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MC68306 USER'S MANUAL
MOTOROLA
BUS MASTER
ADDRESS THE DEVICE
1) PLACE FUNCTION CODE ON FC2–FC0
2) PLACE ADDRESS ON ADDRESS BUS
3) ASSERT ADDRESS STROBE (AS)
4) SET R/W TO WRITE
5) PLACE DATA ON D0–D7 OR D15–D8
(ACCORDING TO INTERNAL A0)
6) ASSERT UPPER DATA STROBE (UDS)
OR LOWER DATA STROBE (LDS)
(BASED ON INTERNAL A0)
1) NEGATE UDS AND LDS
2) NEGATE AS
3) REMOVE DATA FROM D7-D0 OR
D15-D8
4) SET R/W TO READ
TERMINATE THE CYCLE
INPUT THE DATA
1) DECODE ADDRESS
2) LATCH DATA ON D7–D0 IF LDS IS
ASSERTED. LATCH DATA ON D15–D8
IF UDS IS ASSERTED
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
SLAVE
START NEXT CYCLE
TERMINATE OUTPUT TRANSFER
1) NEGATE DTACK
Figure 3-6. 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
*INTERNAL SIGNAL ONLY
A0
*
CLK
FC2–FC0
A31–A1
AS
UDS
LDS
R/W
DTACK
D15–D8
D7–D0
EVEN BYTE WRITE
WORD WRITE
ODD BYTE WRITE
Figure 3-7. Word and Byte Write Cycle Timing Diagram