Motorola MCF5282, MCF5281 Sdram Interface Configuration, DCR Initialization, Dacr Initialization

SDRAM Example

15.3.1 SDRAM Interface Configuration

To interface this component to the MCF5282 DRAM controller, use the connection table that corresponds to a 32-bit port size with 8 columns (Table 15-24). Two pins select one of four banks when the part is functional. Table 15-26shows the proper hardware connections.

Table 15-26. SDRAM Hardware Connections

MCF5282

A15

A14

A13

A12

A11

A10

A9

A17

A18

A19

A20

A21

A22

Pins

SDRAM Pins

A0

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10 = CMD

BA0

BA1

15.3.2 DCR Initialization

At power-up, the DCR has the following configuration if synchronous operation and SDRAM address multiplexing are desired.

15		14	13	12	11	10	9	8	0
Field	—	—	NAM	COC	IS	RTIM			RC
Setting							0000_0000_0010_0110
(hex)								0026

Figure 15-11. Initialization Values for DCR

This configuration results in a value of 0x0026 for DCR, as shown in Table 15-27.

			Table 15-27. DCR Initialization Values
Bits	Name	Setting	Description
15	—	0	Reserved.
14	—	0	Reserved.
13	NAM	0	Indicating SDRAM controller multiplexes address lines internally
12	COC	0	SCKE is used as clock enable instead of command bit because user is not multiplexing address lines
			externally and requires external command feed.
11	IS	0	At power-up, allowing power self-refresh state is not appropriate because registers are being set up.
10–9	RTIM	00	Because tRC value is 70 ns, indicating a 3-clock refresh-to-ACTVtiming.
8–0	RC	0x26	Specification indicates auto-refresh period for 4096 rows to be 64 mS or refresh every 15.625 µs for
			each row, or 625 bus clocks at 40 MHz. Because DCR[RC] is incremented by 1 and multiplied by 16,
			RC = (625 bus clocks/16) -1 = 38.06 = 0x38

15.3.3 DACR Initialization

As shown in Figure 15-12,the SDRAM is programmed to access only the second 512-Kbyte block of each 1-Mbyte partition in the SDRAM (each 16 Mbytes). The starting address of the SDRAM is 0xFF88_0000. Continuous page mode feature is used.

15-20 MCF5282 User’s Manual MOTOROLA