MC68EC020AA25 Freescale Semiconductor, MC68EC020AA25 Datasheet - Page 67

• Manufacturer Part Number: MC68EC020AA25
• Description: IC MPU 32BIT 25MHZ 100-QFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68EC020AA25

• Processor Type: M680x0 32-Bit
• Speed: 25MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 100-QFP
• Family Name: M68000
• Device Core: ColdFire
• Device Core Size: 32b
• Frequency (max): 25MHz
• Instruction Set Architecture: RISC
• Supply Voltage 1 (typ): 5V
• Operating Supply Voltage (max): 5.25V
• Operating Supply Voltage (min): 4.75V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 100
• Package Type: PQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

5.2.3 Effects of Dynamic Bus Sizing and Operand Misalignment
The combination of operand size, operand alignment, and port size determine the number
of bus cycles required to perform a particular memory access. Table 5-6 lists the number
of bus cycles required for different operand sizes to different port sizes with all possible
alignment conditions for read/write cycles.
Table 5-6 reveals that bus cycle throughput is significantly affected by port size and
alignment. The MC68020/EC020 system designer and programmer should be aware of
and account for these effects, particularly in time-critical applications.
5-20
31
D31
OP0
MSB
OP1
XXX
*
Instruction prefetches are always two words from a long-word boundary
Instruction
Byte Operand
Word Operand
Long-Word Operand
Figure 5-17. Misaligned Long-Word Operand Read
LONG-WORD OPERAND (REGISTER)
Operand Size
OP1
UMB
OP2
Table 5-6. Memory Alignment and Port Size
XXX
LONG-WORD MEMORY
*
Influence on Read/Write Bus Cycles
DATA BUS
from Long-Word Port Example
M68020 USER’S MANUAL
LMB
XXX
OP3
OP2
1:2:4
1:1:2
1:2:4
1:1:1
(Data Port Size = 32 Bits:16 Bits:8 Bits)
00
Number of Bus Cycles
OP0
LSB
XXX
OP3
1:1:1
1:2:2
2:3:4
N/A
01
A1, A0
D0
0
SIZ1 SIZ0 A2
0
1
1:1:1
1:1:2
2:2:4
N/A
10
MC68020/EC020
0
1
0
1
A1
1:1:1
2:2:2
2:3:4
1
0
N/A
11
A0
1
0
MEMORY CONTROL
DSACK1
L
L
MOTOROLA
DSACK0
L
L