Intel IXP42X 用户手册
Intel
®
IXP42X product line and IXC1100 control plane processors—Expansion Bus Controller
Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
DM
September 2006
296
Order Number: 252480-006US
Table 118.
Expansion Bus Address and Data Byte Steering
South AHB
Bus Cycle
Device
Connected to
Expansion Bus
(8-bit or 16-
bit)
South AHB
Address Value
(SAHB_ADDR[1:0]
)
Expansion Bus
Address Value
(EX_ADDR[1:0]
)
Data Location Translation Between
Expansion Data Bus and South AHB Data Bus
32-bit write
8-bit
32-bit write
16-bit
32-bit read
8-bit
00
00
AHB data bus [31:24] ← Expansion data bus
[7:0]
01
AHB data bus [23:16] ← Expansion data bus
[7:0]
10
AHB data bus [15:8] ← Expansion data bus [7:0]
11
AHB data bus [7:0] ← Expansion data bus [7:0]
32-bit read
16-bit
00
0x
AHB data bus [31:16] ← Expansion data bus
[15:0]
1x
AHB data bus [15:0] ← Expansion data bus
[15:0]
16-bit read
8-bit
16-bit read
16-bit
0x
0x
AHB data bus [31:16] ← Expansion data bus
[15:0]
16-bit
1x
1x
AHB data bus [15:0] ← Expansion data bus
[15:0]
16-bit write
8-bit
16-bit write
16-bit
0x
0x
AHB data bus [31:16] → Expansion data bus
[15:0]
16-bit
1x
1x
AHB data bus [15:0] → Expansion data bus
[15:0]
8-bit read
8-bit
00
00
AHB data bus [31:24] ← Expansion data bus
[7:0]
8-bit
01
01
AHB data bus [23:16] ← Expansion data bus
[7:0]
8-bit
10
10
AHB data bus [15:8] ← Expansion data bus [7:0]
8-bit
11
11
AHB data bus [7:0] ← Expansion data bus [7:0]
8-bit read
16-bit
BYTE_RD16 dependant
8-bit write
8-bit
00
00
AHB data bus [31:24] → Expansion data bus
[7:0]
8-bit
01
01
AHB data bus [23:16] → Expansion data bus
[7:0]
8-bit
10
10
AHB data bus [15:8] → Expansion data bus [7:0]
8-bit
11
11
AHB data bus [7:0] → Expansion data bus [7:0]
8-bit write
16-bit
Not allowed.
This will cause an AHB error that will result in a data-abort error.