DS1921Z-F5# Maxim Integrated Products, DS1921Z-F5# Datasheet - Page 34

• Manufacturer Part Number: DS1921Z-F5#
• Description: IBUTTON THERMOCHRON F5
• Manufacturer: Maxim Integrated Products
• Series: iButton®r

Specifications of DS1921Z-F5#

• Rohs Information: IButton RoHS Compliance Plan
• Memory Size: 512B
• Memory Type: NVSRAM (Non-Volatile SRAM)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Thermochron iButton
With the Read Scratchpad command, the CRC is gen-
erated by first clearing the CRC generator and then
shifting in the command code, the target addresses
TA1 and TA2, the E/S byte, and the scratchpad data
starting at the target address. The DS1921G transmits
this CRC only if the reading continues through the end
Figure 16. CRC-16 Hardware Description and Polynomial
34
<data to EOM>
<data to EOS>
<data to EOP>
X
______________________________________________________________________________________
8
X
SYMBOL
0
TA-E/S
Select
STAGE
RMC
RST
CPS
RM
CM
9TH
WS
PD
RS
CT
TA
STAGE
1ST
X
9
X
1
STAGE
10TH
STAGE
Command-Specific 1-Wire Communication Protocol—Legend
2ND
1-Wire reset pulse generated by master
1-Wire presence pulse generated by slave
Command and data to satisfy the ROM function protocol (Skip ROM, Search ROM, etc.)
Command: “Write Scratchpad”
Command: “Read Scratchpad”
Command: “Copy Scratchpad”
Command: “Read Memory”
Command: “Read Memory with CRC”
Command: “Clear Memory”
Command: “Convert Temperature”
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 1Fh
Transfer of as many data bytes as are needed to reach the end of a memory page
Transfer of as many data bytes as are needed to reach the end of the data-log memory
X
10
STAGE
11TH
X
11
X
2
STAGE
12TH
STAGE
3RD
X
POLYNOMIAL = X
12
X
3
STAGE
13TH
STAGE
4TH
X
13
16
X
+ X
4
STAGE
14TH
15
of the scratchpad, regardless of the actual ending off-
set. For more information on generating CRC values
refer to Application Note 27: Understanding and Using
Cyclic Redundancy Checks with Maxim iButton
Products.
STAGE
+ X
5TH
DESCRIPTION
2
+ 1
X
14
X
5
STAGE
15TH
STAGE
6TH
X
6
STAGE
7TH
X
15
X
INPUT DATA
7
STAGE
16TH
STAGE
8TH
X
16
CRC OUTPUT