DS1977 Maxim, DS1977 Datasheet - Page 13

• Manufacturer Part Number: DS1977
• Description: The DS1977 is a 32KB EEPROM in a rugged iButton® enclosure
• Manufacturer: Maxim

Figure 7-3. MEMORY/CONTROL FUNCTION FLOW CHART
From Figure 7
2
To Figure 7
2
nd
nd
Part
Part
Decision made
Decision made
by DS1977
by Master
Master TX
Reset
Y
N
TA1 (T7:T0), TA2 (T15:T8)
Command, Address, Data
(1
FFh if Password Address
from Memory Address or
DS1977 sets Memory
st
(Subsequent Passes)
Master RX Data Byte
Master RX CRC16 of
Address = (T15:T0)
64-Bits [Password]
Pass); CRC16 of Data
Master Activates
End of Page?
Strong Pullup
Read Mem.
Y
Accepted?
TX Reset?
Master TX
TX Reset?
CRC OK?
Master TX
Password
Memory?
[w/PW]
Master
Y
Master
End of
69h
N
Y
Y
Y
Y
13 of 29
N
N
N
N
N
Master RX "1"s
See
Note
ments Address
DS1977 Incre-
Counter
NOTE: The strong pullup
must be activated within
40µs after the last bit of the
password is transmitted.
Pullup duration: see t
To continue reading the next
memory page, the strong
pullup must be activated
within 40µs after the last bit
of the CRC16 is read.
Y
Master Activates
ments Address
DS1977 Incre-
Strong Pullup
Strong pull-
Counter
up valid?
SPUR
N
From Figure 7
To Figure 7
4
4
th
th
Part
Part
DS1977