mcf5407 Freescale Semiconductor, Inc, mcf5407 Datasheet - Page 430

• Manufacturer Part Number: mcf5407
• Description: Mcf5407 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

1
Bus Characteristics
18.3 Bus Characteristics
The MCF5407 uses an input clock signal (CLKIN) to generate its internal clock and
outputs BCLKO, which is provided for backwards compatibility for MCF5307 designs.
CLKIN is the bus clock rate, where all bus operations are synchronous to the rising edge of
CLKIN. Some of the bus control signals (BE/BWE, OE, CSx, and AS) are synchronous to
the falling edge, shown in Figure 18-1. Bus characteristics may differ somewhat for
interfacing with external DRAM.
18.4 Data Transfer Operation
Data transfers between the MCF5407 and other devices involve the following signals:
18-2
These signals change after the falling edge. In Chapter 20, “Electrical Specifications,” these signals are specified
off the rising edge because CLKIN is squared up internally.
Falling-Edge
Rising-Edge
Signal Name
IRQ[7,5,3,1]
SIZ[1:0]
TM[2:0]
TT[1:0]
Signals
Signals
OE
R/W
CLKIN
TIP
TS
Inputs
t
t
t
t
TA
vo
ho
si
hi
=Required input setup time relative to CLKIN edge
=Required input hold time relative to CLKIN edge
=Propagation delay of signal relative to CLKIN edge
=Output hold time relative to CLKIN edge
1
Figure 18-1. Signal Relationship to CLKIN for Non-DRAM Access
Table 18-1. ColdFire Bus Signal Summary (Continued)
Interrupt request
Output enable
Read/write
Transfer size
Transfer acknowledge
Transfer in progress
Transfer modifier
Transfer start
Transfer type
Description
t
si
t
t
vo
hi
MCF5407 User’s Manual
I
O
O
O
I
O
O
O
O
MCF5407 Master
t
vo
I
I
I
I
O
Three-state
Three-state
I
Three-state
External Master
t
ho
Rising
Falling
Rising
Rising
Rising
Rising
Rising
Rising
Rising
Edge
t
ho