DS1921K# Maxim Integrated Products, DS1921K# Datasheet - Page 39

• Manufacturer Part Number: DS1921K#
• Description: KIT IBUTTON THERMOCHRON
• Manufacturer: Maxim Integrated Products
• Series: iButton®r

Specifications of DS1921K#

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Memory Type: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Step 3: Set the search condition and Mission Start Delay and clear the alarm flags
In this example, the rollover is disabled and the search condition is set for a high temperature only. The mission is
to start with a delay of 90min (005Ah) and the alarm flags TLF, THF, and TAF are cleared. This results in the follow-
ing data to be written to the special function registers:
With only a single DS1921G connected to the bus master, the communication of step 3 is as follows:
* Writing through address locations 20Fh to 211h is faster than accessing the Mission Start Delay register in a separate cycle. The
write attempt has no effect on the contents of these registers.
ADDRESS
MASTER MODE
DATA
Rx
Rx
Rx
Rx
Rx
Rx
Rx
Rx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
______________________________________________________________________________________
20Eh
02h
DATA (LSB FIRST)
<7 data bytes>
<7 data bytes>
20Fh
00h*
(Presence)
(Presence)
(Presence)
(Presence)
(Reset)
(Reset)
(Reset)
(Reset)
CCh
CCh
CCh
AAh
0Eh
0Eh
0Eh
0Fh
02h
02h
14h
55h
02h
13h
210h
00h*
Reset Pulse (480μs to 960μs)
Presence pulse
Issue Skip ROM command
Issue Write Scratchpad command
TA1, beginning offset = 0Eh
TA2, address = 020Eh
Write 7 bytes of data to scratchpad
Reset pulse
Presence pulse
Issue Skip ROM command
Issue Read Scratchpad command
Read TA1, beginning offset = 0Eh
Read TA2, address = 020Eh
Read E/S, ending offset = 14h, 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
211h
00h*
Thermochron iButton
(AUTHORIZATION CODE)
212h
5Ah
COMMENTS
213h
00h
214h
00h
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