
User Manual
C166S V2
External Bus Controller
User Manual
6-165
V 1.7, 2001-01
of the four different bus modes independently. Each ADDRSELx register cuts out an
address window, where the corresponding parameters of the registers FCONCSx and
TCONCSx are used to control external accesses. The range start address of such a
window defines the most significant address bits of the selected window which are
consequently not needed to address the memory/module in this window (
Table 6-2
).
The size of the window chosen by ADDRSELx.RGSZ defines the relevant bits of
ADDRSELx.RGSAD (marked with
‘
R
’
) which are used to select with the most significant
bits of the request address the corresponding window. The other bits of the request
address are used to address the memory locations inside this window. The lower bits of
ADDRSELx.RGSAD (marked
‘
x
’
) are disregarded.
Two additional chip select channels, which are used for accessing the startup and the
monitor memory, are located in a predefined address range. The size of these two
address areas is fixed to 32 kByte.
The address area from 00
’
8000
H
to 00
’
FFFF
H
(32 kbyte) is reserved for C166S V2 CPU
internal I/O, the area from BF
’
0000
H
to BF
’
FFFF
H
(64 kbyte) for startup and monitor
memory and the area from C0
’
0000
H
to FF
’
FFFF
H
(4 Mbyte) is used by the internal
program memory. Therefore, these address areas cannot be used by external resources
connected to the external bus.
Table 6-2
Address range and size for ADDRSELx
Note: The range start address can only be on boundaries specified by the selected
range size according to
Table 6-2
.
ADDRSELx
Relevant (R) bits
of RGSAD
Address Window
Range start address A[23:0]
selected with R-bits of RGSAD
Range
Size
RGSZ
Selected
address range
3..0
15
...
4
size
A23
...
A0
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
11xx
RRRR RRRR RRRR
RRRR RRRR RRRx
RRRR RRRR RRxx
RRRR RRRR Rxxx
RRRR RRRR xxxx
RRRR RRRx xxxx
RRRR RRxx xxxx
RRRR Rxxx xxxx
RRRR xxxx xxxx
RRRx xxxx xxxx
RRxx xxxx xxxx
Rxxx xxxx xxxx
xxxx xxxx xxxx
4 KBytes
8 KBytes
16 KBytes
32 KBytes
64 KBytes
128 KBytes
256 KBytes
512 KBytes
1 MBytes
2 MBytes
4 MBytes
8 MBytes
reserved
1)
1)
The complete address space of 12 MByte can be selected by the default chip select CS0.
RRRR RRRR RRRR 0000 0000 0000
RRRR RRRR RRR0 0000 0000 0000
RRRR RRRR RR00 0000 0000 0000
RRRR RRRR R000 0000 0000 0000
RRRR RRRR 0000 0000 0000 0000
RRRR RRR0 0000 0000 0000 0000
RRRR RR00 0000 0000 0000 0000
RRRR R000 0000 0000 0000 0000
RRRR 0000 0000 0000 0000 0000
RRR0 0000 0000 0000 0000 0000
RR00 0000 0000 0000 0000 0000
R000 0000 0000 0000 0000 0000
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