Scrub/Refresh Register - Motorola MVME2400 Series Programmer's Reference Manual

Scrub/Refresh Register

Address
$FEF80040
Bit
Name
Operation
Reset
scb0,scb1 These bits increment every time the scrubber completes a
scrub of the entire SDRAM. When they reach binary 11, they roll over
to binary 00 and continue. These bits are cleared by power-up reset.
swen When set, swen allows the scrubber to perform write cycles.
When cleared, swen prevents scrubber writes.
SCRUB_FREQUENCY Determines the rate of scrubbing by setting
the roll-over count for the scrub prescale counter. Each time the SMC
performs a refresh burst, the scrub prescale counter increments by one.
When the scrub prescale counter reaches the value stored in this
register, it clears and resumes counting starting at 0.
Note that when this register is all 0's, the scrub prescale counter does
not increment, disabling any scrubs from occurring. Since
SCRUB_FREQUENCY is cleared to 0's at power-up reset, scrubbing
is disabled until software programs a non-zero value into it.
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READ ZERO READ ZERO
X X
Programming Model
SCRUB
FREQUENCY
READ/WRITE
$00 P
3-51
3