MC68340 datasheet(397/441 Pages) FREESCALE

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10-10

MC68340 USER’S MANUAL

MOTOROLA

10.2.4 Interfacing an 8-Bit Device to 16-Bit Memory Using Single-

Address DMA Mode

One of the requirements of single-address mode is that the source and destination must

be the same port size. However, the MC68340 can perform direct memory accesses in

single-address mode between an 8-bit device and 16-bit memory. The port size must be

specified as 8 bits, and some external logic is required as shown in Figure 10-14.

DEVICE

74F245

T/R

MC68340

MEMORY

D15-D8

SIZ0

SIZ1

R/W

D7-D0

Figure 10-14. Circuitry for Interfacing 8-Bit Device to

16-Bit Memory in Single-Address DMA Mode

During even-byte accesses, the data is transferred directly on D15–D8. However, during

odd-byte accesses, the data must be routed on D15–D8 for the 8-bit device and on D7–

D0 for the 16-bit memory.

10.3 POWER CONSUMPTION CONSIDERATIONS

The MC68340 can be designed into low-power applications that involve high-performance

processing capability (32-bits), high functional density, small size, portable capability, and

battery operation.

The MC68340 fits into the following types of applications:

• "Palmtop" Computers

• Telephony

— Stylus Input

— Cordless Phones

— Voice Input

— Cellular Phones

— Image Input

• CD-I, CD-ROM

• Transaction Tracking

• Defense Industry

— Car Rental

— Guidance Systems

— Cargo

— Tracking Systems

— Courier

• Data Entry

— Handheld

• Instruments

• Bar Code Scanners

• Handheld Games

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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