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May 25, 2004
IDT 79RC32438
WAITACKN
I
Wait or Transfer Acknowledge.
When configured as wait, this signal is
asserted during a memory and peripheral bus transaction to extend the bus
cycle. When configured as a transfer acknowledge, this signal is asserted during
a transaction to signal the completion of the transaction.
DDR Bus
DDRADDR[13:0]
O
DDR Address Bus.
14-bit multiplexed DDR bus address bus. This bus is used
to transfer the addresses to the DDR devices.
DDRBA[1:0]
O
DDR Bank Address.
These signals are used to transfer the bank address to the
DDRs.
DDRCASN
O
DDR Column Address Strobe.
This signal is asserted during DDR transac-
tions.
DDRCKE
O
DDR Clock Enable.
The DDR clock enable is asserted during normal DDR
operation. This signal is negated during following a cold reset or during a power
down operation.
DDRCKN[1:0]
O
DDR Negative DDR clock.
These signals are the negative clock of the differen-
tial DDR clock pair. Two copies of this output are provided to reduce signal load-
ing.
DDRCKP[1:0]
O
DDR Positive DDR clock.
These signals are the positive clock of the differen-
tial DDR clock pair. Two copies of this output are provided to reduce signal load-
ing.
DDRCSN[1:0]
O
DDR Chip Selects.
These active low signals are used to select DDR device(s)
on the DDR bus.
DDRDATA[31:0]
I/O
DDR Data Bus.
32-bit DDR data bus used to transfer data between the
RC32438 and the DDR devices. Data is transferred on both edges of the clock.
DDRDM[7:0]
O
DDR Data Write Enables.
Byte data write enables used to enable specific byte
lanes during DDR writes.
DDRDM[0] corresponds to DDRDATA[7:0]
DDRDM[1] corresponds to DDRDATA[15:8]
DDRDM[2] corresponds to DDRDATA[23:16]
DDRDM[3] corresponds to DDRDATA[31:24]
DDRDM[4] corresponds to DDRDATA[39:32]
DDRDM[5] corresponds to DDRDATA[47:40]
DDRDM[6] corresponds to DDRDATA[55:48]
DDRDM[7] corresponds to DDRDATA[54:56]
(Refer to the DDR Data Bus Multiplexing section in Chapter 7 of the RC32438
User Reference Manual.)
DDRDQS[3:0]
I/O
DDR Data Strobes.
DDR byte data strobes used to clock data between DDR
devices and the RC32438. These strobes are inputs during DDR reads and out-
puts during DDR writes.
DDRDQS[0] corresponds to DDRDATA[7:0].
DDRDQS[1] corresponds to DDRDATA[15:8].
DDRDQS[2] corresponds to DDRDATA[23:16].
DDRDQS[3] corresponds to DDRDATA[31:24].
DDROEN[3:0]
O
DDR Bus Switch Output Enables.
These pins are used to enable external
data bus switches in systems that support data bus multiplexing.
DDRRASN
O
DDR Row Address Strobe.
The DDR row address strobe is asserted during
DDR transactions.
Signal
Type
Name/Description
Table 1 Pin Description (Part 2 of 9)