Hold Arbitration - Fujitsu FR60 Hardware Manual

CHAPTER 14 DMA CONTROLLER (DMAC)

14.3.8 Hold Arbitration

When a device is operating in external bus extended mode, an external hold function
can be used. The relationship between external hold requests and DMA transfer
requests by this module when the hold function can be used is described below.
■ DMA Transfer Request during External Hold
DMA transfer is started when an external bus area is accessed, DMA transfer is temporarily
stopped. When the external hold is released, DMA transfer is restarted.
■ External Hold Request during DMA Transfer
The device is externally held. When an external bus area is accessed by DMA transfer, DMA
transfer is temporarily stopped. When the external hold is released, DMA transfer is restarted.
■ Simultaneous Occurrence of a DMA Transfer Request and an External Hold Request
The device is externally held and internal DMA transfer is started. When an external bus area is
accessed by DMA transfer, DMA transfer is temporarily stopped. When the external hold is
released, DMA transfer is restarted.
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