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DS785UM1
Copyright 2007 Cirrus Logic
ARM920T Core and Advanced High-Speed Bus (AHB)
EP93xx User’s Guide
2
2
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2.2.3.3.2 Data Cache Enable
•
A write to bit 2 of CP15 register 1 will enable or disable the Data Cache (D-Cache)/Write
Buffer
•
The D-Cache may only be enabled when the MMU is enabled. All data accesses are
subject to MMU and permission checks
•
If disabled, current contents are ignored. If re-enabled before a reset, contents will be
unchanged, but may not be coherent with external memory. Depending on system
software, a clean and invalidate action may be required before re-enabling.
2.2.3.3.3 Write Buffer Enable
•
The Write Buffer is enabled via the page table entries in the MMU. The Write buffer
cannot be enabled unless the MMU is enabled.
2.2.4 Co-processor Interface
The MaverickCrunch co-processor is explained in detail in
. The
relationship between the ARM co-processor instructions and MaverickCrunch co-processor
is also explained in
The ARM co-processor instruction set includes:
•
LDC - Load co-processor from memory
•
STC - Store co-processor register from memory
•
MRC - Move to ARM register from co-processor register
•
MCR - Move to co-processor register from ARM register
The ARM co-processor has sixteen (C0 through C15) 64-bit registers for data transfer and
data manipulation. See
for a code example.
2.2.5 AMBA AHB Bus Interface Overview
The AHB (Advanced High-Performance Bus) is the high-performance system backbone bus.
shows a typical AMBA AHB System.
The AHB connects devices that require high bandwidth, such as DMA controllers, external
memory, and co-processors. The AHB supports:
•
Burst Transactions
•
Split Transactions
•
Bus Master hand-over to devices such as the MaverickCrunch co-processor or DMA
controller
•
Single clock edge operations
The APB (Advanced Peripheral Bus) is a lower bandwidth, but lower power, bus that
provides:
Summary of Contents for EP93 Series
Page 28: ...P 6 DS785UM1 Copyright 2007 Cirrus Logic Preface EP93xx User s Guide PP P ...
Page 162: ...5 36 DS785UM1 Copyright 2007 Cirrus Logic System Controller EP93xx User s Guide 55 5 ...
Page 576: ...15 18 DS785UM1 Copyright 2007 Cirrus Logic UART2 EP93xx User s Guide 1515 15 ...
Page 634: ...17 38 DS785UM1 Copyright 2007 Cirrus Logic IrDA EP93xx User s Guide 1717 17 ...
Page 648: ...19 6 DS785UM1 Copyright 2007 Cirrus Logic Watchdog Timer EP93xx User s Guide 1919 19 ...
Page 688: ...21 32 DS785UM1 Copyright 2007 Cirrus Logic I2S Controller EP93xx User s Guide 2121 21 ...
Page 790: ...27 20 DS785UM1 Copyright 2007 Cirrus Logic IDE Interface EP93xx User s Guide 2727 27 ...
Page 808: ...28 18 DS785UM1 Copyright 2007 Cirrus Logic GPIO Interface EP93xx User s Guide 2828 28 ...