MPC8280 datasheet(442/1386 Pages) FREESCALE

442 / 1386 page

Memory Controller

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

11-22

Freescale Semiconductor

SDRAM Device–Specific Parameters:

14–16

RFRC

Refresh recovery. Defines the earliest timing for an activate command after a REFRESH

command. Sets the refresh recovery interval in clock cycles. See Section 11.4.6.6, “Refresh

Recovery Interval (RFRC),” for how to set this field.

000 Reserved

001 3 clocks

010 4 clocks

011 5 clocks

100 6 clocks

101 7 clocks

110 8 clocks

111 16 clocks

17–19 PRETOACT Precharge to activate interval. Defines the earliest timing for ACTIVATE or REFRESH command

after a precharge command. See Section 11.4.6.1, “Precharge-to-Activate Interval.”

001 1 clock-cycle wait states

010 2 clock-cycle wait states

...

111 7 clock-cycle wait states

000 8 clock-cycle wait states

20–22

ACTTORW

Activate to read/write interval. Defines the earliest timing for READ/WRITE command after an

ACTIVATE

command. See Section 11.4.6.2, “Activate to Read/Write Interval.”

001 1 clock cycle

010 2 clock cycles

...

111 7 clock cycles

000 8 clock cycles

Burst length

0 SDRAM burst length is 4. Use this value if the device port size is 64 or 16

1 SDRAM burst length is 8. Use this value if the device port size is 32 or 8

24–25 LDOTOPRE Last data out to precharge. Defines the earliest timing for PRECHARGE command after the last

data was read from the SDRAM. See Section 11.4.6.4, “Last Data Out to Precharge.”

00 0 clock cycles

01 -1 clock cycle

10 -2 clock cycles

11 Reserved

Note: A value of 0b00 (0 clock cycles) gives the longest time while a value of 0b10 (-2 clock

cycles) gives the least.

26–27

WRC

Write recovery time. Defines the earliest timing for PRECHARGE command after the last data was

written to the SDRAM. See Section 11.4.6.5, “Last Data In to Precharge—Write Recovery.”

01 1 clock cycles

10 2 clock cycles

11 3 clock cycles

00 4 clock cycles

Table 11-8. PSDMR Field Descriptions (continued)

Bits

Name

Description

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