AM1802 Datasheet, PDF (7/180 Pages) Texas Instruments – AM1802 ARM Microprocessor

AM1802
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SPRS710C – NOVEMBER 2010 – REVISED MARCH 2012
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• Invalidate entire TLB, using CP15 register 8
• Invalidate TLB entry, selected by MVA, using CP15 register 8
• Lockdown of TLB entries, using CP15 register 10
2.3.4 Caches and Write Buffer
The size of the Instruction cache is 16KB, Data cache is 16KB. Additionally, the caches have the following
features:
• Virtual index, virtual tag, and addressed using the Modified Virtual Address (MVA)
• Four-way set associative, with a cache line length of eight words per line (32-bytes per line) and with
two dirty bits in the Dcache
• Dcache supports write-through and write-back (or copy back) cache operation, selected by memory
region using the C and B bits in the MMU translation tables
• Critical-word first cache refilling
• Cache lockdown registers enable control over which cache ways are used for allocation on a line fill,
providing a mechanism for both lockdown, and controlling cache corruption
• Dcache stores the Physical Address TAG (PA TAG) corresponding to each Dcache entry in the TAG
RAM for use during the cache line write-backs, in addition to the Virtual Address TAG stored in the
TAG RAM. This means that the MMU is not involved in Dcache write-back operations, removing the
possibility of TLB misses related to the write-back address.
• Cache maintenance operations provide efficient invalidation of, the entire Dcache or Icache, regions of
the Dcache or Icache, and regions of virtual memory.
The write buffer is used for all writes to a noncachable bufferable region, write-through region and write
misses to a write-back region. A separate buffer is incorporated in the Dcache for holding write-back for
cache line evictions or cleaning of dirty cache lines. The main write buffer has 16-word data buffer and a
four-address buffer. The Dcache write-back has eight data word entries and a single address entry.
2.3.5 Advanced High-Performance Bus (AHB)
The ARM Subsystem uses the AHB port of the ARM926EJ-S to connect the ARM to the Config bus and
the external memories. Arbiters are employed to arbitrate access to the separate D-AHB and I-AHB by the
Config Bus and the external memories bus.
2.3.6 Embedded Trace Macrocell (ETM) and Embedded Trace Buffer (ETB)
To support real-time trace, the ARM926EJ-S processor provides an interface to enable connection of an
Embedded Trace Macrocell (ETM). The ARM926ES-J Subsystem in the device also includes the
Embedded Trace Buffer (ETB). The ETM consists of two parts:
• Trace Port provides real-time trace capability for the ARM9.
• Triggering facilities provide trigger resources, which include address and data comparators, counter,
and sequencers.
The device trace port is not pinned out and is instead only connected to the Embedded Trace Buffer. The
ETB has a 4KB buffer memory. ETB enabled debug tools are required to read/interpret the captured trace
data.
2.3.7 ARM Memory Mapping
By default the ARM has access to most on and off chip memory areas, including EMIFA, DDR2, and the
additional 128K byte on chip SRAM. Likewise almost all of the on chip peripherals are accessible to the
ARM by default.
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