MMC2107 Datasheet, PDF (512/618 Pages) –

Freescale Semiconductor, Inc.
External Bus Interface Module (EBI)
19.7.1.1 State 1 (X1)
The EBI drives the address bus. R/W is driven high to indicate a read
cycle. The TSIZ[1:0] pins are driven to indicate the number of bytes in
the transfer. TC[2:0] pins are driven to indicate the type of access. CS
may be asserted to drive a device.
Later in state 1, OE is asserted. If the EB pins are not configured as write
enables for this cycle, one or more EB pins are also asserted, depending
on the size and position of the data to be transferred.
If either the external TA pin or internal chip-select transfer acknowledge
signal is asserted before the end of state 1, the EBI proceeds to state 2.
19.7.1.2 Optional Wait States (X2W)
Wait states are inserted until the slave asserts the TA pin or the internal
chip-select transfer acknowledge signal is asserted. Wait states are
counted in full clocks.
19.7.1.3 State 2 (X2)
One-half clock later in state 2, the selected device puts its information on
D[31:16] and/or D[15:0]. One or both half-words of the external data bus
are driven to the internal data bus.
The address bus, R/W, CS, OE, EB, TC, and TSIZ pins remain valid
through state 2 to allow for static memory operation and signal skew.
The slave device asserts data until it detects the negation of OE, after
which it and must remove its data within approximately one-half of a
state. Note that the data bus may not become free until state 1.
Technical Data
512
External Bus Interface Module (EBI)
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MMC2107 – Rev. 2.0
MOTOROLA