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MC68340AB16E Datasheet, PDF (397/441 Pages) Motorola, Inc – Integrated Processor with DMA User’s Manual | |||
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Freescale Semiconductor, Inc.
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
D15-D8
R/W
MC68340 A0
SIZ1
SIZ0
T/R
B
74F245
OE
A
D7-D0
MEMORY
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 D15âD8. However, during
odd-byte accesses, the data must be routed on D15âD8 for the 8-bit device and on D7â
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
â Stylus Input
â Voice Input
â Image Input
⢠Transaction Tracking
â Car Rental
â Cargo
â Courier
â Handheld
⢠Bar Code Scanners
⢠Telephony
â Cordless Phones
â Cellular Phones
⢠CD-I, CD-ROM
⢠Defense Industry
â Guidance Systems
â Tracking Systems
⢠Data Entry
⢠Instruments
⢠Handheld Games
10-10
MC68340 USERâS MANUAL
For More Information On This Product,
Go to: www.freescale.com
MOTOROLA
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