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Device Performance Optimization
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
33-6
33.3.5
Cache
33.3.5.1
Description
The PXR40 provides an 16kB Instruction and 16kB Data, 4-way set-associative, harvard cache design
with a 32-byte line size. The cache is disabled by default when reset is negated.
The cache improves system performance by providing low-latency instructions and data to the e200z7
instruction and data pipelines, which decouples processor performance from system memory performance.
There are several stages to enabling the cache. Not only does the cache itself have to be invalidated then
enabled, but memory regions upon which it can operate must be configured in the MMU to permit cache
access.
33.3.5.2
Recommended configuration
The exact usage of cache is application dependent but some general guidelines for using cache to improve
performance in a typical application are listed below:
•
Enable instruction cache for all internal & external memories that code is being executed from.
•
Enable data cache for internal data memories that are not shared, unless the application can
guarantee that coherency is maintained between multiple masters.
•
Consider locking the stack within the data cache.
•
Copyback mode in the cache generally uses fewer system resources. However, write through mode
is better for coherency and to protect for future multi-core devices that require write-thorough
mode be set for inter-core coherency.
•
Consider locking critical performance routines in cache.
•
Avoid caching memory mapped peripherals for coherency reasons.
The process of enabling the instruction cache involves first invalidating the cache (by setting
L1CSR1[ICINV]) then when invalidation is completed (L1CSR1[ICINV, ICABT]=0) enabling the cache
(by setting L1CSR1[ICE]). A similar process for the data cache using L1CSR0 is required.
The L1CSR1 and L1CSR0 special purpose registers are detailed below. For further details of cache
configuration registers refer to the e200z7 core reference manual.
0
ICEC
E
ICEI
0
ICEDT
0
ICUL
IC
LO
ICLFC
ICLO
A
IC
EA
0
ICABT
IC
INV
IC
E
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
SPR - 1011; Read/Write; Reset - 0x0
Figure 33-2. L1 Cache Control & status Register 1 (L1CSR1)
Table 33-2. L1CSR1 Register Field Descriptions
Field
Description
0–14
Reserved
15
ICECE
Instruction Cache Error Checking Enable
Содержание PXR4030
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Страница 66: ...Memory Map PXR40 Microcontroller Reference Manual Rev 1 2 4 Freescale Semiconductor...
Страница 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 158: ...Power Management Controller PMC 5 26 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 182: ...Frequency Modulated Phase Locked Loop FMPLL 6 24 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 278: ...System Integration Unit SIU 7 96 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 280: ...System Information Module PXR40 Microcontroller Reference Manual Rev 1 8 2 Freescale Semiconductor...
Страница 300: ...Boot Assist Module BAM 9 20 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 346: ...Interrupts and Interrupt Controller INTC 10 46 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 352: ...General Purpose Static RAM SRAM 11 6 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 432: ...Core e200z7 Overview PXR40 Microcontroller Reference Manual Rev 1 13 44 Freescale Semiconductor...
Страница 460: ...Peripheral Bridge PBRIDGE 15 16 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 478: ...Memory Protection Unit MPU 16 18 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 496: ...Error Correction Status Module ECSM 17 18 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 524: ...Periodic Interrupt Timer PIT_RTI 20 12 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 740: ...FlexRay Communication Controller FLEXRAY 22 156 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 928: ...Deserial Serial Peripheral Interface DSPI 25 68 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 982: ...Enhanced Serial Communication Interface eSCI 26 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1114: ...Enhanced Queued Analog to Digital Converter EQADC 27 132 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1167: ...Decimation Filter Freescale Semiconductor 28 53 PXR40 Microcontroller Reference Manual Rev 1...
Страница 1168: ...Decimation Filter 28 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1262: ...Enhanced Time Processing Unit eTPU2 29 94 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1399: ...Nexus Development Interface NDI Freescale Semiconductor 31 83 PXR40 Microcontroller Reference Manual Rev 1...
Страница 1400: ...Nexus Development Interface NDI 31 84 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...