DS1922L datasheet(21/48 Pages) DALLAS

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DS1922L/DS1922T

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MISSION TIME STAMP

The Mission Time Stamp indicates the date and time of the first temperature sample of the mission. There is only

read access to the Mission Time Stamp Register.

Mission Time Stamp Registers Bitmap

ADDR

0219h

10s

Single Seconds

021Ah

10min.

Single Minutes

021Bh

12/24

20hr

AM/PM

10hr

Single Hours

021Ch

10 Date

Single Date

021Dh

CENT

10m.

Single Months

021Eh

10yrs

Single Years

MISSION PROGRESS INDICATOR

Depending on settings in the Mission Control Register (address 0213h) the DS1922L/T will log temperature in 8-bit

or 16-bit format. The Mission Samples Counter together with the starting address and the logging format (8 or 16

bits) provides the information to identify valid blocks of data that have been gathered during the current (MIP = 1)

or latest mission (MIP = 0). See Datalog Memory Usage for an illustration.

Mission Samples Counter Register Map

ADDR

0220h

Low Byte

0221h

Center Byte

0222h

High Byte

There is only read access to this register.

The number read from the Mission Samples Counter indicates how often the DS1922L/T woke up during a mission

to measure temperature. The number format is 24-bit unsigned integer. The Mission Samples Counter is reset

through the Clear Memory command.

OTHER INDICATORS

The Device Samples Counter is similar to the Mission Samples Counter. During a mission this counter increments

whenever the DS1922L/T wakes up to measure and log data and when the device is testing for a temperature

alarm in SUTA mode. Between missions the counter increments whenever the Forced Conversion command is

executed. This way the Device Samples Counter functions like a gas gauge for the battery that powers the iButton.

Device Samples Counter Register Map

ADDR

0223h

Low Byte

0224h

Center Byte

0225h

High Byte

There is only read access to this register.

The Device Samples Counter is reset to zero when the iButton is assembled. The counter will increment a couple

of times during final test. The number format is 24-bit unsigned integer. The maximum number that can be

represented in this format is 16777215.

The Device Configuration Byte is used to allow the master to distinguish between the DS2422 chip, and different

versions of the DS1922 iButtons. The table below shows the codes assigned to the various devices.

DS1922L Datasheet(PDF) 21 Page - Dallas Semiconductor

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