UM10413
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User manual
Rev. 1 — 16 December 2011
16 of 268
NXP Semiconductors
UM10413
MPT612 User manual
Mode 1:
MAM partially enabled. If the data is present, sequential instruction accesses
are fulfilled by the holding latches. Instruction prefetch is enabled. Non-sequential
instruction accesses initiate flash read operations (see
, note 2). This means that
all branches cause memory fetches. All data operations cause a flash read because
buffered data access timing is hard to predict and is very situation-dependent.
Mode 2:
MAM fully enabled. Any memory request (code or data) for a value that is
contained in one of the corresponding holding latches is fulfilled from the latch.
Instruction prefetch is enabled. Flash read operations are initiated for instruction
prefetch and code or data values not available in the corresponding holding latches.
[1]
Instruction prefetch is enabled in modes 1 and 2.
[2]
If available, the MAM actually uses latched data, but mimics the timing of a flash read operation. This
method saves power while resulting in the same execution timing. The MAM can truly be turned off by
setting the fetch timing value in MAMTIM to one clock.
[1]
If available, the MAM actually uses latched data, but it mimics the timing of a flash read operation. This
method saves power while resulting in the same execution timing. The MAM can truly be turned off by
setting the fetch timing value in MAMTIM to one clock.
8.4 MAM
configuration
After reset the MAM defaults to the disabled state. Software can turn memory access
acceleration on or off at any time. This method allows most of an application to be run at
the highest possible performance, while certain functions can be run at a slower but more
predictable rate if more precise timing is required.
8.5 Register
description
All registers, regardless of size, are on word address boundaries. Details of the registers
appear in the description of each function.
Table 5.
MAM Responses to program accesses of various types
Program memory request type
MAM mode
0
1
2
Sequential access, data in latches
initiate fetch
use latched
data
use latched
data
Sequential access, data not in latches
initiate fetch
initiate fetch
initiate fetch
Non-sequential access, data in latches
initiate fetch
initiate fetch
use latched
data
Non-sequential access, data not in latches initiate fetch
initiate fetch
initiate fetch
Table 6.
MAM responses to data accesses of various types
Data memory request type
MAM mode
0
1
2
Sequential access, data in latches
initiate fetch
initiate fetch
use latched data
Sequential access, data not in latches
initiate fetch
initiate fetch
initiate fetch
Non-sequential access, data in latches
initiate fetch
initiate fetch
use latched data
Non-sequential access, data not in latches initiate fetch
initiate fetch
initiate fetch