DS1921H/Z Maxim Integrated Products, DS1921H/Z Datasheet - Page 35

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

STEP 4
In this example, the temperature alarms are set to 0°C for the low temperature threshold and 10°C for the
high temperature threshold, assuming it is a DS1921Z device. The sample rate is once every 10 minutes,
allowing the mission to last up to 14 days. This results in the following data to be written to the special
function registers:
With only a single DS1921H/Z connected to the bus master, the communication of step 4 is as follows:
If step 4 was successful, the Mission Time Stamp Register will contain the date and time of the RTC, the
MIP bit in the Status Register will be 1, and the MEMCLR bit will be 0.
Address:
Data:
MASTER MODE
RX
RX
RX
RX
RX
RX
RX
RX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
20Bh
2Ch
20Ch
7Ch
DATA (LSB FIRST)
<3 data bytes>
<3 data bytes>
(Presence)
(Presence)
(Presence)
(Presence)
(Reset)
(Reset)
(Reset)
(Reset)
CCh
CCh
CCh
AAh
0Bh
0Bh
0Dh
0Bh
0Dh
0Fh
02h
02h
55h
02h
20Dh
0Ah
35 of 40
COMMENTS
Reset pulse (480µs to 960µs)
Presence pulse
Issue Skip ROM command
Issue Write Scratchpad command
TA1, beginning offset = 0Bh
TA2, address = 020Bh
Write 3 bytes of data to scratchpad
Reset pulse
Presence pulse
Issue Skip ROM command
Issue Read Scratchpad command
Read TA1, beginning offset = 0Bh
Read TA2, address = 020Bh
Read E/S, ending offset = 0Dh, flags = 0h
Read scratchpad data and verify
Reset pulse
Presence pulse
Issue Skip ROM command
Issue Copy Scratchpad command
TA1
TA2
E/S
Reset pulse
Presence pulse
(AUTHORIZATION CODE)