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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)： | 5/24頁 |
| 文件大?。?/td> | 164K |
| 代理商： | DS1986 |
DS1986
052298 5/24
65536–BITS EPROM
The memory map in Figure 4 shows the 65536–bit
EPROM section of the DS1986 which is configured as
256 pages of 32 bytes each. The 8–bit scratchpad is an
additional register that acts as a buffer when program-
ming the memory. Data is first written to the scratchpad
and then verified by reading an 16–bit CRC from the
DS1986 that confirms proper receipt of the data and
address. If the buffer contents are correct, a program-
ming voltage should be applied and the byte of data will
be written into the selected address in memory. This
process insures data integrity when programming the
memory. The details for reading and programming the
65536–bit EPROM portion of the DS1986 are given in
the Memory Function Commands section.
EPROM STATUS BYTES
In addition to the 65536 bits of data memory the DS1986
provides 2816 bits of Status Memory accessible with
separate commands.
The EPROM Status Bytes can be read or programmed
to indicate various conditions to the software interrogat-
ing the DS1986. The first 32 bytes of the EPROM Status
Memory (addresses 000 to 01FH) contain the Write Pro-
tect Page bits which inhibit programming of the corre-
sponding page in the 65536–bit main memory area if the
appropriate write protection bit is programmed. Once a
bit has been programmed in the Write Protect Page sec-
tion of the Status Memory, the entire 32 byte page that
corresponds to that bit can no longer be altered but may
still be read.
The next 32 bytes of the EPROM Status Memory
(addresses 020 to 03FH) contain the Write Protect bits
which inhibit altering the Page Address Redirection
Byte corresponding to each page in the 65536–bit main
memory area.
The following 32 bytes within the EPROM Status
Memory (addresses 040 to 05FH) are reserved for use
by the iButton operating software TMEX. Their purpose
is to indicate which memory pages are already in use.
Originally, all of these bits are unprogrammed, indicat-
ing that the device does not store any data. As soon as
data is written to any page of the device under control of
TMEX, the bit inside this bitmap corresponding to that
page will be programmed to 0, marking this page as
used. These bits are application flags only and have no
impact on the internal logic of the DS1986.
The next 256 bytes of the EPROM Status Memory
(addresses 100H to 1FFH) contain the Page Address
Redirection Bytes which indicate if one or more of the
pages of data in the 65536–bit EPROM section have
been invalidated by software and redirected to the page
address contained in the appropriate redirection byte.
The hardware of the DS1986 makes no decisions based
on the contents of the Page Address Redirection Bytes.
Since with EPROM technology bits can only be
changed from a logical 1 to a logical 0 by programming,
it is not possible to simply rewrite a page if the data
requires changing or updating. But with space permit-
ting, an entire page of data can be redirected to another
page within the DS1986. Under TMEX a page is redi-
rected by writing the one’s complement of the new page
address into the Page Address Redirection Byte that
corresponds to the original (replaced) page. This archi-
tecture allows the user’s software to make a “data
patch” to the EPROM by indicating that a particular page
or pages should be replaced with those indicated in the
Page Address Redirection Bytes. To leave an authentic
audit trail of data patches, it is recommended to also
program the write protect bit of the Page Address
Redirection Byte, after the page redirection is pro-
grammed. Without this protection, it is still possible to
modify the Page Address Redirection Byte, making it
point to a different memory page than the true one.
If a Page Address Redirection Byte has a FFH value, the
data in the main memory that corresponds to that page
is valid. If a Page Address Redirection Byte has some
other hex value than FFH, the data in the page corre-
sponding to that redirection byte is invalid. According to
the TMEX definitions the valid data can now be found at
the one’s complement of the page address indicated by
the hex value stored in the associated Page Address
Redirection Byte. A value of FDH in the redirection byte
for page 1, for example, would indicate that the updated
data is now in page 2. The status memory is pro-
grammed similarly to the data memory. Details for read-
ing and programming the EPROM status memory por-
tion of the DS1986 are given in the Memory Function
Commands section.
The Status Memory address range of the DS1986
extends from 000 to 1FFH. The memory locations 60H
to 0FFH and 200H and higher are physically not imple-
mented. Reading these locations will usually result in
FFH bytes. Attempts to write to these locations will be
ignored.
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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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