
1024-Bit EEPROM iButton
BUS MASTER Tx MEMORY
FUNCTION COMMAND
FROM ROM FUNCTIONS
FLOWCHART (FIGURE 9)
0Fh
WRITE SCRATCHPAD?
N
AAh
READ SCRATCHPAD?
N
TO FIGURE 7b
Y
BUS MASTER Tx
TA1 (T[7:0]), TA2 (T[15:8])
Y
BUS MASTER Rx
TA1 (T[7:0]), TA2 (T[15:8]),
AND E/S BYTE
DS1972
SETS PF = 1
CLEARS AA = 0
SETS E[2:0] = T[2:0]
DS1972 SETS
SCRATCHPAD
BYTE COUNTER = T[2:0]
MASTER Tx DATA BYTE
TO SCRATCHPAD
APPLIES ONLY
IF THE MEMORY
AREA IS NOT
DS1972
INCREMENTS
BYTE COUNTER
BUS MASTER Rx
DATA BYTE FROM
SCRATCHPAD
PROTECTED.
DS1972
INCREMENTS
E[2:0]
MASTER Tx RESET?
Y
IF WRITE PROTECTED ,
THE DS1972 COPIES
THE DATE BYTE FROM
THE TARGET ADDRESS
MASTER Tx RESET?
Y
N
INTO THE SCRATCHPAD.
IF IN EPROM MODE ,
N
N
E[2:0] = 7?
THE DS1972 LOADS
THE BITWISE LOGICAL
AND OF THE TRANSMITTED
N
BYTE COUNTER
BYTE AND THE DATA
= E[2:0]?
Y
T[2:0] = 0?
Y
PF = 0
N
BYTE FROM THE TARGETED
ADDRESS INTO THE
SCRATCHPAD.
Y
BUS MASTER Rx CRC-16
OF COMMAND, ADDRESS,
E/S BYTE, AND DATA BYTES
AS SENT BY THE DS1972
DS1972 Tx CRC-16 OF
COMMAND, ADDRESS,
AND DATA BYTES AS THEY
WERE SENT BY THE BUS
MASTER
BUS MASTER
Rx "1"s
N
MASTER Tx RESET?
Y
BUS MASTER
Rx "1"s
N
MASTER Tx RESET?
Y
FROM FIGURE 7b
TO ROM FUNCTIONS
FLOWCHART (FIGURE 9)
Figure 7a. Memory Function Flowchart
10
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