Appendix B. Bit and Byte Ordering
B-3
Big-Endian Mode
Figure B-1 shows a 4-byte write to PCI memory space in big-endian mode.
Figure B-1. Four-Byte Transfer to PCI Memory Space—Big-Endian Mode
Note that the MSB on the internal peripheral logic bus, D0, is placed on byte lane 0
(AD[7–0]) on the PCI bus. This occurs so D0 appears at address 0xnnnn_nn00 and not at
address 0xnnnn_nn03 in the PCI space.
Processor
0 0 0 0
0
1
2
3
4
5
6
7
D0
D1
D2
D3
xx
xx
xx
xx
3
2
1
0
D3
D2
D1
D0
D3
D2
D1
D0
0x00
0x08
PCI Big-Endian Memory Space
Byte lanes
PCI byte lanes (C/BE[3–0] asserted)
0 0 0 0
AD[3–0]
During address phase
(AD[1–0] = 0b00 for memory space access)
Runs PCI memory transaction
PCI data bus
(AD[7–0], AD[15–8], AD[23–16], and AD[31–24]
during data phase)
Core
PA[28–31]
Internal peripheral logic data bus
CDU
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...