MC68306FC16 Datasheet, PDF (34/191 Pages) Motorola, Inc – Integrated EC000 Processor

The word read cycle flowchart is shown in Figure 3-1. The byte read cycle flowchart is
shown in Figure 3-2. The read and write cycle timing is shown in Figure 3-3. Figure 3-4
shows the word and byte read cycle timing diagram.
BUS MASTER
ADDRESS THE DEVICE
1) SET R/W TO READ
2) PLACE FUNCTION CODE ON FC2–FC0
3) PLACE ADDRESS ON ADDRESS BUS
4) ASSERT ADDRESS STROBE (AS)
5) ASSERT UPPER DATA STROBE (UDS)
AND LOWER DATA STROBE (LDS)
ACQUIRE THE DATA
1) LATCH DATA
2) NEGATE UDS AND LDS
3) NEGATE AS
SLAVE
OUTPUT THE DATA
1) DECODE ADDRESS
2) PLACE DATA ON D15–D0
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
TERMINATE THE CYCLE
1) REMOVE DATA FROM D15–D0
2) NEGATE DTACK
START NEXT CYCLE
Figure 3-1. Word Read Cycle Flowchart
BUS MASTER
ADDRESS THE DEVICE
1) SET R/W TO READ
2) PLACE FUNCTION CODE ON FC2–FC0
3) PLACE ADDRESS ON ADDRESS BUS
4) ASSERT ADDRESS STROBE (AS)
5) ASSERT UPPER DATA STROBE (UDS)
OR LOWER DATA STROBE (LDS)
(BASED ON A0)
ACQUIRE THE DATA
1) LATCH DATA
2) NEGATE UDS AND LDS
3) NEGATE AS
START NEXT CYCLE
SLAVE
OUTPUT THE DATA
1) DECODE ADDRESS
2) PLACE DATA ON D7–D0 OR D15–D8
(BASED ON UDS OR LDS)
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
TERMINATE THE CYCLE
1) REMOVE DATA FROM D7–D0
OR D15–D8
2) NEGATE DTACK
Figure 3-2. Byte Read Cycle Flowchart
3-2
MC68306 USER'S MANUAL
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