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MC68HC000EI20 Datasheet, PDF (44/189 Pages) Freescale Semiconductor, Inc – 8-/16-/32-Bit Microprocessors User’s Manual | |||
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Freescale Semiconductor, Inc.
BUS MASTER
ADDRESS THE DEVICE
1) SET R/W TO READ
2) PLACE FUNCTION CODE ON FC2âFC0
3) PLACE ADDRESS ON A23âA0
4) ASSERT ADDRESS STROBE (AS)
5) ASSERT LOWER DATA STROBE (LDS)
(DS ON MC68008)
ACQUIRE THE DATA
1) LATCH DATA
1) NEGATE LDS OR DS
2) START DATA MODIFICATION
START OUTPUT TRANSFER
1) SET R/W TO WRITE
2) PLACE DATA ON D7âD0
3) ASSERT LOWER DATA STROBE (LDS)
(DS ON MC68008)
TERMINATE OUTPUT TRANSFER
1) NEGATE DS OR LDS
2) NEGATE AS
3) REMOVE DATA FROM D7âD0
4) SET R/W TO READ
START NEXT CYCLE
SLAVE
INPUT THE DATA
1) DECODE ADDRESS
2) PLACE DATA ON D7âD0
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
TERMINATE THE CYCLE
1) REMOVE DATA FROM D7âD0
2) NEGATE DTACK
INPUT THE DATA
1) STORE DATA ON D7âD0
2) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
TERMINATE THE CYCLE
1) NEGATE DTACK
Figure 4-5. Read-Modify-Write Cycle Flowchart
4-6
M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
MOTOROLA
For More Information On This Product,
Go to: www.freescale.com
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