External Memory Controller
LH79524/LH79525 User’s Guide
7-50
Version 1.0
NOTES:
1. A Chip Select can be connected to a single memory device, in this case the Chip Select data bus width is
the same as the device width. Alternatively the Chip Select can be connected to a number of external
devices. In this case the Chip Select data bus width is the sum of the memory device data bus widths. For
example, for a Chip Select connected to:
– a 32-bit wide memory device, choose a 32-bit wide address mapping.
– a 16-bit wide memory device, choose a 16-bit wide address mapping.
– four x 8-bit wide memory devices, choose a 32-bit wide address mapping.
– two x 8-bit wide memory devices, choose a 16-bit wide address mapping.
2. The SDRAM column and row width and number of banks are computed automatically from the
address mapping.
3. The SDRAM section of the memory controller does a constant burst of 8 when configured to access 16 bit
memory devices. Similarly, it does burst of 4 when configured to access 32-bit memory devices.
32-BIT EXTERNAL BUS LOW POWER SDRAM ADDRESS MAPPING (ROW, BANK, COLUMN)
1
1
000
00
16Mb (2M
×
8), 2 banks, row length = 11, column length = 9
1
1
000
01
16Mb (1M
×
16), 2 banks, row length = 11, column length = 8
1
1
001
00
64Mb (8M
×
8), 4 banks, row length = 12, column length = 9
1
1
001
01
64Mb (4M
×
16), 4 banks, row length = 12, column length = 8
1
1
001
10
64Mb (4M
×
16), 4 banks, row length = 11, column length = 8
1
1
010
00
128Mb (16M
×
8), 4 banks, row length = 12, column length = 10
1
1
010
01
128Mb (8M
×
16), 4 banks, row length = 12, column length = 9
1
1
010
10
128Mb (8M
×
16), 4 banks, row length = 12, column length = 8
1
1
011
00
256Mb (32M
×
8), 4 banks, row length = 13, column length = 10
1
1
011
01
256Mb (16M
×
16), 4 banks, row length = 13, column length = 9
1
1
011
10
256Mb (16M
×
16), 4 banks, row length = 13, column length = 8
1
1
100
00
512Mb (64M
×
8), 4 banks, row length = 13, column length = 11
1
1
100
01
512Mb (32M
×
16), 4 banks, row length = 13, column length = 10
Table 7-49. Address Mapping (Cont’d)
DYNCFGx BITS
DESCRIPTION
[14]
[12]
[11:9]
[8:7]