Motorola ColdFire MCF5281 - Manual (Page 285)

Synchronous DRAM Controller Module
Freescale Semiconductor 15-13
15.2.3.2 SDRAM Byte Strobe Connections
Figure 15-5 shows SDRAM connections for port sizes of 32, 16, or 8 bits.
Figure 15-5. Connections for External Memory Port Sizes
15.2.3.3 Interfacing Example
The tables in the previous section can be used to configure the interface in the following example. To
interface one 2M x 32-bit x 4 bank SDRAM component (8 columns), use the connections shown in
Table 15-24 .
15.2.3.4 Burst Page Mode
SDRAM can efficiently provide data when an SDRAM page is opened. As soon as SCAS is issued, the
SDRAM accepts a new address and asserts SCAS every CLKOUT for as long as accesses occur in that
page. In burst page mode, there are multiple read or write operations for every
ACTV command in the
SDRAM if the requested transfer size exceeds the port size of the associated SDRAM. The primary cycle
of the transfer generates the
ACTV and READ or WRITE commands; secondary cycles generate only READ
or WRITE commands. As soon as the transfer completes, the PALL command is generated to prepare for the
next access.
Table 15-23. Processor to SDRAM Interface (32-Bit Port, 12-Column Address Lines)
Processor
Pins A15 A14 A13 A12 A11 A10 A9 A17 A19 A21 A23
Row 15 14 13 12 11 10 9 17 19 21 23
Column 2 3 4 5 6 7 8 16 18 20 22
SDRAM
Pins A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10
Table 15-24. SDRAM Hardware Connections
SDRAM Pins A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 = CMD BA0 BA1
Processor Pins A15 A14 A13 A12 A11 A10 A9 A17 A18 A19 A20 A21 A22
Processor
Data Bus
Byte 0
8-Bit Port
16-Bit Port
32-Bit Port
Byte 1
Byte 2
Byte 3
Byte 0 Byte 1
Byte 2 Byte 3
Byte 0 Byte 1 Byte 2 Byte 3
D[31:24] D[23:16] D[15:8] D[7:0]
External
Memory
Memory
Memory
Byte Enable BS3 BS2 BS1 BS0
Driven with
indeterminate values
Driven with
indeterminate values
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3