Rainbow Electronics DS1972 - Manual (Page 9)

DS1972: 1024-Bit EEPROM iButton
9 of 23
Figure 7-1. Memory Function Flow Chart
0Fh
Write Scratch-
pad ?
Bus Master TX
TA1 (T7:T0), TA2 (T15:T8)
Y
N
To Figure 7
2 nd Part
From Figure 7
2 nd Part
Bus Master TX Memory
Function Command
To ROM Functions
Flow Chart (Figure 9)
From ROM Functions
Flow Chart (Figure 9)
Applies only if the
memory area is not
protected.
If write-protected, then
the DS1972 copies the
data byte from the tar-
get address into the SP.
If in EPROM mode,
then the DS1972 loads
the bitwise logical AND
of the transmitted byte
and the data byte from
the targeted address
into the SP.
Master
TX Reset ?
Master TX Data Byte
To Scratchpad
DS1972 sets
Sets PF = 1
Clears AA = 0
Sets E2:E0 = T2:T0
DS1972
Increments
E2:E0
Master
TX Reset ?
Y
DS1972 TX CRC16
of Command, Address,
Data Bytes as they were
sent by the bus master
N
Y
PF = 0
N
Y
E2:E0
= 7 ?
Bus Master
RX “1”s
N
N
Y
T2:T0
= 0 ?