Infineon Technologies TC1784, Руководство пользователя

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TC1784
On-Chip System Buses and Bus Bridges
User´s Manual 4-26 V1.1, 2011-05
Buses, V1.9
4.6 FPI Bus Control Unit (SBCU)
The TC1784 incorporates one BCU for the SPB, called SBCU.
4.6.1 FPI Bus Arbitration
The arbitration unit of the BCU determines whether it is necessary to arbitrate for FPI
Bus ownership, and, if so, which available bus requestor gets the FPI Bus for the next
data transfer. During arbitration, the bus is granted to the requesting agent with the
highest priority. If no request is pending, the bus is granted to a default master. If no bus
master takes the bus, the BCU itself will drive the FPI Bus to prevent it from floating
electrically.
4.6.1.1 Arbitration on the System Peripheral Bus
The TC1784 SPB has three bus agents that can become a SPB bus master (DMA, LFI,
PCP). Each agent is supplied an arbitration priority as shown in
Table 4-9 . DMA
controller agent can be assigned to low, medium or high priority by software (via DMA
Channel and OCDS control registers).
Table 4-9 Priority of TC1784 SPB Bus Agents
Priority Agent Comment
highest
lowest
Any bus requestor meeting the
starvation protection criteria is assigned
this priority Highest priority, used only for
starvation protection
DMA, high priority DMA requests from module:
- OCDS high priority
1)
- DMA channel with high priority
2)
1) Priority of Cerberus transaction at the On Chip Busses is defined by the register bit IOCONF.FPI_PRIO. The
register is defined in the OCDS chapter.
2) Priority of a DMA channel is defined by the corresponding CHCRmn.DMAPRIO bits. The registers are defined
in the DMA chapter.
Peripheral Control Processor (PCP) Default master 0
DMA, medium priority DMA requests from module:
- DMA channels with med. priority
LFI Bridge Default master 1
DMA, low priority DMA requests from modules:
- Cerberus low priority
1)
- DMA channels low priority
2)
- MLI