MC68HC000RC12 Datasheet, PDF (40/189 Pages) Freescale Semiconductor, Inc – 8-/16-/32-Bit Microprocessors User’s Manual

Freescale Semiconductor, Inc.
BUS MASTER
ADDRESS THE DEVICE
1) SET R/W TO READ
2) PLACE FUNCTION CODE ON FC2–FC0
3) PLACE ADDRESS ON A23-A0
4) ASSERT ADDRESS STROBE (AS)
5) ASSERT LOWER DATA STROBE (LDS)
(DS ON MC68008)
ACQUIRE THE DATA
1) LATCH DATA
2) NEGATE LDS (DS FOR MC68008)
3) NEGATE AS
START NEXT CYCLE
SLAVE
INPUT THE DATA
1) DECODE ADDRESS
2) PLACE DATA ON D7–D0
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
TERMINATE THE CYCLE
1) REMOVE DATA FROM D7–D0
2) NEGATE DTACK
Figure 4-1. Byte Read-Cycle Flowchart
CLK
FC2–FC0
A23–A0
AS
(DS) LDS
S0 S1 S2 S3 S4 S5 S6 S7 S0 S1 S2 S3 S4 S5 S6 S7 S0 S1 S2 S3 S4 w w w w S5 S6 S7
R/W
DTACK
D7–D0
READ
WRITE
2 WAIT STATE READ
Figure 4-2. Read and Write-Cycle Timing Diagram
4-2
M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
MOTOROLA
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