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參數(shù)資料
| 型號： | FM25640 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | TERM STRIP, TH, LO PRO |
| 中文描述： | 64Kb的FRAM的串行存儲器 |
| 文件頁數(shù)： | 7/14頁 |
| 文件大?。?/td> | 131K |
| 代理商： | FM25640 |
FM25640
Rev. 2.1
Aug 2003
7 of 14
The BP1 and BP0 bits and the Write Enable Latch
are the only mechanisms that protect the memory
from writes. The remaining write protection features
protect inadvertent changes to the block protect bits.
The WPEN bit controls the effect of the hardware
/WP pin. When WPEN is low, the /WP pin is
ignored. When WPEN is high, the /WP pin controls
write access to the status register. Thus the Status
register is write protected if WPEN=1 and /WP=0.
Table 4. Write Protection
WEL
WPEN
/WP
0
X
X
1
0
X
1
1
0
1
1
1
Memory Operation
The SPI interface, with its relatively high maximum
clock frequency, highlights the fast write capability
of
the
FRAM
technology.
EEPROMs, the FM25640 can perform sequential
writes at bus speed. No page register is needed and
any number of sequential writes may be performed.
This scheme provides a write protection mechanism,
which can prevent software from writing the
memory under any circumstances. This occurs if the
BP1 and BP0 are set to 1, the WPEN bit is set to 1,
and /WP is set to 0. This occurs because the block
protect bits prevent writing memory and the /WP
signal in hardware prevents altering the block
protect bits (if WPEN is high). Therefore in this
condition, hardware must be involved in allowing a
write operation. The following table summarizes the
write protection conditions.
Protected Blocks
Protected
Protected
Protected
Protected
Unprotected Blocks
Protected
Unprotected
Unprotected
Unprotected
Status Register
Protected
Unprotected
Protected
Unprotected
Unlike
SPI-bus
Write Operation
All writes to the memory array begin with a WREN
op-code. The next op-code is the WRITE instruction.
This op-code is followed by a two-byte address
value. The upper 3-bits of the address are don’t care.
In total, the 13-bits specify the address of the first
byte of the write operation. Subsequent bytes are data
and they are written sequentially. Addresses are
incremented internally as long as the bus master
continues to issue clocks. If the last address of 1FFFh
is reached, the counter will roll over to 0000h. Data is
written MSB first.
Unlike EEPROMs, any number of bytes can be
written sequentially and each byte is written to
memory immediately after it is clocked in (after the
8
th
clock). The rising edge of /CS terminates a
WRITE op-code operation.
Read Operation
After the falling edge of /CS, the bus master can issue
a READ op-code. Following this instruction is a two-
byte address value. The upper 3-bits of the address
are don’t care. In total, the 13-bits specify the address
of the first byte of the read operation. After the op-
code and address are complete, the SI line is ignored.
The bus master issues 8 clocks, with one bit read out
for each. Addresses are incremented internally as
long as the bus master continues to issue clocks. If
the last address of 1FFFh is reached, the counter will
roll over to 0000h. Data is read MSB first. The rising
edge of /CS terminates a READ op-code operation.
The bus configuration for read and write operations is
shown below.
Hold
The /HOLD pin can be used to interrupt a serial
operation without aborting it. If the bus master takes
the /HOLD pin low while SCK is low, the current
operation will pause. Taking the /HOLD pin high
while SCK is low will resume an operation. The
transitions of /HOLD must occur while SCK is low,
but the SCK pin can toggle during a hold state.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| FM25640-S | LOW PROFILE .025 SQ STRIPS |
| FM25CL04 | 4Kb FRAM Serial 3V Memory |
| FM25CL04-S | 4Kb FRAM Serial 3V Memory |
| FM25CL64 | 4Kb FRAM Serial 3V Memory |
| FM25CL64-S | 4Kb FRAM Serial 3V Memory |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| FM25640_05 | 制造商:RAMTRON 制造商全稱:RAMTRON 功能描述:64Kb FRAM Serial Memory |
| FM25640_07 | 制造商:RAMTRON 制造商全稱:RAMTRON 功能描述:64Kb FRAM Serial Memory |
| FM25640B | 制造商:RAMTRON 制造商全稱:RAMTRON 功能描述:64Kb Serial 5V F-RAM Memory |
| FM25640B_13 | 制造商:CYPRESS 制造商全稱:Cypress Semiconductor 功能描述:64Kb Serial 5V F-RAM Memory |
| FM25640B-G | 功能描述:F-RAM 64Kb Serial SPI 5V FRAM RoHS:否 存儲容量:512 Kbit 組織:64 K x 8 接口:SPI 工作電源電壓:2 V to 3.6 V 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube 制造商:Cypress Semiconductor |
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