Motorola MCF5282 ユーザーズマニュアル
13-2
MCF5282 User’s Manual
MOTOROLA
Bus Characteristics
13.3 Bus Characteristics
The MCF5282 uses its system clock to generate CLKOUT. Therefore, the external bus
operates at the same speed as the bus clock rate, where all bus operations are synchronous
to the rising edge of CLKOUT, and some of the bus control signals (BS, OE, and CSn,) are
synchronous to the falling edge, shown in Figure 13-1. Bus characteristics may differ
somewhat for interfacing with external DRAM.
operates at the same speed as the bus clock rate, where all bus operations are synchronous
to the rising edge of CLKOUT, and some of the bus control signals (BS, OE, and CSn,) are
synchronous to the falling edge, shown in Figure 13-1. Bus characteristics may differ
somewhat for interfacing with external DRAM.
Figure 13-1. Signal Relationship to CLKOUT for Non-DRAM Access
13.4 Data Transfer Operation
Data transfers between the MCF5282 and other devices involve the following signals:
• Address bus (A[23:0])
• Data bus (D[31:0])
• Control signals (TS and TA)
• CSn, OE, BS
• Attribute signals (R/W, SIZ, and TIP)
• Data bus (D[31:0])
• Control signals (TS and TA)
• CSn, OE, BS
• Attribute signals (R/W, SIZ, and TIP)
TA
Transfer acknowledge
I
Rising
TIP
Transfer in progress
O
Rising
TS
Transfer start
O
Rising
1
These signals change after the falling edge. In the Electrical Specifications, these signals
are specified off of the rising edge because CLKIN is squared up internally.
are specified off of the rising edge because CLKIN is squared up internally.
Table 13-1. ColdFire Bus Signal Summary (Continued)
Signal Name
Description
I/O
CLKOUT Edge
Rising-Edge
Signals
Falling-Edge
Signals
Inputs
t
vo
t
ho
t
vo
t
ho
t
si
t
hi
CLKOUT
t
vo
= Propagation delay of signal relative to CLKOUT edge
t
ho
= Output hold time relative to CLKOUT edge
t
si
= Required input setup time relative to CLKOUT edge
t
hi
= Required input hold time relative to CLKOUT edge