Datasheet

DS1921H/Z
33 of 45
CRC-16 HARDWARE DESCRIPTION AND POLYNOMIAL Figure 16
Polynomial = X
16
+ X
15
+ X
2
+ 1
X
0
X
1
X
2
X
3
X
4
X
5
X
6
X
7
X
8
X
9
X
10
X
11
X
12
X
13
X
14
X
15
X
16
1
st
STAGE
2
nd
STAGE
3
rd
STAGE
4
th
STAGE
6
th
STAGE
5
th
STAGE
7
th
STAGE
8
th
STAGE
9
th
STAGE
10
th
STAGE
11
th
STAGE
12
th
STAGE
13
th
STAGE
14
th
STAGE
15
th
STAGE
16
th
STAGE
INPUT DATA
CRC
OUTPUT
Command-Specific 1-Wire Communication Protocol — Legend
Symbol Description
RST
1-Wire Reset Pulse generated by master
PD
1-Wire Presence Pulse generated by slave
Select
Command and data to satisfy the ROM function protocol (Skip ROM, Search ROM, etc.)
WS
Command "Write Scratchpad"
RS
Command "Read Scratchpad"
CPS
Command "Copy Scratchpad"
RM
Command "Read Memory"
RMC
Command "Read Memory with CRC"
CM
Command "Clear Memory"
CT
Command "Convert Temperature"
TA
Target Address TA1, TA2
TA-E/S
Target Address TA1, TA2 with E/S byte
<data to EOS>
Transfer of as many data bytes as are needed to reach the scratchpad offset 1Fh
<data to EOP>
Transfer of as many data bytes as are needed to reach the end of a memory page
<data to EOM>
Transfer of as many data bytes as are needed to reach the end of the datalog memory
<00 to EOP>
Transfer of as many 00h bytes as are needed to reach a memory page boundary
<32 bytes>
Transfer of 32 bytes
<data>
Transfer of an undetermined amount of data
CRC16\
Transfer of an inverted CRC16
FF loop
Indefinite loop where the master reads FFh bytes
AA loop
Indefinite loop where the master reads AAh bytes
Busy
Interval during Copy Scratchpad where the DS1921H/Z does not respond. Any bits read
during this time are logic 1.
00 loop
Indefinite loop where the master reads 00h bytes