DS1977-F5- MAXIM [Maxim Integrated Products], DS1977-F5- Datasheet - Page 23

• Manufacturer Part Number: DS1977-F5-
• Description: Password-Protected 32KB EEPROM iButton
• Manufacturer: MAXIM [Maxim Integrated Products]

Figure 13. CRC16 HARDWARE DESCRIPTION AND POLYNOMIAL
COMMAND-SPECIFIC 1-Wire COMMUNICATION PROTOCOL—LEGEND
X
X
0
8
STAGE
STAGE
<data to EOS>
<data to EOP>
<PW/dummy>
Strong Pullup
1
9
<64 bytes>
Password
SYMBOL
th
st
CRC16\
AA loop
Version
FF loop
TA-E/S
<data>
Select
RST
CPS
00h
WS
RM
PD
RS
VP
RV
TA
X
X
9
1
STAGE
STAGE
10
2
nd
th
X
10
STAGE
1-Wire Reset Pulse Generated by Master
1-Wire Presence Pulse Generated by Slave
Command and Data to Satisfy the ROM Function Protocol
Command "Write Scratchpad"
Command "Read Scratchpad"
Command "Copy Scratchpad with Password"
Command "Read Memory with Password"
Command "Verify Password"
Command "Read Version"
Target Address TA1, TA2
Target Address TA1, TA2 with E/S Byte
Transfer of as Many Data Bytes as are Needed to Reach the Scratchpad Offset 3Fh
Transfer of as Many Data Bytes as are Needed to Reach the End of a Memory Page
Transfer of 8 Bytes that Either Represent a Valid Password or Acceptable Dummy Data
Transfer of 64 Bytes
Transfer of an Undetermined Amount of Data
Transmission of One Byte 00h
Transmission of Password
Transmission of Device Version Number
Transfer of an Inverted CRC16
Indefinite Loop Where the Master Reads FF Bytes
Indefinite Loop Where the Master Reads AA Bytes
Data Transfer to/from EEPROM (Data or Passwords Memory); No Activity on the 1-Wire
Bus Permitted During this Time
11
th
X
11
STAGE
X
12
2
STAGE
th
3
Polynomial = X
rd
X
12
STAGE
X
13
3
STAGE
th
4
th
X
13
23 of 29
STAGE
X
14
16
4
STAGE
+ X
th
5
th
X
15
14
DESCRIPTION
+ X
STAGE
X
15
5
STAGE
2
th
+ 1
6
th
INPUT DATA
X
6
STAGE
7
th
X
X
15
7
STAGE
STAGE
16
8
th
th
X
16
CRC
OUTPUT