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Rev. D
|
Page 28 of 56
|
November 2008
ADSP-21367/ADSP-21368/ADSP-21369
Memory Read
Use these specifications for asynchronous interfacing to memo-
ries. These specifications apply when the processors are the bus
master accessing external memory space in asynchronous access
mode. Note that timing for ACK, DATA, RD, WR, and strobe
timing parameters only apply to asynchronous access mode.
Table 25. Memory Read
Parameter
Min
Max
Unit
Timing Requirements
t
DAD
Address, Selects Delay to Data Valid
1
W + t
SDCLK
–5.12
ns
t
DRLD
RD Low to Data Valid
W – 3.2
ns
t
SDS
Data Setup to RD High
2.5
ns
t
HDRH
Data Hold from RD High
2,
3
0
ns
t
DAAK
ACK Delay from Address, Selects
t
SDCLK
– 9.5 + W
ns
t
DSAK
ACK Delay from RD Low
4
W – 7.0
ns
Switching Characteristics
t
DRHA
Address Selects Hold After RD High
RH + 0.20
ns
t
DARL
Address Selects to RD Low
t
SDCLK
– 3.3
ns
t
RW
RD Pulse Width
W – 1.4
ns
t
RWR
RD High to WR, RD Low
HI + t
SDCLK
– 0.8
ns
W = (number of wait states specified in AMICTLx register) × t
SDCLK
.
HI =RHC + IC (RHC = number of read hold cycles specified in AMICTLx register) × t
SDCLK
IC = (number of idle cycles specified in AMICTLx register) × t
SDCLK
.
H = (number of hold cycles specified in AMICTLx register) × t
SDCLK
.
1
The falling edge of MSx is referenced.
2
Note that timing for ACK, DATA, RD, WR, and strobe timing parameters only apply to asynchronous access mode.
3
Data hold: User must meet t
HDA
or t
HDRH
in asynchronous access mode. See
for the calculation of hold times given capacitive and dc loads.
4
ACK delay/setup: User must meet t
DAAK
, or t
DSAK
, for deassertion of ACK (low). For asynchronous assertion of ACK (high), user must meet t
DAAK
or t
DSAK
.
Figure 18. Memory Read
ACK
DATA
t
DARL
t
RW
t
DAD
t
DAAK
t
HDRH
t
RWR
t
DRLD
t
DRHA
t
D
S
AK
t
S
D
S
ADDRE
SS
MSx
RD
WR