1024-Bit EEPROM iButton

14

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DS1972 Tx

PRESENCE PULSE

BUS MASTER Tx

RESET PULSE

BUS MASTER Tx ROM

FUNCTION COMMAND

DS1972 Tx

CRC BYTE

DS1972 Tx

FAMILY CODE

(1 BYTE)

DS1972 Tx

SERIAL NUMBER

(6 BYTES)

RC = 0

MASTER Tx BIT 0

RC = 0

RC = 0

RC = 0

OD = 0

Y

Y

Y

Y

Y

Y

Y

Y

33h

READ ROM

COMMAND?

N

55h

MATCH ROM

COMMAND?

BIT 0 MATCH?

BIT 0 MATCH?

N

N

N

N

N

N

N

F0h

SEARCH ROM

COMMAND?

OD

RESET PULSE?

N

N

CCh

SKIP ROM

COMMAND?

N

RC = 1

MASTER Tx BIT 1

MASTER Tx BIT 63

BIT 1 MATCH?

BIT 63 MATCH?

Y

Y

RC = 1

FROM MEMORY FUNCTIONS

FLOWCHART (FIGURE 7)

TO MEMORY FUNCTIONS

FLOWCHART (FIGURE 7)

DS1972 Tx BIT 0

DS1972 Tx BIT 0

MASTER Tx BIT 0

BIT 1 MATCH?

BIT 63 MATCH?

DS1972 Tx BIT 1

DS1972 Tx BIT 1

MASTER Tx BIT 1

DS1972 Tx BIT 63

DS1972 Tx BIT 63

MASTER Tx BIT 63

Y

TO FIGURE 9b

TO FIGURE 9b

FROM FIGURE 9b

FROM FIGURE 9b

Figure 9a. ROM Functions Flowchart