MC68HC000EI20 Freescale Semiconductor, MC68HC000EI20 Datasheet - Page 33

• Manufacturer Part Number: MC68HC000EI20
• Description: IC MPU 16BIT 20MHZ 68-PLCC
• Manufacturer: Freescale Semiconductor

Specifications of MC68HC000EI20

• Processor Type: M680x0 32-Bit
• Speed: 20MHz
• Voltage: 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 68-PLCC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

Data Strobe (
Data Transfer Acknowledge (
3.4 BUS ARBITRATION CONTROL
The bus request, bus grant, and bus grant acknowledge signals form a bus arbitration
circuit to determine which device becomes the bus master device. In the 48-pin version of
the MC68008 and MC68EC000, no pin is available for the bus grant acknowledge signal;
this microprocessor uses a two-wire bus arbitration scheme. All M68000 processors can
use two-wire bus arbitration.
MOTOROLA
This three-state signal and R/W control the flow of data on the data bus of the
MC68008. Table 3-2 lists the combinations of these signals and the corresponding data
on the bus. When the R/W line is high, the processor reads from the data bus. When
the R/W line is low, the processor drives the data bus.
This input signal indicates the completion of the data transfer. When the processor
recognizes DTACK during a read cycle, data is latched, and the bus cycle is terminated.
When DTACK is recognized during a write cycle, the bus cycle is terminated.
DS
*These conditions are a result of current implementation and may not appear
on future devices.
) (MC68008)
M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
High
High
High
UDS
Low
Low
Low
Low
Table 3-1. Data Strobe Control of Data Bus
Freescale Semiconductor, Inc.
DS
1
0
0
For More Information On This Product,
High
High
High
LDS
Low
Low
Low
Low
Table 3-2. Data Strobe Control
DTACK
R/
of Data Bus (MC68008)
—
Go to: www.freescale.com
1
0
W
High
High
High
R/
Low
Low
Low
—
W
).
Valid Data Bits 7–0 (Read Cycle)
Valid Data Bits 7–0 (Write Cycle)
Valid Data Bits
Valid Data Bus
Valid Data Bits
Valid Data Bits
Valid Data Bits
No Valid Data
No Valid Data
D8–D15
No Valid Data
15–8
15–8
15–8
7–0*
15–8
D0–D7
Valid Data Bits
Valid Data Bits
Valid Data Bits
Valid Data Bits
Valid Data Bits
No Valid Data
No Valid Data
D0–D7
15–8*
7–0
7–0
7–0
7–0
3- 5