TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual
13-84
V2.0, 2007-07
EBU, V2.0
TIMEOUTC
[15:8]
rw
Bus Time-out Control
This bit field determines the number of inactive cycles
leading to a bus time-out after the EBU gains
ownership.
00
H
Time-out is disabled.
01
H
Time-out is generated after 1
×
8 clock cycles.
…
H
…
FF
H
Time-out is generated after 255
×
8 clock
cycles.
GLOBALCS
[19:16] rw
Global Chip Select Signal
The bits of this bit field are used to enable the EBU
chip select lines for the global chip select CSGLB
generation. With x = 0-3, the GLOBALCS bits are
defined as follows (see also
0
B
CSGLB is not activated by an active CSx.
1
B
CSGLB is activated when CSx becomes active.
CS0FAM
27
rw
CS0 Fills Address Map
0
B
Normal region/chip select logic is in operation.
1
B
Normal region/chip select logic is disabled. The
Chip Select 0 Address Override Mode is
selected. All external bus accesses are directed
to Region 0 (CS0).
This bit is set following reset in external boot mode
(see
) which ensures that the CPU to
which the EBU is connected can boot from external
memory, regardless of the CPU specific boot
address.
EMUFAM
28
rw
CSEMU Fills Address Map
0
B
Normal region/chip select logic is in operation.
1
B
Normal region/chip select logic is disabled. The
Emulator Chip Select Address Override Mode
is selected. All external bus accesses are
directed to the Emulator Region (CSEMU).
This bit has no effect when bit CS0FAM is 1. It is set
following reset in emulation mode (see
),
which ensures that the CPU to which the EBU is
connected can boot from emulation memory
regardless of the CPU-specific boot address.
Field
Bits
Type Description