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MOTOROLA
MC68306 USER'S MANUAL
3- 5
strobe. When the A0 bit equals zero,
UDS
is asserted; when the A0 bit equals one,
LDS
is
asserted.
The word write cycle flowchart is shown in Figure 3-5. The byte write cycle flowchart is
shown in Figure 3-6. The word and byte write cycle timing is shown in Figure 3-7.
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 D15–D0
6) ASSERT UPPER DATA STROBE (UDS)
AND LOWER DATA STROBE (LDS)
TERMINATE THE CYCLE
INPUT THE DATA
1) DECODE ADDRESS
2) LATCH DATA ON D15–D0
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
SLAVE
START NEXT CYCLE
1) NEGATE DTACK
TERMINATE OUTPUT TRANSFER
1) NEGATE UDS AND LDS
2) NEGATE AS
3) REMOVE DATA FROM D15–D0
4) SET R/W TO READ
Figure 3-5. Word Write Cycle Flowchart