3.3V MULTI-QUEUE FLOW-CONTROL DEVICES
(4 QUEUES) 36 BIT WIDE CONFIGURATION
589,824 bits
1,179,648 bits
2,359,296 bits
IDT72V51236
IDT72V51246
IDT72V51256
FEATURES:
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Choose from among the following memory density options:
IDT72V51236
Total Available Memory = 589,824 bits
IDT72V51246
Total Available Memory = 1,179,648 bits
IDT72V51256
Total Available Memory = 2,359,296 bits
Configurable from 1 to 4 Queues
Queues may be configured at master reset from the pool of
Total Available Memory in blocks of 256 x 36
Independent Read and Write access per queue
User programmable via serial port
Default multi-queue device configurations
-IDT72V51236: 4,096 x 36 x 4Q
-IDT72V51246: 8,192 x 36 x 4Q
-IDT72V51256: 16,384 x 36 x 4Q
100% Bus Utilization, Read and Write on every clock cycle
166 MHz High speed operation (6ns cycle time)
3.7ns access time
Individual, Active queue flags (OV,
FF, PAE, PAF, PR)
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4 bit parallel flag status on both read and write ports
Provides continuous
PAE
and
PAF
status of up to 4 Queues
Global Bus Matching - (All Queues have same Input Bus Width
and Output Bus Width)
User Selectable Bus Matching Options:
- x36in to x36out
- x18in to x36out
- x9in to x36out
- x36in to x18out
- x36in to x9out
FWFT mode of operation on read port
Packet mode operation
Partial Reset, clears data in single Queue
Expansion of up to 8 multi-queue devices in parallel is available
JTAG Functionality (Boundary Scan)
Available in a 256-pin PBGA, 1mm pitch, 17mm x 17mm
HIGH Performance submicron CMOS technology
Industrial temperature range (-40°C to +85°C) is available
FUNCTIONAL BLOCK DIAGRAM
MULTI-QUEUE FLOW-CONTROL DEVICE
WRITE CONTROL
READ CONTROL
WADEN
FSTR
WRADD
WEN
WCLK
5
RADEN
ESTR
6
Q
0
RDADD
REN
RCLK
OE
x9, x18, x36
DATA IN
Din
Qout
x9, x18, x36
DATA OUT
WRITE FLAGS
READ FLAGS
FF
PAF
PAFn
4
Q
3
OV
PR
PAE
4
PAEn/PRn
5937 drw01
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
1
2003
Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
JUNE 2003
DSC-5937/9
IDT72V51236/72V51246/72V51256 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(4 QUEUES) 36 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
DESCRIPTION:
The IDT72V51236/72V51246/72V51256 multi-queue flow-control de-
vices are single chip within which anywhere between 1 and 4 discrete FIFO
queues can be setup. All queues within the device have a common data input
bus, (write port) and a common data output bus, (read port). Data written into
the write port is directed to a respective queue via an internal de-multiplex
operation, addressed by the user. Data read from the read port is accessed
from a respective queue via an internal multiplex operation, addressed by
the user. Data writes and reads can be performed at high speeds up to
166MHz, with access times of 3.7ns. Data write and read operations are totally
independent of each other, a queue maybe selected on the write port and
a different queue on the read port or both ports may select the same queue
simultaneously.
The device provides Full flag and Output Valid flag status for the queue
selected for write and read operations respectively. Also a Programmable
Almost Full and Programmable Almost Empty flag for each queue is provided.
Two 4 bit programmable flag busses are available, providing status of all
queues, including queues not selected for write or read operations, these flag
busses provide an individual flag per queue.
Bus Matching is available on this device, either port can be 9 bits, 18 bits
or 36 bits wide provided that at least one port is 36 bits wide. When Bus
Matching is used the device ensures the logical transfer of data throughput
in a Little Endian manner.
A packet mode of operation is also provided when the device is configured
for 36 bit input and 36 bit output port sizes. The Packet mode provides the user
with a flag output indicating when at least one (or more) packets of data within a
queue is available for reading. The Packet Ready provides the user with a means
by which to mark the start and end of packets of data being passed through the
queues. The multi-queue device then provides the user with an internally
generated packet ready status per queue.
The user has full flexibility configuring queues within the device, being able
to program the total number of queues between 1 and 4, the individual queue
depths being independent of each other. The programmable flag positions are
also user programmable. All programming is done via a dedicated serial port.
If the user does not wish to program the multi-queue device, a default option is
available that configures the device in a predetermined manner.
Both Master Reset and Partial Reset pins are provided on this device. A Master
Reset latches in all configuration setup pins and must be performed before
programming of the device can take place. A Partial Reset will reset the read and
write pointers of an individual queue, provided that the queue is selected on both
the write port and read port at the time of partial reset.
A JTAG test port is provided, here the multi-queue flow-control device has a
fully functional Boundary Scan feature, compliant with IEEE 1149.1 Standard
Test Access Port and Boundary Scan Architecture.
See Figure 1,
Multi-Queue Flow-Control Device Block Diagram
for an outline
of the functional blocks within the device.
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IDT72V51236/72V51246/72V51256 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(4 QUEUES) 36 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
DETAILED DESCRIPTION
MULTI-QUEUE STRUCTURE
The IDT multi-queue flow-control device has a single data input port and
single data output port with up to 4 FIFO queues in parallel buffering between
the two ports. The user can setup between 1 and 4 Queues within the device.
These queues can be configured to utilize the total available memory, providing
the user with full flexibility and ability to configure the queues to be various depths,
independent of one another.
