XC2200 Derivatives
System Units (Vol. 1 of 2)
The External Bus Controller EBC
User’s Manual
9-24
V2.1, 2008-08
EBC_X8, V1.0d1
controlled separately, whereby the different address areas (windows) are defined by the
ADDRSELx registers. 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 (
). 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.
The address area from 00’8000
H
to 00’FFFF
H
(32 Kbytes) is reserved for CPU internal
registers and data RAM, the area from BF’0000
H
to BF’7FFF
H
(32 Kbytes) for internal
startup memory and the area from C0’0000
H
to FF’FFFF
H
(4 Mbytes) is used by the
internal program memory. Therefore, these address areas cannot be used by external
resources connected to the external bus.
Note: The range start address can only be on boundaries specified by the selected
Table 9-4
Address Range and Size for ADDRSELx
ADDRSELx
Address Window
Range
Size
RGSZ
Relevant (R) Bits
of RGSAD
Selected
Address
Range
Range Start Address A[23:0]
Selected with R-bits of RGSAD
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 Mbytes 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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