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DS24B33
1-Wire 4Kb EEPROM
Memory Access
Address Registers and Transfer Status
The DS24B33 employs three address registers: TA1,
TA2, and E/S (Figure 6). Registers TA1 and TA2 must
be loaded with the target address to which the data is
written or from which data is read. Register E/S is a
read-only transfer status register used to verify data
integrity with write commands. ES bits E[4:0] are
loaded with the incoming T[4:0] on a Write Scratchpad
command and increment on each subsequent data
byte. This is, in effect, a byte-ending offset counter
within the 32-byte scratchpad. Bit 5 of the E/S register,
called the partial byte flag (PF), is set if the number of
data bits sent by the master is not an integer multiple of
8 or if the data in the scratchpad is not valid due to a
loss of power. A valid write to the scratchpad clears the
PF bit. Bit 6 has no function; it always reads 0. The
highest valued bit of the E/S register, called authoriza-
tion accepted (AA), is valid only if the PF flag reads 0. If
PF is 0 and AA is 1, the data stored in the scratchpad
has already been copied to the target memory address.
Writing data to the scratchpad clears this flag.
Writing with Verification
To write data to the DS24B33, the scratchpad must be
used as intermediate storage. First, the master issues
the Write Scratchpad command to specify the desired
target address, followed by the data to be written to the
scratchpad. Under certain conditions (see the Write
Scratchpad [0Fh] section) the master receives an
inverted CRC-16 of the command, address, and data at
the end of the Write Scratchpad command sequence.
Knowing this CRC value, the master can compare it to
the value it has calculated itself to decide if the commu-
nication was successful and proceed to the Copy
Scratchpad command. If the master could not receive
the CRC-16, it should send the Read Scratchpad com-
mand to verify data integrity. As a preamble to the
scratchpad data, the DS24B33 repeats the target
address TA1 and TA2 and sends the contents of the
E/S register. If the PF flag is set, data did not arrive cor-
rectly in the scratchpad or there was a loss of power
since data was last written to the scratchpad. The mas-
ter does not need to continue reading; it can start a
new trial to write data to the scratchpad. Similarly, a set
AA flag together with a cleared PF flag indicates that
the device did not recognize the write command. If
everything went correctly, both flags are cleared and
the ending offset indicates the address of the last byte
written to the scratchpad. Now the master can continue
reading and verifying every data byte. After the master
has verified the data, it can send the Copy Scratchpad
command, for example. This command must be fol-
lowed exactly by the data of the three address registers
TA1, TA2, and E/S. The master should obtain the con-
tents of these registers by reading the scratchpad. As
soon as the DS24B33 has received these bytes correctly,
it starts copying the scratchpad data to the requested
location.
BIT NUMBER
TARGET ADDRESS (TA1)
TARGET ADDRESS (TA2)
7
T7
T15
6
T6
T14
5
T5
T13
4
T4
T12
3
T3
T11
2
T2
T10
1
T1
T9
0
T0
T8
ENDING ADDRESS WITH
DATA STATUS (E/S)
AA
0
PF
E4
E3
E2
E1
E0
(READ ONLY)
Figure 6. Address Registers
8
Maxim Integrated
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相关代理商/技术参数
DS24B33G+U
功能描述:电可擦除可编程只读存储器 1-WIRE 4KB 电可擦除可编程只读存储器 RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
DS24B33Q+T&R
制造商:Maxim Integrated Products 功能描述:1-WIRE 4KB EEPROM - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC EEPROM 4KBIT 6TDFN 制造商:Maxim Integrated Products 功能描述:EEPROM 1-Wire 4kbit EEPROM
DS24B33Q+T&R
功能描述:电可擦除可编程只读存储器 1-Wire 4kbit 电可擦除可编程只读存储器 RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
DS24B33Q+U
功能描述:电可擦除可编程只读存储器 1-WIRE 4KB 电可擦除可编程只读存储器 RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
DS24B33S
制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM
DS24B33S R
制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM
DS24B33S T
制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM
DS24B33S TR
制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM