under OWFS is in hexadecimal, of form: 01.123456789ABC 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. DATASHEET http://pdfserv.maxim-ic.com/en/ds/DS2438.pdf http://pdfserv.maxim-ic.com/en/an/humsensor.pdf 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) In- fernoEmbedded (3) Temperature 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) Humidity DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (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 (3) EDS0066 (3) EDS0068 (3) Moisture EEEF (3) DS2438 (3) AVAILABILITY http://www.owfs.org AUTHOR Paul Alfille (paul.alfille@gmail.com) OWFS Manpage 2005 DS1921-Thermochron(3)
NAME | SYNOPSIS | FAMILY CODE | SPECIAL PROPERTIES | STANDARD PROPERTIES | ALARMS | DESCRIPTION | ADDRESSING | DATASHEET | SEE ALSO | AVAILABILITY | AUTHOR
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