Datasheet

DS1922L/DS1922T
Temperature Logger iButton with 8KB
Data-Log Memory
______________________________________________________________________________________ 31
MASTER Tx MEMORY OR
CONTROL FUNCTION COMMAND
MASTER Tx
TA1 [T7:T0]
MASTER Tx DATA BYTE
TO SCRATCHPAD OFFSET
DS1922
INCREMENTS
SCRATCHPAD
OFFSET
DS1922 SETS
SCRATCHPAD OFFSET = [T4:T0]
AND CLEARS (PF, AA)
0Fh
WRITE SCRATCHPAD?
N
Y
Y
N
Y
N
N
Y
N
MASTER Tx RESET?
SCRATCHPAD
OFFSET = 11111b?
MASTER Tx RESET?
MASTER Tx RESET?
MASTER Tx
TA2 [T15:T8]
DS1922 SETS [E4:E0] =
SCRATCHPAD OFFSET
N
FROM ROM FUNCTIONS
FLOWCHART (FIGURE 11)
TO ROM FUNCTIONS
FLOWCHART (FIGURE 11)
Y
Y
TO FIGURE 9b
FROM FIGURE 9b
MASTER Rx CRC-16 OF
COMMAND, ADDRESS DATA
MASTER Rx "1"s
PARTIAL
BYTE WRITTEN?
PF = 1
AA = 1
MASTER Rx
TA1 [T7:T0]
DS1922 SETS
SCRATCHPAD OFFSET = [T4:T0]
DS1922
INCREMENTS
SCRATCHPAD
OFFSET
MASTER Rx ENDING OFFSET
WITH DATA STATUS
(E/S)
AAh
READ SCRATCHPAD?
N
Y
Y
N
Y
N
Y
N
MASTER Tx RESET?
SCRATCHPAD
OFFSET = 11111b?
MASTER Tx RESET?
MASTER Rx
TA2 [T15:T8]
MASTER Rx DATA BYTE FROM
SCRATCHPAD OFFSET
MASTER Rx CRC-16 OF
COMMAND, ADDRESS DATA,
E/S BYTE, AND DATA STARTING
AT THE TARGET ADDRESS
MASTER Rx "1"s
99h
COPY SCRATCHPAD
[WITH PW]
N
Y
Y
N
N
MASTER Tx RESET?
MASTER Tx RESET?
COPYING
FINISHED
MASTER Tx
E/S BYTE
MASTER Tx
TA1 [T7:T0], TA2 [T15:T8]
AUTHORIZATION
CODE
MASTER Tx
64 BITS [PASSWORD]
DS1922 COPIES SCRATCHPAD
DATA TO MEMORY
N
Y
AUTHORIZATION
CODE MATCH?
N
Y
N
Y
Y
N
MASTER Tx RESET?
Y
PASSWORD
ACCEPTED?
DS1922 Tx "0"
DS1922 Tx "1"
MASTER Rx "1"s MASTER Rx "1"s
Figure 9a. Memory/Control Function Flowchart