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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 Not allowed.
32-bit write 16-bit Not allowed.
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 Not allowed.
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 Not allowed.
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.