'\"
'\" Copyright (c) 2003-2006 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Device manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.TH DS1825 3  2006 "OWFS Manpage" "One-Wire File System"
.SH NAME
.B DS1825
\- Programmable Resolution 1-Wire Digital Thermometer with ID
.TP
.B MAX31826
\- Digital Temperature Sensor with 1Kb Lockable EEPROM
.TP
.B MAX31850 MAX31851
\- Cold-Junction Compensated Thermocouple
.SH SYNOPSIS
.SS Thermometer with hardware address pins (DS1825)
.PP
.B 3B
[.]XXXXXXXXXXXX[XX][/[
.B fasttemp
|
.B temperature
|
.B temperature9
|
.B temperature10
|
.B temperature11
|
.B temperature12
|
.B latesttemp
|
.B power
|
.B prog_addr
|
.B temphigh
|
.B templow
|
.B tempres
|
'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Program manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.B address
|
.B crc8
|
.B id
|
.B locator
|
.B r_address
|
.B r_id
|
.B r_locator
|
.B type
]]
.SS Digital Temperature Sensor with 1Kb Lockable EEPROM (MAX31826)
.PP
.B 3B
[.]XXXXXXXXXXXX[XX][/[
.B temperature
|
.B latesttemp
|
.B power
|
.B memory
|
.B pages/page.[0-15|ALL]
|
.B prog_addr
|
'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Program manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.B address
|
.B crc8
|
.B id
|
.B locator
|
.B r_address
|
.B r_id
|
.B r_locator
|
.B type
]]
.SS Cold-Junction Compensated Thermocouple (MAX31850 and MAX31851)
.PP
.B 3B
[.]XXXXXXXXXXXX[XX][/[
.B temperature
|
.B latesttemp
|
.B thermocouple
|
.B fault
|
.B open_circuit
|
.B ground_short
|
.B vdd_short
|
.B power
|
.B prog_addr
|
'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Program manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.B address
|
.B crc8
|
.B id
|
.B locator
|
.B r_address
|
.B r_id
|
.B r_locator
|
.B type
]]
.SH FAMILY CODE
.PP
.I 3B
.SH SPECIAL PROPERTIES
.SS power
.I read-only,yes-no
.br
Is the chip powered externally (=1) or from the parasitically from the data bus (=0)?
.SS prog_addr
.I read-only, 0-15
.br
A distiguishing feature of the
.B DS1825 (3)
is the ability to set hardware pins for an address (0-15). This is an alternative to the unique 64-bit
.I address
that is set in the factory.
.SS temperature
.I read-only, floating point
.br
Measured temperature with 12 bit resolution.
.P
For the 
.B MAX31850 MAX 31851
this is the
.I cold-junction temperature
-- the temperature at the chip. See
.I thermocouple
.SS temperature9 temperature10 temperature11 temperature12
.I read-only, floating point
(
.B DS1825 
only)
.P
Measured temperature at 9 to 12 bit resolution. There is a tradeoff of time versus accuracy in the temperature measurement.
.PP
The
.B MAX31826 MAX31850 MAX31851
measure all temperatures at 12 bit resoltion and will return that resolution to all the possible temperature properties.
.SS latesttemp
.I read-only, floating point
.br
Measured temperature at 9 to 12 bit resolution, depending on the resolution of the latest conversion on this chip. Reading this node will never trigger a temperature conversion. Intended for use in conjunction with
.B /simultaneous/temperature.
.SS fasttemp
.I read-only, floating point
.br
Equivalent to
.I temperature9
.SS thermocouple
.I read-only, floating point
(
.B MAX31850 MAX31851
only)
.P
Measured temperature of the thermocouple at 16bit resolution. Cold-junction temperature compensated.
.PP
The actual thermocouple type used is set by the selected chip type, and is not discoverable in software.
.SH TEMPERATURE ALARM LIMITS
When the device exceeds either
.I temphigh
or
.I templow
temperature threshold the device is in the alarm state, and will appear in the alarm directory. This provides an easy way to poll for temperatures that are unsafe, especially if 
.I simultaneous
temperature conversion is done.
.PP
Units for the temperature alarms are in the same
.I temperature scale
that was set for
.I temperature
measurements.
.PP
Temperature thresholds are stored in non-volatile memory and persist until changed, even if power is lost.
.SS temphigh
.I read-write, integer
.br
Shows or sets the lower limit for the high temperature alarm state. 
.SS templow
.I read-write, integer
.br
Shows or sets the upper limit for the low temperature alarm state. 
.PP
The
.B MAX31826
does NOT have temperature thresholds and temperature alarm.
.SH TEMPERATURE RESOLUTION DEFAULT VALUE
.SS tempres
.I read-write, integer
.br
The device employs a non-volatile memory to store the default temperature resolution (9, 10, 11 or 12 bits) to be applied after power-up. This is useful if you use
.I simultaneous
temperature conversions. Reading this node gives you the value stored in the non-volatile memory. Writing sets a new power-on resolution value.
.PP
As a side effect, reading this node resets the temperature resolution used by
.I simultaneous
temperature conversions to its power-on value. It also affects the resolution value used by
.B latesttemp,
to scale the latest conversion value, so make sure to re-sample the temperature before accessing
.B latesttemp
after writing or reading the
.B tempres
value.
.SH MEMORY
Only the
.B MAX31826
supports memory functions.
.SS pages/page.0 .. pages/page.15 pages/page.ALL
.I read/write, binary
.br
EEPROM memory pages of 8 bytes each. See the datasheet about locking contents.
