Address Mapping - Toshiba TMPR4925 Manual

7.3.3

Address Mapping

Each of the eight channels can use the Base Address field (EBBAR.BA[31:20]) and the Channel Size
field (EBCCRn.CS[3:0]) of the External Bus Channel Control Register to map to any physical address.
A channel is selected when the following equation becomes True.
paddr[31:20] & !Mask[31:20] == BA[31:20] & !Mask[31:20]
In the above equation, paddr represents the accessed physical address, Mask[31:20] represents the
address mask value selected from Table 7.3.1 from the Channel Size, the ampersand (&) represents the
AND operation, and the exclamation mark (!) represents the Logical NOT for each bit.
Operation is indeterminate when either multiple channels are selected simultaneously, or a channel is
selected simultaneously with the SDRAM Controller or PCI Controller.
CS[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Chapter 7 External Bus Controller
Table 7.3.2 Address Mask
Channel Size Address Mask[31:20]
1 MB 0000_0000_0000
2 MB 0000_0000_0001
4 MB 0000_0000_0011
8 MB 0000_0000_0111
16 MB 0000_0000_1111
32 MB 0000_0001_1111
64 MB 0000_0011_1111
128 MB 0000_0111_1111
256 MB 0000_1111_1111
512 MB 0001_1111_1111
1 GB 0011_1111_1111
Reserved
Reserved
Reserved
Reserved
Reserved
7-5
Reserved
Reserved
Reserved
Reserved
Reserved