MC68040FE33A Freescale Semiconductor, MC68040FE33A Datasheet - Page 149

• Manufacturer Part Number: MC68040FE33A
• Description: IC MICROPROCESSOR 32BIT 184-CQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68040FE33A

• Processor Type: M680x0 32-Bit
• Speed: 33MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 184-CQFP
• Package: 184CQFP
• Processor Series: M680xx
• Core: CPU32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Details

Figure 7-5 illustrates the transfer of a long-word operand from an odd address requiring
more than one bus cycle. For the first transfer or bus cycle, the SIZx signals specify a byte
transfer, and the byte offset is $1. The slave device supplies the byte and acknowledges
the data transfer. When the processor starts the second cycle, the SIZx signals specify a
word transfer with a byte offset of $2. The next two bytes are transferred during this cycle.
The processor then initiates the third cycle, with the SIZEx signals indicating a byte
transfer. The byte offset is now $0; the port supplies the final byte and the operation is
complete. This example is similar to the one illustrated in Figure 7-6 except that the
operand is word sized and the transfer requires only two bus cycles. Figure 7-7 illustrates
a functional timing diagram for a misaligned long-word read transfer.
MOTOROLA
31
31
31
31
BYTE 0
BYTE 0
BYTE 0
BYTE 0
XXX
—
—
XXX
—
Figure 7-5. Example of a Misaligned Long-Word Transfer
Figure 7-6. Example of a Misaligned Word Transfer
24 23
24 23
24 23
24 23
Freescale Semiconductor, Inc.
For More Information On This Product,
BYTE 3
BYTE 3
XXX
XXX
XXX
—
—
—
—
Go to: www.freescale.com
M68040 USER’S MANUAL
DATA BUS
DATA BUS
MEMORY
MEMORY
16 15
16 15
16 15
16 15
BYTE 2
BYTE 2
XXX
XXX
XXX
—
—
—
—
8 7
8 7
8 7
8 7
BYTE 1
BYTE 1
BYTE 1
BYTE 1
BYTE 1
XXX
XXX
—
X
0
0
0
0
TRANSFER 1
TRANSFER 2
TRANSFER 3
TRANSFER 1
TRANSFER 2
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