DS1921H/Z Maxim Integrated Products, DS1921H/Z Datasheet - Page 11

• Manufacturer Part Number: DS1921H/Z
• Description: High Resolution Thermochron Ibutton Range H
• Manufacturer: Maxim Integrated Products

MISSION TIME STAMP
When a mission is started, a copy of the RTC Registers addresses 0201h, 0202h, and 0204h to 0206h is
saved as the Mission Time Stamp. The Mission Time Stamp does not indicate the time of the first
temperature conversion of a mission. To calculate the time of the first conversion, add to the Mission
Time Stamp as many minutes as specified in the Sample Rate Register plus the value of the Mission Start
Delay. Subsequent temperature conversions will take place as many minutes apart from each other as
specified by the value in the Sample Rate Register. Mission samples occur on minute boundaries.
Mission Time Stamp Register Bitmap
MISSION SAMPLES COUNTER
The Mission Samples Counter indicates how many temperature measurements have taken place during
the current mission in progress (if MIP = 1) or during the latest mission (if MIP = 0). The value is stored
as an unsigned 24-bit integer number. This counter is reset through the Clear Memory command.
Mission Samples Counter Register Map
DEVICE SAMPLES COUNTER
The Device Samples Counter indicates how many temperature measurements have taken place since the
device was assembled at the factory. The value is stored as an unsigned 24-bit integer number. The
maximum number that can be represented in this format is 16777215, which is higher than the expected
lifetime of the DS1921H/Z iButton. This counter cannot be reset under software control.
Device Samples Counter Register Map
TEMPERATURE LOGGING AND HISTOGRAM
Once setup for a mission, the DS1921H/Z logs the temperature measurements simultaneously byte after
byte in the datalog memory as well as in histogram form in the histogram memory. The datalog memory
is able to store 2048 temperature values measured at equidistant time points. The first temperature value
of a mission is written to address location 1000h of the datalog memory, the second value to address
location 1001h and so on. Knowing the starting time point (Mission Time Stamp), the interval between
temperature measurements and the Mission Start Delay, one can reconstruct the time and date of each
measurement.
021Ah
021Bh
021Ch
021Dh
021Eh
ADDR
0215h
0216h
0217h
0218h
0219h
ADDR
ADDR
021Fh
b7
b7
b7
0
0
0
0
12/24
b6
b6
b6
0
0
10 Years
10 Minutes
AM/PM
20h.
b5
b5
b5
0
10 Date
10m.
10h.
b4
b4
b4
Center Byte
Center Byte
High Byte
High Byte
Low Byte
Low Byte
b3
b3
b3
11 of 40
Single Minutes
Single Months
Single Hours
Single Years
b2
b2
b2
Single Date
b1
b1
b1
b0
b0
b0