MMC2107 Datasheet, PDF (517/618 Pages) –

Freescale Semiconductor, Inc.
External Bus Interface Module (EBI)
Emulation Support
D28 pin is driven low during reset configuration to disable the internal
FLASH so that no conflict exists with the external memory device. It
should be noted that at higher frequencies writes to external memories
emulating the internal memories may require one clock for read
accesses and two clocks for write accesses.
Table 19-4. Emulation Mode Chip-Select Summary⁽¹⁾
CSE1
CSE0
Indication in Emulation Mode
Internal access to any register space (excluding ports)
1
1
Reset state
(0x00c1_0000:0x00ff_ffff)
1
0
Internal access to ports register space
(0x00c0_0000:0x00c0_ffff)
0
1
Internal access not covered by CSE encoding = 11, 10
(0x0000_0000:0x00bf_ffff; 0x0100_0000:0x07ff_ffff)
0
0
External access
(0x8000_0000 to 0xffff_ffff)
1. CSE[1:0] is valid only for the duration of valid bus cycles or reset. Undefined otherwise.
19.9.2 Internal Data Transfer Display (Show Cycles)
Internal data transfers normally occur without showing the internal data
bus activity on the external data bus. For debugging purposes, however,
it may be desirable to have internal cycle data appear on the external
bus. These external bus cycles are referred to as show cycles and are
distinguished from normal external cycles by the fact that OE and
EB[3:0] remain negated.
Regardless of whether show cycles are enabled, the EBI drives the
address bus, TC[2:0], TSIZ[1:0] and R/W signals, indicating the internal
cycle activity. When show cycles are disabled, D[31:0] remains in a high
impedance state. When show cycles are enabled, OE and EB[3:0]
remain negated while the internal data is presented on D[31:0] on the
first clock tick after the termination of the internal cycle.
Show cycles are always enabled in emulation mode. In master mode,
show cycles are disabled coming out of reset and must be enabled by
writing to the SHEN bit in the chip configuration register (CCR).
MMC2107 – Rev. 2.0
MOTOROLA
External Bus Interface Module (EBI)
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Technical Data
517