
Section 3
Hardware Architecture PLX Option Module Connector
3.4 Synchronous Dual-Port RAM
(DPRAM)
The PCI 9030 is connected to (2) two
Synchronous Dual–Port RAMs, U11 and U12,
on the RDK board. These DPRAMs are 3.3V, 9
ns, 4Kx18 Cypress devices. However, the board
is assembled with one DPRAM (U11) on board
as a default.
The DPRAM serves two purposes on the RDK
board. First, the left port of DPRAM U11,
connects to the lower 16-bit data bus of the PCI
9030 with simple interface logic that resides in
the 5ns, 20-pin programmable GAL device. A
PCI bus master can perform 8- and 16-bit single
memory cycles with the DPRAM through the PCI
9030. If the PCI bus master supports bursting,
the PCI master can perform 16-bit continuous
burst memory cycles with the DPRAM also.
Second, the PCI 9030 is a PCI target chip with
an output only address bus. If a customer’s
design has a microprocessor or microcontroller,
they can place these devices on the separate
bus on the right port of the DPRAM. Also, if the
customer wants to have 32-bit DPRAM, they can
add the same Cypress chip to U12 and
rearrange the resistor networks RN34, RN36
and RN38. (See page 5 of the Schematics for
more details.)
The interface between the PCI 9030 and the
DPRAMs is very straightforward. The left port of
the DPRAM is configured in the pipelined mode.
Three control input signals, chip enable 1
(CE1L), counter enable (CNTENLL), and output
enable (OELL) are enabled and the counter
reset signal (CNTRSTL) is disabled with related
pull-up and pull-down resistors. Only two control
input signals, address strobe (ADSLL) and chip
enable (CE0L), are converted from PCI 9030
control signals. If the PCI 9030 local clock is
running at 60MHz, the PCI 9030 needs two wait
states for the single or the first data read of a
burst memory read cycle, and zero wait states
for the single or burst write cycle.
On the right port of the DPRAMs, all the input
control signals are preset to idle states. A 29x2
header, J3, provides access to address, data,
and control signals on the right port and nearby
prototyping pads provide the connections to the
customers’ designs in the separate bus on the
right port of the DPRAMs.
3.5 Hot Swap Control Circuit
The RDK is a full Hot Swap board that includes
both hardware connection control and software
connection control in accordance with the
CompactPCI Hot Swap specifications. It can
work on a range of systems from non-Hot Swap
systems to High Availability systems.
3.5.1 Hardware Connection Control
The BD_SEL# signal at the J1 CompactPCI
connector is connected to the BD_SELL input of
PCI 9030 chip and ON# signal input of the
Linear Technology LTC1643L Hot Swap
Controller. An external 1.2K ohm pull-up resistor
is connected to this signal pin and early VIO
power. When the board is hot plugged into a
CompactPCI system, before the J1 connector
makes contact with the BD_SEL# pin on the
backplane, the PCI 9030 chip is already
powered-up with early 3.3V. The 1.2K-ohm
external pull-up will activate the PCI 9030
internal pre-charge regulator and built-in 10K
ohm pull-up resistors to precharge all required
PCI I/O signals on the RDK to one Volt. This
prevents erroneous system operation during Hot
Swap insertion of the board.
The Board Healthy signal, HEALTHYL, is
generated by the LTC1643L as the Power Good
signal for the 5V power output. The Power-Good
Threshold voltage is 4.40 to 4.75V. As long as
the 5V power input reaches this range, the
Power-Good signal – HEALTHYL—will be
generated. Also the LTC1643L controls the
current limit and the power up rate. In this RDK,
the current limit is 3A (the capacity of the LDO of
the LT1587CM-3.3) and the power up rate would
be dv/dt = 50uA/0.1uF, or determined by the
current limit and the load capacitance,
whichever is slower.
With two logic gates, the Local PCI Reset signal,
LOCAL_RSRL, was driven from the Platform
Reset, PCIRSTL, from the system backplane
and the Healthy signal, HEALTHYL from the
LTC1643L to reset the PCI 9030.
3.5.2 Software Connection Control
A micro switch located at the lower ejector
handle of the 6U RDK board is used to signal
the insertion or impending extraction of the RDK.
When the handle is unlocked, the CPCISW is
pulled-up to 3.3V. That informs the PCI 9030
that the board is at the impending extraction
state. When the handle is locked, CPCISW is
CompactPCI 9030RDK-LITE Hardware Reference Manual v1.2
10 © 2004 PLX Technology, Inc. All rights reserved.