External Bus Interface
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
13-37
Figure 13-28. Reservation on Multilevel Bus Hierarchy
In this case, the buses’ interface block implements a reservation flag for the local bus master. The
reservation flag is set by the buses’ interface when a load with the local bus master issues a reservation
whose address is on the remote bus. The flag is reset when an alternative master on the remote bus accesses
the same location in a write cycle. If the MPC885 begins a memory cycle to the previously reserved
address (located in the remote bus) as a result of a stwcx., the following two cases can occur:
•
If the reservation flag is set, the local bus interface acknowledges the cycle in a normal way.
•
If the reservation flag is reset, the local bus interface should assert KR. However, the local bus
interface should either not perform the remote bus write access or abort it if the remote bus supports
aborted cycles. The failure of stwcx. is reported to the core.
13.4.10 Bus Exception Control Cycles
The MPC885 bus architecture requires assertion of the TA from an external device to signal that the bus
cycle is complete. TA is not asserted in the following cases:
•
the external device does not respond
•
various other application-dependent errors occur
External circuitry or the internal MPC885 bus monitor can provide TEA when no device responds by
asserting TA within an appropriate period of time after the MPC885 initiates the bus cycle. This allows the
cycle to terminate and the processor to enter exception processing for the error condition (each one of the
internal masters causes an internal interrupt under this situation).
To properly control termination of a bus cycle for a bus error, TEA must be asserted at the same time or
before TA is asserted. When TEA is sampled as asserted, it should be negated before the next rising edge
to avoid influencing the next initiated bus cycle. TEA is an open-drain pin that allows the wire-OR of
different sources of error generation.
External Bus (Local Bus)
External Bus
Interface
Master in the Remote
Bus Write to the
AT[0:3], RSV,
KR
S
R
Q
Reserved Location
Buses’
Interface
R/W, TS
Remote Bus
MPC885
A[:31]
Содержание PowerQUICC MPC870
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Страница 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Страница 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Страница 192: ...MPC885 Instruction Set MPC885 PowerQUICC Family Reference Manual Rev 2 5 22 Freescale Semiconductor ...
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Страница 440: ...Clocks and Power Control MPC885 PowerQUICC Family Reference Manual Rev 2 14 24 Freescale Semiconductor ...
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Страница 606: ...SDMA Channels and IDMA Emulation MPC885 PowerQUICC Family Reference Manual Rev 2 19 20 Freescale Semiconductor ...
Страница 738: ...SCC Asynchronous HDLC Mode and IrDA MPC885 PowerQUICC Family Reference Manual Rev 2 25 16 Freescale Semiconductor ...
Страница 780: ...SCC Ethernet Mode MPC885 PowerQUICC Family Reference Manual Rev 2 27 24 Freescale Semiconductor ...
Страница 794: ...SCC Transparent Mode MPC885 PowerQUICC Family Reference Manual Rev 2 28 14 Freescale Semiconductor ...
Страница 848: ...Serial Peripheral Interface SPI MPC885 PowerQUICC Family Reference Manual Rev 2 30 18 Freescale Semiconductor ...
Страница 882: ...Universal Serial Bus USB MPC885 PowerQUICC Family Reference Manual Rev 2 31 34 Freescale Semiconductor ...
Страница 944: ...Parallel I O Ports MPC885 PowerQUICC Family Reference Manual Rev 2 34 26 Freescale Semiconductor ...
Страница 956: ...CPM Interrupt Controller MPC885 PowerQUICC Family Reference Manual Rev 2 35 12 Freescale Semiconductor ...
Страница 1004: ...Buffer Descriptors and Connection Tables MPC885 PowerQUICC Family Reference Manual Rev 2 37 30 Freescale Semiconductor ...
Страница 1022: ...ATM Parameter RAM MPC885 PowerQUICC Family Reference Manual Rev 2 38 18 Freescale Semiconductor ...
Страница 1068: ...ATM Pace Control MPC885 PowerQUICC Family Reference Manual Rev 2 40 22 Freescale Semiconductor ...
Страница 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Страница 1120: ...AAL2 Implementation MPC885 PowerQUICC Family Reference Manual Rev 2 44 30 Freescale Semiconductor ...
Страница 1162: ...Fast Ethernet Controller FEC MPC885 PowerQUICC Family Reference Manual Rev 2 45 40 Freescale Semiconductor ...
Страница 1172: ...SEC Lite Overview MPC885 PowerQUICC Family Reference Manual Rev 2 46 8 Freescale Semiconductor ...
Страница 1176: ...SEC Lite Address Map MPC885 PowerQUICC Family Reference Manual Rev 2 47 4 Freescale Semiconductor ...
Страница 1214: ...SEC Lite Execution Units MPC885 PowerQUICC Family Reference Manual Rev 2 48 38 Freescale Semiconductor ...
Страница 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Страница 1313: ...MPC885 PowerQUICC Family Reference Manual Rev 2 Freescale Semiconductor B 1 Appendix B Serial Communications Performance TBD ...
Страница 1314: ...Serial Communications Performance MPC885 PowerQUICC Family Reference Manual Rev 2 B 2 Freescale Semiconductor ...
Страница 1320: ...Register Quick Reference Guide MPC885 PowerQUICC Family Reference Manual Rev 2 C 6 Freescale Semiconductor ...
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Страница 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Страница 1384: ...Serial ATM Scrambling Reception and SI Programming MPC885 PowerQUICC Family Reference Manual Rev 2 H 6 Freescale Semiconductor ...
Страница 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...