CY7C008V-15AC Cypress Semiconductor Corp, CY7C008V-15AC Datasheet - Page 14
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CY7C008V-15AC
Manufacturer Part Number
CY7C008V-15AC
Description
IC SRAM 512KBIT 15NS 100LQFP
Manufacturer
Cypress Semiconductor Corp
Datasheet
1.CY7C008V-15AC.pdf
(18 pages)
Specifications of CY7C008V-15AC
Format - Memory
RAM
Memory Type
SRAM - Dual Port, Asynchronous
Memory Size
512K (64K x 8)
Speed
15ns
Interface
Parallel
Voltage - Supply
3 V ~ 3.6 V
Operating Temperature
0°C ~ 70°C
Package / Case
100-LQFP
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
428-1147
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
CY7C008V-15AC
Manufacturer:
CY
Quantity:
14
Company:
Part Number:
CY7C008V-15AC
Manufacturer:
TI
Quantity:
227
Company:
Part Number:
CY7C008V-15AC
Manufacturer:
CYPRESS
Quantity:
210
Part Number:
CY7C008V-15AC
Manufacturer:
CYPRESS/赛普拉斯
Quantity:
20 000
Architecture
The CY7C008V/009V and CY7018V/019V consist of an array
of 64K and 128K words of 8 and 9 bits each of dual-port RAM
cells, I/O and address lines, and control signals (CE, OE, R/W).
These control pins permit independent access for reads or writes to
any location in memory. To handle simultaneous writes/reads to the
same location, a BUSY pin is provided on each port. Two interrupt
(INT) pins can be utilized for port-to-port communication. Two sema-
phore (SEM) control pins are used for allocating shared resources.
With the M/S pin, the devices can function as a master (BUSY pins
are outputs) or as a slave (BUSY pins are inputs). The devices also
have an automatic power-down feature controlled by CE. Each port
is provided with its own output enable control (OE), which allows data
to be read from the device.
Functional Description
Write Operation
Data must be set up for a duration of t
of R/W in order to guarantee a valid write. A write operation is con-
trolled by either the R/W pin (see Write Cycle No. 1 waveform) or the
CE pin (see Write Cycle No. 2 waveform). Required inputs for
non-contention operations are summarized in Table 1.
If a location is being written to by one port and the opposite
port attempts to read that location, a port-to-port flowthrough
delay must occur before the data is read on the output; other-
wise the data read is not deterministic. Data will be valid on the
port t
Read Operation
When reading the device, the user must assert both the OE
and CE pins. Data will be available t
asserted. If the user wishes to access a semaphore flag, then the
SEM pin must be asserted instead of the CE pin, and OE must also
be asserted.
Interrupts
The upper two memory locations may be used for message
passing. The highest memory location (FFFF for the
CY7C008/18, 1FFFF for the CY7C009/19) is the mailbox for
the right port and the second-highest memory location (FFFE
for the CY7C008/18, 1FFFE for the CY7C009/19) is the mail-
box for the left port. When one port writes to the other port’s
mailbox, an interrupt is generated to the owner. The interrupt
is reset when the owner reads the contents of the mailbox. The
message is user defined.
Each port can read the other port’s mailbox without resetting
the interrupt. The active state of the busy signal (to a port)
prevents the port from setting the interrupt to the winning port.
Also, an active busy to a port prevents that port from reading
its own mailbox and, thus, resetting the interrupt to it.
If an application does not require message passing, do not
connect the interrupt pin to the processor’s interrupt request
input pin.
The operation of the interrupts and their interaction with Busy
are summarized in Table 2.
Busy
The CY7C008V/009V and CY7018V/019V provide on-chip ar-
bitration to resolve simultaneous memory location access
Document #: 38-06044 Rev. *B
DDD
after the data is presented on the other port.
ACE
after CE or t
SD
before the rising edge
DOE
after OE is
(contention). If both ports’ CEs are asserted and an address
match occurs within t
which port has access. If t
permission to the location, but it is not predictable which port will get
that permission. BUSY will be asserted t
or t
Master/Slave
A M/S pin is provided in order to expand the word width by configur-
ing the device as either a master or a slave. The BUSY output of the
master is connected to the BUSY input of the slave. This will allow the
device to interface to a master device with no external components.
Writing to slave devices must be delayed until after the BUSY input
has settled (t
cycle during a contention situation. When tied HIGH, the M/S pin al-
lows the device to be used as a master and, therefore, the BUSY line
is an output. BUSY can then be used to send the arbitration outcome
to a slave.
Semaphore Operation
The CY7C008V/009V and CY7018V/019V provide eight
semaphore latches, which are separate from the dual-port
memory locations. Semaphores are used to reserve resources
that are shared between the two ports.The state of the sema-
phore indicates that a resource is in use. For example, if the
left port wants to request a given resource, it sets a latch by
writing a zero to a semaphore location. The left port then ver-
ifies its success in setting the latch by reading it. After writing
to the semaphore, SEM or OE must be deasserted for t
attempting to read the semaphore. The semaphore value will be
available t
If the left port was successful (reads a zero), it assumes control of the
shared resource, otherwise (reads a one) it assumes the right port
has control and continues to poll the semaphore. When the right side
has relinquished control of the semaphore (by writing a one), the left
side will succeed in gaining control of the semaphore. If the left side
no longer requires the semaphore, a one is written to cancel its re-
quest.
Semaphores are accessed by asserting SEM LOW. The SEM
pin functions as a chip select for the semaphore latches (CE must
remain HIGH during SEM LOW). A
address. OE and R/W are used in the same manner as a normal
memory access. When writing or reading a semaphore, the other
address pins have no effect.
When writing to the semaphore, only I/O
written to the left port of an available semaphore, a one will appear at
the same semaphore address on the right port. That semaphore can
now only be modified by the side showing zero (the left port in this
case). If the left port now relinquishes control by writing a one to the
semaphore, the semaphore will be set to one for both sides. Howev-
er, if the right port had requested the semaphore (written a zero) while
the left port had control, the right port would immediately own the
semaphore as soon as the left port released it. Table 3 shows sample
semaphore operations.
When reading a semaphore, all data lines output the sema-
phore value. The read value is latched in an output register to
prevent the semaphore from changing state during a write
from the other port. If both ports attempt to access the sema-
phore within t
obtained by one side or the other, but there is no guarantee which side
will control the semaphore.
BLC
after CE is taken LOW.
SWRD
BLC
SPS
+ t
or t
DOE
BLA
of each other, the semaphore will definitely be
PS
), otherwise, the slave chip may begin a write
after the rising edge of the semaphore write.
of each other, the busy logic will determine
PS
is violated, one port will definitely gain
CY7C008V/009V
CY7C018V/019V
0–2
BLA
represents the semaphore
after an address match
0
is used. If a zero is
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SOP
before