DS1921G
Thermochron iButton Device
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
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.
this CRC only if the reading continues through the end
POLYNOMIAL = X 16 + X 15 + X 2 + 1
X 0
1ST
STAGE
X 1
2ND
STAGE
X 2
3RD
STAGE
X 3
4TH
STAGE
X 4
5TH
STAGE
X 5
6TH
STAGE
X 6
7TH
STAGE
X 7
8TH
STAGE
9TH
STAGE
10TH
STAGE
11TH
STAGE
12TH
STAGE
13TH
STAGE
14TH
STAGE
15TH
STAGE
16TH
STAGE
X 8
X 9
X 10
X 11
X 12
X 13
X 14
X 15
X 16
CRC OUTPUT
INPUT DATA
Figure 16. CRC-16 Hardware Description and Polynomial
Command-Specific 1-Wire Communication Protocol—Legend
34
SYMBOL
RST
PD
Select
WS
RS
CPS
RM
RMC
CM
CT
TA
TA-E/S
<data to EOS>
<data to EOP>
<data to EOM>
<00 to EOP>
<32 bytes>
DESCRIPTION
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
Transfer of as many 00h bytes as are needed to reach a memory page boundary
Transfer of 32 bytes
Maxim Integrated
相关PDF资料
DS1921H-F5# IBUTTON THERMOCHRON F5
DS1921K# KIT IBUTTON THERMOCHRON
DS1922E-F5# IBUTTON TEMP LOGGER 4KBit F5
DS1922L-F5# IBUTTON TEMP LOGGER
DS1923-F5# IBUTTON TEMP/HUMIDITY LOGGER F5
DS1961S-F3# IBUTTON EEPROM 1KBit F3
DS1963S-F5+ IBUTTON MONETARY SHA-1
DS1971-F3+ IBUTTON EEPROM 256KBIT F3
相关代理商/技术参数
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DS1921G-F5/A12-W 功能描述:iButton RoHS:否 存储类型:SRAM 存储容量:512 B 组织: 工作电源电压:3 V to 5.25 V 接口类型:1-Wire 最大工作温度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封装 / 箱体:F5 MicroCan 制造商:Maxim Integrated
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DS1921G-F5/A17 功能描述:iButton RoHS:否 存储类型:SRAM 存储容量:512 B 组织: 工作电源电压:3 V to 5.25 V 接口类型:1-Wire 最大工作温度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封装 / 箱体:F5 MicroCan 制造商:Maxim Integrated
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