Motorola DSP96002 User Manual

Page 133

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MOTOROLA

DSP96002 USER’S MANUAL

7 - 47

7.5.3.1

DCS DMA Destination Space Control (DDS2-DDS0) Bits 0,1,2

The DMA Destination Space control bits (DDS2-DDS0) specify the memory or I/O space that will be refer-

enced as destination by the DMA. The DDS2-DDS0 bits are cleared by Hardware and Software Reset.

7.5.3.2

DCS DMA Source Space Control (DSS2-DSS0) Bits 3,4,5

The DMA Source Space control bits (DSS2-DSS0) specify the memory or I/O space that will be referenced

as source by the DMA. The DSS2-DSS0 bits are cleared by Hardware and Software Reset.

7.5.3.3

DCS Reserved Bits (Bits 6, 7, 15-22, 27, 29)

These bits read as zero and should be written with zero for future compatibility.

7.5.3.4

DCS DMA Request Masks (M0-M6) Bits 8-14

The DMA Request mask bits select the source of DMA requests used to trigger DMA transfers. If a mask

bit is set, the corresponding device is selected as the DMA request source. If the mask bit is cleared, the

device is ignored. The DMA request sources may be the internal peripherals or external devices requesting

service through the

—

–

—

–

B and

–

—

–

C pins. The external inputs behave as edge-

triggered synchronous inputs. The mask bits are cleared by Hardware and Software Reset. The internal

DMA request sources are produced by ANDing the internal peripheral status bits with DE.

Each requesting device input is first individually ANDed with its respective mask bit (M0,M1,etc) and then

all AND outputs are ORed together. The OR output goes to the edge-triggered latch whose output initiates

DDS2

DDS1

DDS0

DMA Destination Memory Space

0 0 0 Internal Program Memory

0 0 1 Internal X Data Memory

0 1 0 Internal Y Data Memory

0 1 1 Internal I/O (X Memory Space)

1 0 0 External Program Memory

1 0 1 External X Data Memory

1 1 0 External Y Data Memory

1 1 1 External I/O (Y Memory Space)

DSS2

DSS1 DSS0

DMA Source Memory Space