MCF548x Reference Manual, Rev. 3
18-2 Freescale Semiconductor

18.2.3 Block Diagram

Figure 18-1. SDRAM Controller Block Diagram

18.3 External Signal Description

18.3.1 SDRAM Data Bus (SDDATA[31:0])

SDDATA[31:0] is the bidirectional, non-multiplexed data bus used for SDRAM accesses. Data is sampled

by the MCF548x on the rising edge of SDCLK when in SDR mode, and on both the rising and falling edge

of SDCLK when in DDR mode.

18.3.2 SDRAM Address Bus (SDADDR[12:0])

The SDADDR[12:0] signals are the 13-bit, uni-directional address bus used for multiplexed row and

column addresses during SDRAM bus cycles. The address multiplexing supports up to 256 Mbytes of

SDRAM per chip select.

18.3.3 SDRAM Bank Addresses (SDBA[1:0])

Each SDRAM module has four internal row banks. The SDBA[1:0] signals are used to select the row bank.

It is also used to select the SDRAM internal mode register during power-up initialization.

addr[1:3] CAS
SDWE
SDDQS
SDCLK[1:0]
SDCLK[1:0]
SDCKE
RAS
SDCS[3:0]
dataout[63:0]
SDDM
SDDATA[31:0]
SDDATA[31:0]
Row
Bank
Column
addr[29:4]
Row
Bank
Column
SDBA[1:0]
SDADDR[12:0]
Select
datain[63:0]
SDRAM
Controller
State
Machine
Read Data
Buffer
Write Data
Buffer
Address
Output
MUX
Address
Pipeline
Latches
Address
Input
MUX
tsiz[1:0], tbst