MMC2107 - Freescale Semiconductor

External Bus Interface Module (EBI)
Freescale Semiconductor, Inc.
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Freescale Semiconductor, I
19.2 Introduction
19.8 Bus Exception Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .516
19.8.1 Transfer Error Termination . . . . . . . . . . . . . . . . . . . . . . . . .516
19.8.2 Transfer Abort Termination . . . . . . . . . . . . . . . . . . . . . . . .516
19.9 Emulation Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .516
19.9.1 Emulation Chip-Selects (CSE[1:0]) . . . . . . . . . . . . . . . . . .516
19.9.2 Internal Data Transfer Display (Show Cycles) . . . . . . . . . .517
19.9.3 Show Strobe (SHS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .518
19.10 Bus Monitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .519
19.11 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .520
The external bus interface (EBI) module is responsible for controlling the
transfer of information between the internal M•CORE local bus and
external address space. The external bus has 23 address lines and 32
data lines.
In master mode and emulation mode, the EBI functions as a bus master
and allows internal bus cycles to access external resources. In
single-chip mode, the EBI is active, but the external data bus is not
available, and no external data or termination signals are transferred to
the internal bus.
The EBI supports data transfers to both 32-bit and 16-bit ports.
Chip-select channels are programmed to define the port size for specific
address ranges. When no chip-select is active during an external data
transfer, the port size is assumed to be 32 bits.
The EBI supports a variable length external bus cycle to accommodate
the access speed of any device. During an external data transfer, the
EBI drives the address pins, byte enable pins, output enable pins, size
pins, and read/write pins. Wait states are inserted until the bus cycle is
terminated by the assertion of the internal transfer acknowledge signal
by a chip-select channel or by the assertion of the external TA or TEA
pins. The minimum external bus cycle is one clock.
Technical Data MMC2107 – Rev. 2.0
504 External Bus Interface Module (EBI) MOTOROLA
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