MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
11-1
Chapter 11
L-Bus to U-Bus Interface (L2U)
The L-bus to U-bus interface unit (L2U) provides an interface between the load/store bus (L-bus) and the
unified bus (U-bus). The L2U module includes the data memory protection unit (DMPU), which provides
protection for data memory accesses.
The L2U is bidirectional. It allows load/store accesses not intended for the L-bus data RAM to go to the
U-bus. It also allows code execution from the L-bus data RAM and read/write accesses from the U-bus to
the L-bus.
The L2U directs bus traffic between the L-bus and the U-bus. When transactions start concurrently on both
buses, the L2U interface arbitrates to select which transaction is handled. The top priority is assigned to
U-bus to L-bus accesses; lower priority is assigned to the load/store accesses by the RCPU.
11.1
General Features
•
Non-pipelined master and slave on U-bus
— Does not start two back-to-back accesses on the U-bus
— Supports U-bus pipelining
— Retries back-to-back accesses from U-bus masters
•
Non-pipelined master and slave on the L-bus
•
Generates module selects for L-bus memory-mapped resources within a programmable,
contiguous block of storage
•
Programmable data memory protection unit (DMPU)
•
L-bus and U-bus snoop logic for the reservation protocol compatible with the PowerPC ISA
architecture
•
Show cycles for RCPU accesses to the CALRAM (none, all, writes)
— Protection for CALRAM accesses from the U-bus side (all accesses to the CALRAM from the
U-bus side are blocked once the CALRAM protection bit is set)
11.2
Data Memory Protection Unit Features
•
Supports four memory regions whose base address and size can be programmed
— Available sizes are 4 Kbytes, 8 Kbytes, 16 Kbytes, 32 Kbytes, 64 Kbytes, 128 Kbytes, 256
Kbytes, 512 Kbytes, 1 Mbyte, 2 Mbytes, 4 Mbytes, 8 Mbytes, and 16 Mybtes
— Region must start on the specified region size boundary (modulo addressing)
— Overlap between regions is allowed
•
Each of the four regions supports the following attributes:
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...