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DMA Signals: Requestor Interface
MSC8113 Reference Manual, Rev. 0
Freescale Semiconductor
16-3
16.1 DMA Signals: Requestor Interface
A requestor is an external peripheral or an internal request generated by the DMA FIFO. A
peripheral interfaces with the DMA controller by placing a request for service. The request can
be external or internal, depending on its origin.
16.1.1 Signal Functionality
The DMA signals are as follows:
DMA Peripherals Handshake. The DMA handshake to a peripheral uses four peer-to-peer
signals. Normally, peripherals use only a subset of these signals.
— DMA request (
DREQ
). Sent to indicate that the peripheral is requesting DMA service.
When the DMA controller samples it, the DMA controller initiates a transaction on the
bus that services the requesting peripheral.
DREQ
can be configured to work in high or
low level-triggered mode or in rising or falling edge-triggered mode. This signal is
synchronized by the DMA controller and can be driven asynchronously by a
peripheral.
— DMA data acknowledge (
DACK
). Asserted by the DMA controller. Qualification with
the
PSDVAL
signal means that the data phase on the bus is generated by the DMA
controller for the peripheral connected to this
DACK
. It is asserted during the entire data
phase. The transaction is as follows:
•
Write transaction. The peripheral samples the data during
DACK
with the qualifying
PSDVAL
signal.
•
Read transaction. The peripheral drives the data during
DACK
with the qualifying
PSDVAL
signal.
—
DONE.
This bidirectional signal signifies that the channel must be terminated.
•
If the DMA controller generates
DONE
, the channel handling this peripheral is
inactive and the peripheral is not serviced further.
•
As an input to the DMA controller,
DONE
closes the channel, as in normal channel
closing, when the channel size reaches zero. During closing, the FIFOs are emptied
and the ACTV bit in the channel’s configuration register (DCHCR[ACTV]) is
deasserted.
— Data request acknowledge (
DRACK
). The DMA controller asserts this signal to indicate
that it has sampled the peripheral request. The peripheral can deassert its current
request and assert a new request if needed. When a peripheral is using the
DRACK
signal option, it should not assert
DONE
.
Summary of Contents for MSC8113
Page 1: ...MSC8113 Reference Manual Tri Core 16 Bit Digital Signal Processor MSC8113RM Rev 0 May 2008 ...
Page 20: ...MSC8113 Reference Manual Rev 0 xx Freescale Semiconductor Contents ...
Page 28: ...MSC8113 Reference Manual Rev 0 xxviii Freescale Semiconductor ...
Page 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Page 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Page 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Page 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Page 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Page 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Page 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Page 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Page 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Page 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Page 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Page 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Page 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Page 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
Page 1171: ...MSC8113 Reference Manual Rev 0 Freescale Semiconductor C 61 EF wait_rts P 01077FFC 9F rts 71 ...
Page 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
Page 1202: ...MSC8113 Reference Manual Rev 0 Index 30 Freescale Semiconductor Index ...