MEMORY ORGANIZATION/ ALLOCATION
The memory is organized into what is known as “blocks”, each block being
256 x36 bits. When the user is configuring the number of queues and individual
queue sizes the user must allocate the memory to respective queues, in units
of blocks, that is, a single queue can be made up from 0 to m blocks, where m
is the total number of blocks available within a device. Also the total size of any
given queue must be in increments of 256 x36. For the IDT72V51236/
72V51246 and IDT72V51256 the Total Available Memory is 64, 128 and 256
blocks respectively (a block being 256 x36). Queues can be built from these
blocks to make any size queue desired and any number of queues desired.
BUS WIDTHS
The input port is common to all queues within the device, as is the output port.
The device provides the user with Bus Matching options such that the input port
and output port can be either x9, x18 or x36 bits wide provided that at least one
of the ports is x36 bits wide, the read and write port widths being set
independently of one another. Because the ports are common to all queues the
width of the queues is not individually set, so that the input width of all queues
are equal and the output width of all queues are equal.
WRITING TO & READING FROM THE MULTI-QUEUE
Data being written into the device via the input port is directed to a discrete
queue via the write queue select address inputs. Conversely, data being read
from the device read port is read from a queue selected via the read queue select
address inputs. Data can be simultaneously written into and read from the same
queue or different queues. Once a queue is selected for data writes or reads,
the writing and reading operation is performed in the same manner as
conventional IDT synchronous FIFO, utilizing clocks and enables, there is a
single clock and enable per port. When a specific queue is addressed on the
write port, data placed on the data inputs is written to that queue sequentially
based on the rising edge of a write clock provided setup and hold times are met.
Conversely, data is read on to the output port after an access time from a rising
edge on a read clock.
The operation of the write port is comparable to the function of a conventional
FIFO operating in standard IDT mode. Write operations can be performed on
the write port provided that the queue currently selected is not full, a full flag output
provides status of the selected queue. The operation of the read port is
comparable to the function of a conventional FIFO operating in FWFT mode.
When a queue is selected on the output port, the next word in that queue will
automatically fall through to the output register. All subsequent words from that
queue require an enabled read cycle. Data cannot be read from a selected
queue if that queue is empty, the read port provides an Output Valid flag indicating
when data read out is valid. If the user switches to a queue that is empty, the
last word from the previous queue will remain on the output register.
As mentioned, the write port has a full flag, providing full status of the selected
queue. Along with the full flag a dedicated almost full flag is provided, this almost
full flag is similar to the almost full flag of a conventional IDT FIFO. The device
5
provides a user programmable almost full flag for all 4 queues and when a
respective queue is selected on the write port, the almost full flag provides status
for that queue. Conversely, the read port has an output valid flag, providing
status of the data being read from the queue selected on the read port. As well
as the output valid flag the device provides a dedicated almost empty flag. This
almost empty flag is similar to the almost empty flag of a conventional IDT FIFO.
The device provides a user programmable almost empty flag for all 4 queues
and when a respective queue is selected on the read port, the almost empty flag
provides status for that queue.
PROGRAMMABLE FLAG BUSSES
In addition to these dedicated flags, full & almost full on the write port and output
valid & almost empty on the read port, there are two flag status busses. An almost
full flag status bus is provided, this bus is 4 bits wide. Also, an almost empty flag
status bus is provided, again this bus is 4 bits wide. The purpose of these flag
busses is to provide the user with a means by which to monitor the data levels
within queues that may not be selected on the write or read port. As mentioned,
the device provides almost full and almost empty registers (programmable by
the user) for each of the 4 queues in the device.
The 4 bit
PAEn
and 4 bit
PAFn
busses provide a discrete status of the Almost
Empty and Almost Full conditions of all 4 queue's. If the device is programmed
for less than 4 queue's, then there will be a corresponding number of active
outputs on the
PAEn
and
PAFn
busses.
The flag busses can provide a continuous status of all queues. If devices are
connected in expansion mode the individual flag busses can be left in a discrete
form, providing constant status of all queues, or the busses of individual devices
can be connected together to produce a single bus of 4 bits. The device can
then operate in a "Polled" or "Direct" mode.
When operating in polled mode the flag bus provides status of each device
sequentially, that is, on each rising edge of a clock the flag bus is updated to show
the status of each device in order. The rising edge of the write clock will update
the Almost Full bus and a rising edge on the read clock will update the Almost
Empty bus.
When operating in direct mode the device driving the flag bus is selected by
the user. The user addresses the device that will take control of a respective
flag bus, these
PAFn
and
PAEn
flag busses operating independently of one
another. Addressing of the Almost Full flag bus is done via the write port and
addressing of the Almost Empty flag bus is done via the read port.
PACKET MODE
The multi-queue flow-control device also offers a “Packet Mode” operation.
Packet Mode is user selectable and requires the device to be configured with
both write and read ports as 36 bits wide. In packet mode, users can define
the length of packets or frame by using the two most significant bits of the 36-
bit word. Bit 34 is used to mark the Start of Packet (SOP) and bit 35 is used to
mark the End of Packet (EOP) as shown in Table 5). When writing data into
a given queue, the first word being written is marked, by the user setting bit 34
as the “Start of Packet” (SOP) and the last word written is marked as the “End
of Packet” (EOP) with all words written between the Start of Packet (SOP)
marker (bit 34) and the End of packet (EOP) packet marker (bit 35) constituting
the entire packet. A packet can be any length the user desires, up to the total
available memory in the multi-queue flow-control device. The device monitors
the SOP (bit 34) and looks for the word that contains the EOP (bit 35). The read
port is supplied with an additional status flag, “Packet Ready”. The Packet
Ready (PR) flag in conjunction with Output Valid (OV) indicates when at least
one packet is available to read. When in packet mode the almost empty flag
status, provides packet ready flag status for individual queues.
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