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Chapter 1. Overview
1-15
Peripheral Logic Overview
1.4.4.3 Byte Ordering
The MPC8240 allows the processor to run in either big- or little-endian mode (except for
the initial boot code which must run in big-endian mode).
1.4.4.4 PCI Agent Capability
In certain applications, the embedded system architecture dictates that the MPC8240 act as
a peripheral processor. In this case, the peripheral logic must not act like a host bridge for
the PCI bus. Instead it functions as a configurable device that is accessed by a host bridge.
This capability allows multiple MPC8240 devices to coexist with other PCI peripheral
devices on a single PCI bus. The MPC8240 has PCI 2.1- compliant configuration
capabilities.
1.4.5 DMA Controller
The integrated DMA controller contains two independent units. Note that the DMA writing
capability for local memory is available for DRAM and SDRAM, but writing is not
available for the ROM/Port X interface. Each DMA unit is capable of performing the
following types of transfers:
•
PCI-to-local memory
•
Local-to-PCI memory
•
PCI-to-PCI memory
•
Local-to-local memory
The DMA controller allows chaining through local memory-mapped chain descriptors.
Transfers can be scatter-gathered and misaligned. Interrupts are provided on completed
segment, chain, and error conditions.
1.4.6 Message Unit (MU)
Many embedded applications require handshake algorithms to pass control, status, and data
information from one owner to another. This is made easier with doorbell and message
registers. The MPC8240 has a message unit (MU) that implements doorbell and message
registers as well as an I
2
O interface. The MU has many conditions that can cause interrupts,
and it uses the EPIC unit to signal external interrupts to the PCI interface and internal
interrupts to the processor core.
1.4.6.1 Doorbell Registers
The MPC8240 MU contains one 32-bit inbound doorbell register and one 32-bit outbound
doorbell register. The inbound doorbell register allows a remote processor to set a bit in the
register from the PCI bus. This, in turn, generates an interrupt to the processor core.
The processor core can write to the outbound register, causing the outbound interrupt signal
INTA to assert, thus interrupting a host processor on PCI. When INTA is generated, it can
be cleared only by the host processor by writing ones to the bits that are set in the outbound
doorbell register.
Содержание MPC8240
Страница 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Страница 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Страница 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Страница 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Страница 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Страница 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Страница 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Страница 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Страница 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Страница 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Страница 516: ...16 14 Watchpoint Trigger Applications ...
Страница 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Страница 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Страница 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...