DS1825(3) One-Wire File System DS1825(3)NAME
DS1825 - Programmable Resolution 1-Wire Digital Thermometer with ID
MAX31826
- Digital Temperature Sensor with 1Kb Lockable EEPROM
MAX31850 MAX31851
- Cold-Junction Compensated Thermocouple
SYNOPSIS
Thermometer with hardware address pins (DS1825)
3B [.]XXXXXXXXXXXX[XX][/[ | power | prog_addr | temphigh | templow | ]]
Digital Temperature Sensor with 1Kb Lockable EEPROM (MAX31826)
3B [.]XXXXXXXXXXXX[XX][/[ temperature | power | memory |
pages/page.[0-15|ALL] | prog_addr | ]]
Cold-Junction Compensated Thermocouple (MAX31850 and MAX31851)
3B [.]XXXXXXXXXXXX[XX][/[ temperature | thermocouple | fault |
open_circuit | ground_short | vdd_short | power | prog_addr | ]]
FAMILY CODE
3B
SPECIAL PROPERTIES
power
read-only,yes-no
Is the chip powered externally (=1) or from the parasitically from the
data bus (=0)?
prog_addr
read-only, 0-15
A distiguishing feature of the DS1825 (3) is the ability to set hard‐
ware pins for an address (0-15). This is an alternative to the unique
64-bit address that is set in the factory.
temperature
read-only, floating point
Measured temperature with 12 bit resolution.
For the MAX31850 MAX 31851 this is the cold-junction temperature -- the
temperature at the chip. See thermocouple
temperature9 temperature10 temperature11 temperature12
read-only, floating point ( DS1825 only)
Measured temperature at 9 to 12 bit resolution. There is a tradeoff of
time versus accuracy in the temperature measurement.
The MAX31826 MAX31850 MAX31851 measure all temperatures at 12 bit
resoltion and will return that resolution to all the possible tempera‐
ture properties.
fasttemp
read-only, floating point
Equivalent to temperature9
thermocouple
read-only, floating point ( MAX31850 MAX31851 only)
Measured temperature of the thermocouple at 16bit resolution. Cold-
junction temperature compensated.
The actual thermocouple type used is set by the selected chip type, and
is not discoverable in software.
The MAX31826 does NOT have temperature thresholds and temperature
alarm.
MEMORY
Only the MAX31826 supports memory functions.
pages/page.0 .. pages/page.15 pages/page.ALL
read/write, binary
EEPROM memory pages of 8 bytes each. See the datasheet about locking
contents.
memory
read/write, binary
EEPROM memory of 128 bytes. See the datasheet about locking contents.
FAULT REPORTING
Only the MAX31850 MAX31851 supports fault reporting.
fault
read-only, yes-no
Fault in last thermocouple conversion
open_circuit
read-only, yes-no
Thermocouple leads disconnected.
ground_short
read-only, yes-no
Thermocouple lead shorted to ground.
vdd_short
read-only, yes-no
Thermocouple lead shorted to supply voltage.
STANDARD PROPERTIESDESCRIPTION
DS1825
The DS1825 (3) is one of several available 1-wire temperature sensors.
Alternatives are the DS18S20 (3), DS18B20 (3), and DS1822 (3) as well
as temperature/voltage measurements in the DS2436 (3) and DS2438 (3).
For truly versatile temperature measurements, see the protean DS1921
(3) Thermachron (3).
The DS1825 (3) can select between 4 resolutionsspanning the
fastest/roughest and slowest/best.
MAX31826
The MAX31826 shares a family code with the DS1825 but has differences
in some of its functions.
The MAX31826 has 128 btes of EEPROM memory (as 16 pages of 8 bytes)
while the DS1825 has no memory available.
The MAX31826 measures temperature at 12 bit resolution as fast as the
DS1825's lowest resolution (and always uses 12-bit resolution). On the
other hand it has no temperature thresholds or alarm function.
ADDRESSING
Both the MAX31826 and the DS1825 allow hardware selection of part of
the address, which can assist selecting between chips is some circuit
designs.
DATASHEET
DS1825 http://pdfserv.maxim-ic.com/en/ds/DS1825.pdf
MAX31826
http://datasheets.maxim-ic.com/en/ds/MAX31826.pdf
SEE ALSOAVAILABILITY
http://www.owfs.org
AUTHOR
Paul Alfille (paul.alfille@gmail.com)
OWFS Manpage 2006 DS1825(3)
