Figure 3-1. Word Read Cycle Flowchart; Figure 3-2. Byte Read Cycle Flowchart - Motorola MC68306 User Manual

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
START NEXT CYCLE
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
3-2

Figure 3-1. Word Read Cycle Flowchart

Figure 3-2. Byte Read Cycle Flowchart

MC68306 USER'S MANUAL
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
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
MOTOROLA