13-6
MCF5282 User’s Manual
MOTOROLA
Data Transfer Operation
NOTE:
An external device has at most two CLKOUT cycles after the
start of S4 to three-state the data bus. This applies to basic read
cycles, fast termination cycles, and the last transfer of a burst.
13.4.3 Read Cycle
During a read cycle, the MCF5282 receives data from memory or from a peripheral device.
Figure 13-5 is a read cycle flowchart.
S3
Read/write
(skipped for
fast
termination)
Low
The MCF5282 waits for TA assertion. If TA is not sampled as asserted before the
rising edge of CLKOUT at the end of the first clock cycle, the MCF5282 inserts
wait states (full clock cycles) until TA is sampled as asserted.
Read
Data is made available by the external device on the falling edge of CLKOUT and
is sampled on the rising edge of CLKOUT with TA asserted.
S4
All
High
The external device should negate TA.
Read
(including
fast-terminat
ion)
The external device can stop driving data after the rising edge of CLKOUT.
However data could be driven through the end of S5.
S5
S5
Low
CS, BS, and OE are negated on the CLKOUT falling edge of S5. The MCF5282
stops driving address lines and R/W on the rising edge of CLKOUT, terminating
the read or write cycle. At the same time, the MCF5282 negates TIP, and SIZ[1:0]
on the rising edge of CLKOUT.
Note that the rising edge of CLKOUT may be the start of S0 for the next access
cycle.
Read
The external device stops driving data between S4 and S5.
Write
The data bus returns to high impedance on the rising edge of CLKOUT. The
rising edge of CLKOUT may be the start of S0 for the next access.
Table 13-3. Bus Cycle States (Continued)
State
Cycle
CLKOUT
Description
Summary of Contents for ColdFire MCF5281
Page 124: ...3 20 MCF5282 User s Manual MOTOROLA EMAC Instruction Set Summary ...
Page 141: ...MOTOROLA Chapter 5 Static RAM SRAM 5 5 SRAM Programming Model ...
Page 142: ...5 6 MCF5282 User s Manual MOTOROLA SRAM Programming Model ...
Page 168: ...6 26 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 186: ...7 18 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 228: ...9 22 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 246: ...10 18 MCF5282 User s Manual MOTOROLA Low Power Wakeup Operation ...
Page 254: ...11 8 MCF5282 User s Manual MOTOROLA Memory Map and Registers ...
Page 264: ...12 10 MCF5282 User s Manual MOTOROLA Chip Select Registers ...
Page 280: ...13 16 MCF5282 User s Manual MOTOROLA Misaligned Operands ...
Page 314: ...14 34 MCF5282 User s Manual MOTOROLA MCF5282 External Signals ...
Page 339: ...MOTOROLA Chapter 15 Synchronous DRAM Controller Module 15 25 SDRAM Example ...
Page 340: ...15 26 MCF5282 User s Manual MOTOROLA SDRAM Example ...
Page 356: ...16 16 MCF5282 User s Manual MOTOROLA DMA Controller Module Functional Description ...
Page 408: ...17 52 MCF5282 User s Manual MOTOROLA Buffer Descriptors ...
Page 446: ...20 24 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 474: ...22 18 MCF5282 User s Manual MOTOROLA Programming Model ...
Page 510: ...23 36 MCF5282 User s Manual MOTOROLA Operation ...
Page 526: ...24 16 MCF5282 User s Manual MOTOROLA I2C Programming Examples ...
Page 672: ...28 12 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 718: ...29 46 MCF5282 User s Manual MOTOROLA Motorola Recommended BDM Pinout ...
Page 750: ...32 8 MCF5282 User s Manual MOTOROLA Ordering Information ...