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External Bus Interface (EBI)
Freescale Semiconductor
30-31
PXR40 Microcontroller Reference Manual, Rev. 1
The general case of burst transfers assumes that the external memory has 32-bit port size and 8-word burst
length. The EBI can also burst from 16-bit port size memories, taking twice as many external beats to fetch
the data as compared to a 32-bit port with the same burst length. The EBI can also burst from 16-bit or
32-bit memories that have a 4-word burst length (BL=1 in the appropriate Base Register). In this case, two
external 4-word burst transfers (wrapping on 4-word boundary) are performed to fulfill the internal 8-word
request
1
. This operation is considered atomic by the EBI, so the EBI does not allow other unrelated master
accesses or bus arbitration to intervene between the transfers. For more details and a timing diagram, see
Section 30.4.2.6.3, Small Access Example #3: 32-byte Read to 32-bit Port with BL=1
.
During burst cycles, the D_BDIP (Burst Data In Progress) signal is used to indicate the duration of the
burst data. During the data phase of a burst read cycle, the EBI receives data from the addressed slave. If
the EBI needs more than one data, it asserts the D_BDIP signal. Upon receiving the data prior to the last
data, the EBI negates D_BDIP. Thus, the slave stops driving new data after it receives the negation of
D_BDIP on the rising edge of the clock. Some slave devices have their burst length and timing
configurable internally and thus may not support connecting to a D_BDIP pin. In this case, D_BDIP is
driven by the EBI normally, but the output is ignored by the memory and the burst data behavior is
determined by the internal configuration of the EBI and slave device. When the TBDIP bit is set in the
appropriate Base Register, the timing for D_BDIP is altered. See
Section 30.4.2.5.1, TBDIP Effect on
for this timing.
Since burst writes are not supported by the EBI
2
, the EBI negates D_BDIP during write cycles.
Table 30-13. Wrap Bursts Order
Burst Starting Address
D_ADD[27:28]
Burst Order
(Assuming 32-bit Port Size)
00
word0 -> word1 -> word2 -> word3 -> word4 -> word5 -> word6 -> word7
01
word2 -> word3 -> word4 -> word5 -> word6 -> word7 -> word0 -> word1
10
word4 -> word5 -> word6 -> word7 -> word0 -> word1 -> word2 -> word3
11
word6 -> word7 -> word0 -> word1 -> word2 -> word3 -> word4 -> word5
1.
This case (of 2 external burst transfers being required) applies only to AMBA data bus width of 64 bits.
2.
Except for the special case of a 32-bit non-chip-select access in 16-bit data bus mode. See
Non-Chip-Select Burst in 16-bit Data Bus Mode
.
Содержание PXR4030
Страница 1: ...PXR40 Microcontroller Reference Manual Devices Supported PXR4030 PXR4040 PXR40RM Rev 1 06 2011...
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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...