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參數(shù)資料
| 型號： | 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)： | 11/24頁 |
| 文件大小： | 164K |
| 代理商： | DS1986 |
DS1986
052298 11/24
After the 16–bit CRC of the last EPROM Status data
page is read, the bus master will receive logical 1s from
the DS1986 until a Reset Pulse is issued. The Read Sta-
tus command sequence can be ended at any point by
issuing a Reset Pulse.
EXTENDED READ MEMORY [A5H]
The Extended Read Memory command supports page
redirection when reading data from the 65536–bit
EPROM data field. One major difference between the
Extended Read Memory and the basic Read Memory
command is that the bus master receives the Redirec-
tion Byte first before investing time in reading data from
the addressed memory location. This allows the bus
master to quickly decide whether to continue and
access the data at the selected starting page or to termi-
nate and restart the reading process at the redirected
page address. A non–redirected page is identified by a
Redirection Byte with a value of FFH (see description of
EPROM Status Bytes). If the Redirection Byte is differ-
ent than this, the master has to complement it to obtain
the new page number. Multiplying the page number by
32 (20H) results in the new address the master has to
send to the DS1986 to read the updated data replacing
the old data. There is no logical limitation in the number
of redirections of any page. The only limit is the number
of available memory pages within the DS1986.
In addition to page redirection, the Extended Read
Memory command also supports “bit–oriented” applica-
tions where the user cannot store a 16–bit CRC with the
data itself. With bit–oriented applications the EPROM
information may change over time within a page bound-
ary making it impossible to include an accompanying
CRC that will always be valid. Therefore, the Extended
Read Memory command concludes each page with the
DS1986 generating and supplying a 16–bit CRC that is
based on and therefore always consistent with the cur-
rent data stored in each page of the 65536–bit EPROM
data field.
After having sent the command code of the Extended
Read Memory command, 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. By sending eight read data time
slots, the master receives the Redirection Byte
associated with the page given by the starting address.
With the next sixteen read data time slots, the bus mas-
ter receives a 16–bit CRC of the command byte,
address bytes and the Redirection Byte. This CRC is
computed by the DS1986 and read back by the bus
master to check if the command word, starting address
and Redirection Byte 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. If the CRC received by the bus master is cor-
rect, the bus master issues read time slots and receives
data from the DS1986 starting at the initial address and
continuing until the end of a 32–byte page is reached. At
that point the bus master will send sixteen additional
read time slots and receive a 16–bit CRC that is the
result of shifting into the CRC generator all of the data
bytes from the initial starting byte to the last byte of the
current page.
With the next 24 read data time slots the master will
receive the Redirection Byte of the next page followed
by a 16–bit CRC of the Redirection Byte. After this, data
is again read from the 65536–bit EPROM data field
starting at the beginning of the new page. This
sequence will continue until the final page and its
accompanying CRC are read by the bus master.
The Extended Read Memory command provides a
16–bit CRC at two locations within the transaction flow
chart: 1) after the Redirection Byte and 2) at the end of
each memory page. The CRC at the end of the memory
page is always the result of clearing the CRC generator
and shifting in the data bytes beginning at the first
addressed memory location of the EPROM data page
until the last byte of this page. With the initial pass
through the Extended Read Memory flow chart the
16–bit CRC value is the result of shifting the command
byte into the cleared CRC generator, followed by the two
address bytes and the Redirection Byte. Subsequent
passes through the Extended Read Memory flow chart
will generate a 16–bit CRC that is the result of clearing
the CRC generator and then shifting in the Redirection
Byte only.
After the 16–bit CRC of the last page is read, the bus
master will receive logical 1s from the DS1986 until a
Reset Pulse is issued. The Extended Read Memory
command sequence can be exited at any point by issu-
ing a Reset Pulse.
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相關(guān)代理商/技術(shù)參數(shù) |
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| 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 存儲類型:SRAM 存儲容量: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 存儲類型:SRAM 存儲容量: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 存儲類型:SRAM 存儲容量: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 存儲類型:SRAM 存儲容量: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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