4- 4 M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL MOTOROLA
BUS MASTER
ADDRESS THE DEVICE
1) PLACE FUNCTION CODE ON FC2–FC0
2) PLACE ADDRESS ON A23–A0
3) ASSERT ADDRESS STROBE (AS)
4) SET R/W TO WRITE
5) PLACE DATA ON D0–D7
6) ASSERT LOWER DATA STROBE (LDS)
OR DS
1) NEGATE LDS OR DS
2) NEGATE AS
3) REMOVE DATA FROM D7-D0
4) SET R/W TO READ
TERMINATE THE CYCLE
INPUT THE DATA
1) DECODE ADDRESS
2) STORE DATA ON D7–D0
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
SLAVE
START NEXT CYCLE
TERMINATE OUTPUT TRANSFER
1) NEGATE DTACK
Figure 4-3. Byte Write-Cycle Flowchart
S0 S1 S2 S3 S4 S5 S6 S7 S0 S1 S2 S3 S4 S5 S6 S7 S0 S1 S2 S3 S4 S5 S6 S7
CLK
FC2–FC0
A23–A0
AS
LDS
R/W
DTACK
D7–D0
EVEN BYTE WRITE
ODD BYTE WRITE ODD BYTE WRITE
Figure 4-4. Write-Cycle Timing Diagram
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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