CHAPTER 3 SPECIFICATIONS OF PCI HOST BRIDGE MACRO
Application Note U17121EJ1V1AN
42
3.4.10 SDRAM_CTL register
After reset: 00070230H R/W Offset address: 48H
31 24
23 16 15
13 12 11 10
9 8 7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 0
CYCLE_LATENCY
0 0 0
BUS_SIZE
0 0
CAS_LATENCY
0 0
W
A
IT_STATE
0 0
COLUM
N
_SIZE
Bit Name
R/W
Function
CYCLE_LATENCY R/W Sets the latency for successive main memory (SDRAM) accesses from the PCI device.
A latency of up to 7,650 ns can be set.
00H: No latency
01H: 1 PCI clock (30 ns)
:
FFH: 255 PCI clocks (7,650 ns)
BUS_SIZE R/W
Sets the bit width of the data bus.
0: 16-bit width
1: 32-bit width
CAS_LATENCY R/W
Sets the CAS latency.
00: Setting prohibited
01:
1
10:
2
11:
3
WAIT_STATE R/W
Sets the wait interval of ACT
→
CMD, PRE
→
ACT, and CMD
→
ACT.
00: Setting prohibited
01: 1 clock
10: 2 clocks
11: 3 clocks
COLUMN_SIZE R/W
Sets the bit width of the column address.
00: 8-bit width
01: 9-bit width
10: 10-bit width
11: 11-bit width