
DS1922E
iButton High-Temperature Logger with
8KB Data-Log Memory
With only a single device connected to the bus master,
the communication of step 2 looks like this:
MASTER MODE
Tx
Rx
Tx
Tx
Tx
Tx
Tx
Tx
Tx
Rx
Tx
Tx
Rx
Rx
Rx
Rx
Tx
Rx
Tx
Tx
Tx
DATA (LSB FIRST)
(Reset)
(Presence)
CCh
0Fh
00h
02h
<25 Data Bytes>
<7 FFh Bytes>
(Reset)
(Presence)
CCh
AAh
00h
02h
1Fh
<32 Data Bytes>
(Reset)
(Presence)
CCh
99h
00h
COMMENTS
Reset pulse
Presence pulse
Issue “Skip ROM ” command
Issue “Write Scratchpad” command
TA1, beginning offset = 00h
TA2, address = 0200h
Write 25 bytes of data to scratchpad
Write through the end of the scratchpad
Reset pulse
Presence pulse
Issue “Skip ROM ” command
Issue “Read Scratchpad” command
Read TA1, beginning offset = 00h
Read TA2, address = 0200h
Read E/S, ending offset = 1Fh, flags = 0h
Read scratchpad data and verify
Reset pulse
Presence pulse
Issue “Skip ROM ” command
Issue “Copy Scratchpad” command
TA1
Tx
02h
TA2
(AUTHORIZATION CODE)
Tx
Tx
Tx
Rx
1Fh
<8 FFh Bytes>
(Reset)
(Presence)
E/S
Send dummy password
Reset pulse
Presence pulse
Step 3: Start the new mission.
With only a single device connected to the bus master,
the communication of step 3 looks like this:
If step 3 was successful, the MIP bit in the General
Status register is 1, the MEMCLR bit is 0, and the mis-
sion start delay counts down.
42
MASTER MODE
Tx
Rx
Tx
Tx
Tx
Tx
Tx
Rx
DATA (LSB FIRST)
(Reset)
(Presence)
CCh
CCh
<8 FFh Bytes>
FFh
(Reset)
(Presence)
COMMENTS
Reset pulse
Presence pulse
Issue “Skip ROM ” command
Issue “Start Mission ” command
Send dummy password
Send dummy byte
Reset pulse
Presence pulse
Maxim Integrated