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參數(shù)資料
| 型號(hào)： | DS1986 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 64K bit Add-Only iButton(64K位只加按鈕) |
| 中文描述： | 64K位只添加iButton® |
| 文件頁數(shù)： | 7/24頁 |
| 文件大?。?/td> | 164K |
| 代理商： | DS1986 |
DS1986
052298 7/24
MEMORY FUNCTION COMMANDS
The “Memory Function Flow Chart” (Figure 5) describes
the protocols necessary for accessing the various data
fields within the DS1986. 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 three–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 12–volt programming voltage at the
appropriate times. To execute a write sequence, a byte
of data is first loaded into the scratchpad and then pro-
grammed 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 DS1986 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 65536–bits EPROM data field. The bus master fol-
lows 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 subse-
quent read data time slot the bus master receives data
from the DS1986 starting at the initial address and con-
tinuing until the end of the 65536–bits data field is
reached or until a Reset Pulse is issued. If reading
occurs through the end of memory space, the bus mas-
ter may issue sixteen additional read time slots and the
DS1986 will respond with a 16–bit CRC of the com-
mand, 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 insure rapid, error–free data transfers that
eliminate having to read a page multiple times to deter-
mine if the received data is correct or not. (See Book of
DS19xx iButton Standards, Chapter 7 for the recom-
mended file structure to be used with the 1–Wire envi-
ronment.) 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.
READ STATUS [AAH]
The Read Status command is used to read data from
the EPROM Status 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 subse-
quent read data time slot the bus master receives data
from the DS1986 starting at the supplied address and
continuing until the end of an eight–byte page of the
EPROM Status data field is reached. At that point the
bus master will receive a 16–bit CRC of the command
byte, address bytes and status data bytes. This CRC is
computed by the DS1986 and read back by the bus
master to check if the command word, starting address
and data were received correctly. If the CRC read by the
bus master is incorrect, a Reset Pulse must be issued
and the entire sequence must be repeated.
Note that the initial pass through the Read Status flow
chart will generate a 16–bit CRC value that is the result
of clearing the CRC generator and then shifting in the
command byte followed by the two address bytes, and
finally the data bytes beginning at the first addressed
memory location and continuing through to the last byte
of the addressed EPROM Status data page. The last
byte of a Status data page always has an ending
address of xx7 or xxFH. Subsequent passes through
the Read Status flow chart will generate a 16–bit CRC
that is the result of clearing the CRC generator and then
shifting in the new data bytes starting at the first byte of
the next page of the EPROM Status data field.
This feature is provided since the EPROM Status
information may change over time making it impossible
to program the data once and include an accompanying
CRC that will always be valid. Therefore, the Read Sta-
tus command supplies a 16–bit CRC that is based on
and always is consistent with the current data stored in
the EPROM Status data field.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS1986+F3 | 制造商:Maxim Integrated Products 功能描述:ADD-O IBTN 64KB, F3 (GENERIC) LFREE - Rail/Tube |
| DS19860-F3-W | 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 |
| DS1986-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 |
| DS1986-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 |
| DS1986-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 |
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