MCF548x Reference Manual, Rev. 3
19-18 Freescale Semiconductor

19.3.2.6 Initiator Window 1 Base/Translation Address Register (PCIIW1BTAR)

The field descriptions for this register are the same as for PCIIW0BTAR, except that they apply to Window

1.

Table 19-14. PCIIW0BTAR Field Descriptions

Bits Name Description
31–24 Window 0
Base
Address
One of three base address registers to determine an XL bus hit on PCI. At most, the upper byte of
the address is decoded. The Window 0 Address Mask register determines what bits of this register
to compare the XL bus address against to generate the hit.
The smallest possible Window is a 16-Mbyte block.
23–16 Window 0
Address
Mask
The Window 0 Address Mask Register masks the corresponding XL bus base address bit of the
base address for Window 0 (Window 0 Base Address) to instruct the address decode logic to
ignore or “don’t care” the bit. If the base address mask bit is set, the associated base address bit
of Window 0 is ignored when generating the PCI hit. Bit 16 masks bit 24, bit 17 masks bit 25, and
so on.
0 Corresponding address bit is used in address decode.
1 Corresponding address bit is ignored in address decode.
For XL bus accesses to Window 0 address range, this byte also determines which upper 8 bits of
the XL bus address to pass on for presentation as a PCI address. Any address bit used to decode
the XL bus address, indicated by a “0”, will be translated. This provides a way to overlay a PCI page
address onto the XL bus address. A “1” in the Address Mask byte indicates that the XL bus address
bit will be passed to PCI unaltered.
15–8 Window 0
Translation
Address
For any translated bit (described above), the corresponding value here will be driven onto the PCI
address bus for the XL bus Window 0 address hit.
The Window Translation operation can not be turned off. If a direct mapping from XL bus to PCI
space is desired, program the same value to both the Window Base Address Register and Window
Translation Address Register.
7–0 Reserved, should be cleared.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R Window 1 Base Address Window 1 Address Mask
W
Reset0000000000000000
1514131211109876543210
R Window 1 Translation Address 00000000
W
Reset0000000000000000
Reg
Addr
MBAR + 0xB74

Figure 19-14. Initiator Window 1 Base/Translation Address Register (PCIIW1BTAR)