參數(shù)資料
型號(hào)： DS1985
英文描述： 16-kbit Add-Only iButton
中文描述： 16K位只添加iButton®
文件頁(yè)數(shù)： 7/25頁(yè)
文件大?。?/td> 440K
代理商： DS1985
DS1985
7 of 25
The Status Memory address range of the DS1985 extends from 000 to 13FH. The memory locations
008H to 01FH, 028H to 03FH, 048H to 0FFH and 140H to 7FFH are physically not implemented.
Reading these locations will usually result in FFH bytes. Attempts to write to these locations will be
ignored. If the bus master sends a starting address higher than 7FFH, the five most significant address bits
are set to 0s by the internal circuitry of the chip. This will result in a mismatch between the CRC
calculated by the DS1985 and the CRC calculated by the bus master, indicating an error condition.
MEMORY FUNCTION COMMANDS
The “Memory Function Flow Chart” (Figure 5) describes the protocols necessary for accessing the
various data fields within the DS1985. The Memory Function Control section, 8-bit scratchpad, and the
Program Voltage Detect circuit combine to interpret the commands issued by the bus master and create
the correct control signals within the device. A 3-byte protocol is issued by the bus master. It is comprised
of a command byte to determine the type of operation and two address bytes to determine the specific
starting byte location within a data field. The command byte indicates if the device is to be read or
written. Writing data involves not only issuing the correct command sequence but also providing a 12V
programming voltage at the appropriate times. To execute a write sequence, a byte of data is first loaded
into the scratchpad and then programmed into the selected address. Write sequences always occur a byte
at a time. To execute a read sequence, the starting address is issued by the bus master and data is read
from the part beginning at that initial location and continuing to the end of the selected data field or until
a reset sequence is issued. All bits transferred to the DS1985 and received back by the bus master are sent
least significant bit first.
READ MEMORY [F0H]
The Read Memory command is used to read data from the 16384-bits EPROM data field. The bus master
follows the command byte with a two byte address (TA1=(T7:T0), TA2=(T15:T8)) that indicates a
starting byte location within the data field. With every subsequent read data time slot the bus master
receives data from the DS1985 starting at the initial address and continuing until the end of the 16384-bits
data field is reached or until a Reset Pulse is issued. If reading occurs through the end of memory space,
the bus master may issue sixteen additional read time slots and the DS1985 will respond with a 16-bit
CRC of the command, address bytes and all data bytes read from the initial starting byte through the last
byte of memory. This CRC is the result of clearing the CRC generator and then shifting in the command
byte followed by the two address bytes and the data bytes beginning at the first addressed memory
location and continuing through to the last byte of the EPROM data memory. After the CRC is received
by the bus master, any subsequent read time slots will appear as logical 1s until a Reset Pulse is issued.
Any reads ended by a Reset Pulse prior to reaching the end of memory will not have the 16-bit CRC
available.
Typically a 16-bit CRC would be stored with each page of data to ensure rapid, error-free data transfers
that eliminate having to read a page multiple times to determine if the received data is correct or not. (See
Book of DS19xx iButton Standards, Chapter 7 for the recommended file structure to be used with the 1-
Wire environment.) If CRC values are imbedded within the data, a Reset Pulse may be issued at the end
of memory space during a Read Memory command.
相關(guān)PDF資料
PDF描述
DS1985-F5 16-kbit Add-Only iButton
DS1985-F3 16-kbit Add-Only iButton
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS1985+F3 制造商:Maxim Integrated Products 功能描述:ADD-O IBTN 16KB, F3 (GENERIC) LFREE - Rail/Tube
DS1985+F5 制造商:Maxim Integrated Products 功能描述:ADD-O IBTN 16KB, F5 (GENERIC) LFREE - Rail/Tube
DS1985-F3 功能描述:iButton RoHS:否 存儲(chǔ)類型:SRAM 存儲(chǔ)容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated
DS1985-F3# 功能描述:iButton RoHS:否 存儲(chǔ)類型:SRAM 存儲(chǔ)容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated
DS1985-F3+ 功能描述:iButton 16Kb Add-Only iButton RoHS:否 存儲(chǔ)類型:SRAM 存儲(chǔ)容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated
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