.SS memory
.I read/write, binary
.br
EEPROM memory of 128 bytes. See the datasheet about locking contents.
.SH FAULT REPORTING
Only the
.B MAX31850 MAX31851
supports fault reporting.
.SS fault
.I read-only, yes-no
.br
Fault in last thermocouple conversion
.SS open_circuit
.I read-only, yes-no
.br
Thermocouple leads disconnected.
.SS ground_short
.I read-only, yes-no
.br
Thermocouple lead shorted to ground.
.SS vdd_short
.I read-only, yes-no
.br
Thermocouple lead shorted to supply voltage.
.SH STANDARD PROPERTIES
'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Program manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.SS address
.SS r_address
.I read-only, ascii
.br
The entire 64-bit unique ID. Given as upper case hexadecimal digits (0-9A-F).
.br
.I address
starts with the
.I family
code
.br
.I r address
is the
.I address
in reverse order, which is often used in other applications and labeling.
.SS crc8
.I read-only, ascii
.br
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).
.SS family
.I read-only, ascii
.br
The 8-bit family code. Unique to each
.I type
of device. Given as upper case hexadecimal digits (0-9A-F).
.SS id
.SS r_id
.I read-only, ascii
.br
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).
.br
.I r id
is the
.I id
in reverse order, which is often used in other applications and labeling.
.SS locator
.SS r_locator
.I read-only, ascii
.br
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
.B Link Locator
the
.I locator will show a unique 8-byte number (16 character hexadecimal) starting with family code FE.
.br
If no
.B Link Locator
is between the device and the master, the
.I locator
field will be all FF.
.br
.I r locator
is the
.I locator
in reverse order.
.SS present (DEPRECATED)
.I read-only, yes-no
.br
Is the device currently
.I present
on the 1-wire bus?
.SS type
.I read-only, ascii
.br
Part name assigned by Dallas Semi. E.g.
.I DS2401
Alternative packaging (iButton vs chip) will not be distiguished.
.SH DESCRIPTION
'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Program manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.SS 1-Wire
.I 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.
.PP
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.
.PP
The 1-wire scheme uses a single 
.I bus master
and multiple
.I slaves
on the same wire. The bus master initiates all communication. The slaves can be 
individually discovered and addressed using their unique ID.
.PP
Bus masters come in a variety of configurations including serial, parallel, i2c, network or USB
adapters.
.SS OWFS design
.I 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.
.PP 
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.
.SS DS1825
The
.B DS1825 (3)
is one of several available 1-wire temperature sensors. Alternatives are the
.B DS18S20 (3),
.B DS18B20 (3),
and
.B DS1822 (3)
as well as temperature/voltage measurements in the
.B DS2436 (3)
and
.B DS2438 (3).
For truly versatile temperature measurements, see the protean
.B DS1921 (3) Thermachron (3).
.PP
The
.B DS1825 (3)
can select between 4 resolutionsspanning the fastest/roughest and slowest/best.
.SS MAX31826
The
.B MAX31826
shares a family code with the
.B DS1825
but has differences in some of its functions.
.PP
The 
.B MAX31826
has 128 btes of EEPROM memory (as 16 pages of 8 bytes) while the
.B DS1825
has no memory available.
.PP
The 
.B MAX31826
measures temperature at 12 bit resolution as fast as the 
.B DS1825's
lowest resolution (and always uses 12-bit resolution). On the other hand it has no temperature thresholds or alarm function.
.SH ADDRESSING
'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Program manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form:
.TP
.B Family Code
8 bits
.TP
.B Address
48 bits
.TP
.B CRC
8 bits
.IP
.PP
Addressing under OWFS is in hexadecimal, of form:
.IP
.B 01.123456789ABC
.PP
where
.B 01
is an example 8-bit family code, and
.B 12345678ABC
is an example 48 bit address.
.PP
The dot is optional, and the CRC code can included. If included, it must be correct.
.PP
Both the
.B MAX31826
and the 
.B DS1825
allow hardware selection of part of the address, which can assist selecting between chips is some circuit designs.
.SH DATASHEET
.TP
.B DS1825
http://pdfserv.maxim-ic.com/en/ds/DS1825.pdf
.TP
.B MAX31826
http://datasheets.maxim-ic.com/en/ds/MAX31826.pdf
.SH SEE ALSO
.SS Programs
.B owfs (1) owhttpd (1) owftpd (1) owserver (1)
.B owdir (1) owread (1) owwrite (1) owpresent (1)
.B owtap (1)
.SS Configuration and testing
.B owfs (5) owtap (1) owmon (1)
.SS Language bindings
.B owtcl (3) owperl (3) owcapi (3)
.SS Clocks
.B DS1427 (3) DS1904 (3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)
.SS ID
.B DS2401 (3) DS2411 (3) DS1990A (3)
.SS Memory
.B 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)
.SS Switches
.B DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3) InfernoEmbedded (3)
.SS Temperature
.B 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)
.SS Humidity
.B DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)
.SS Voltage
.B DS2450 (3)
.SS Resistance
.B DS2890 (3)
.SS Multifunction (current, voltage, temperature)
.B DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3) DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
.SS Counter
.B DS2423 (3)
.SS LCD Screen
.B LCD (3) DS2408 (3)
.SS Crypto
.B DS1977 (3)
.SS Pressure
.B DS2406 (3) TAI8570 (3) EDS0066 (3) EDS0068 (3)
.SS Moisture
.B EEEF (3) DS2438 (3)
.SH AVAILABILITY
http://www.owfs.org
.SH AUTHOR
Paul Alfille (paul.alfille@gmail.com)