Chapter 6: SDRAM Memory Controller
TX7901 User’s Manual (Rev. 6.30T – Nov, 2001)
6-3
Figure 6-2 Initial Setting after Reset
Programming note
It is okay to place multiple DIMMs into a region. It is okay to place two DIMMs into
consecutive physical addresses. However, it is not okay to place a DIMM across two
regions. In other words, placing a DIMM across region boundaries is not permitted. This
violation can be detected by reading the HIGH register again after LOW and HIGH are
written. If the HIGH register is read the same as it was written, then it is okay. If it is different
because the HIGH region field is the same as that of LOW, then it is okay to place a DIMM
across the 256 MB region boundary.
la r4, <LOW of DIMM0>
la r5, <HIGH of DIMM1>
la r7, <SDRAM base address>
sq r4, D0LOW (r7)
sq r5, D0HIGH (r7)
lq r6, D0HIGH (r7)
bne r5, r6, crossing DIMM
0xFFFF_FFFF
0x1000_0000
0x0000_0000
Region0
DIMM3 (8 MB)
DIMM2 (8 MB)
DIMM1 (8 MB)
DIMM0 (8 MB)
0x0FFF_FFFF
0x0000_0000
0x0080_0000
0x0100_0000
0x0180_0000
0x0200_0000
D0 HIGH
D0 LOW
D1 HIGH
D1 LOW
D2 HIGH
D2 LOW
D3 HIGH
D3 LOW
Содержание TMPR7901
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Страница 14: ...Handling Precautions ...
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Страница 41: ...4 Precautions and Usage Considerations 4 2 ...
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