ADSP-21266_07 AD [Analog Devices], ADSP-21266_07 Datasheet - Page 27

• Manufacturer Part Number: ADSP-21266_07
• Description: Embedded Processor
• Manufacturer: AD [Analog Devices]

Memory Write—Parallel Port
Use the specifications in
Figure 21
memory-mapped peripherals) when the ADSP-21266 is access-
ing external memory space.
Table 24. 8-Bit Memory Write Cycle
1
Parameter
Switching Characteristics
t
t
t
t
t
t
t
t
t
t
t
D = (The value set by the PPDUR Bits (5–1) in the PPCTL register) × t
H = t
On reset, ALE is an active high cycle. However, it can be reconfigured by software to be active low.
ALEW
ALERW
ADAS
ADAH
WW
ADWL
ADWH
ALEHZ
DWS
DWH
DAWH
1
1
CCLK
(if a hold cycle is specified, else H = 0)
for asynchronous interfacing to memories (and
AD15-8
AD7-0
ALE
ALE Pulse Width
ALE Deasserted to Read/Write Asserted
Address/Data 15–0 Setup Before ALE Deasserted
Address/Data 15–0 Hold After ALE Deasserted
WR Pulse Width
Address/Data 15–8 to WR Low
Address/Data 15–8 Hold After WR High
ALE Deasserted to Address/Data 15–0 in High-Z
Address/Data 7–0 Setup Before WR High
Address/Data 7–0 Hold After WR High
Address/Data to WR High
WR
RD
Table
24,
Table
VALID ADDRESS
VALID ADDRESS
25,
t
ADAS
t
ALEW
Figure
Rev. C | Page 27 of 44 | October 2007
20, and
Figure 20. 8-Bit Memory Write Cycle
t
ADAH
t
ALEHZ
t
ALERW
CCLK
t
ADWL
VALID ADDRESS
t
DAW H
Min
2 × t
1 × t
2.5 × t
0.5 × t
D – 2
0.5 × t
0.5 × t
0.5 × t
D
0.5 × t
D
t
WW
CCLK
CCLK
VALID DATA
CCLK
CCLK
CCLK
CCLK
CCLK
CCLK
t
DWS
– 2
– 0.5
– 2.0
– 0.8
– 1.5
– 1 + H
– 0.8
– 1.5 + H
t
DWH
t
ADWH
Max
0.5 × t
CCLK
ADSP-21266
+ 2.0
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns