
Electrical Specifications
113
June 2004
SPRS257
If the XREADY signal is sampled in the Synchronous mode (USEREADY = 1, READYMODE = 0), then:
LR
≥
t
c(XTIM)
LW
≥
t
c(XTIM)
2.
Active:
AR
≥
2 x t
c(XTIM)
AW
≥
2 x t
c(XTIM)
NOTE
: Restriction does not include external hardware wait states
1.
Lead:
These requirements result in the following XTIMING register configuration restrictions
:
XRDLEAD
≥
1
No hardware to detect illegal XTIMING configurations
XRDACTIVE
≥
1
XRDTRAIL
≥
0
XWRLEAD
≥
1
XWRACTIVE
≥
1
XWRTRAIL
≥
0
X2TIMING
0, 1
Examples of valid and invalid timing when using Synchronous XREADY
:
XRDLEAD
0
1
1
XRDACTIVE
0
0
1
XRDTRAIL
0
0
0
XWRLEAD
0
1
1
XWRACTIVE
0
0
1
XWRTRAIL
0
0
0
X2TIMING
0, 1
0, 1
0, 1
Invalid
Invalid
Valid
No hardware to detect illegal XTIMING configurations
If the XREADY signal is sampled in the Asynchronous mode (USEREADY = 1, READYMODE = 1), then:
LR
≥
t
c(XTIM)
LW
≥
t
c(XTIM)
2.
Active:
AR
≥
2 x t
c(XTIM)
AW
≥
2 x t
c(XTIM)
NOTE
: Restriction does not include external hardware wait states
LR + AR
≥
4 x t
c(XTIM)
LW + AW
≥
4 x t
c(XTIM)
NOTE
: Restriction does not include external hardware wait states
1.
Lead:
3.
Lead + Active:
These requirements result in the following XTIMING register configuration restrictions
:
XRDLEAD
≥
1
No hardware to detect illegal XTIMING configurations
or
XRDACTIVE
≥
2
XRDTRAIL
0
XWRLEAD
≥
1
XWRACTIVE
≥
2
XWRTRAIL
0
X2TIMING
0, 1
XRDLEAD
≥
2
No hardware to detect illegal XTIMING configurations
XRDACTIVE
≥
1
XRDTRAIL
0
XWRLEAD
≥
2
XWRACTIVE
≥
1
XWRTRAIL
0
X2TIMING
0, 1
Examples of valid and invalid timing when using Asynchronous XREADY
:
XRDLEAD
0
1
1
1
1
2
XRDACTIVE
0
0
1
1
2
1
XRDTRAIL
0
0
0
0
0
0
XWRLEAD
0
1
1
1
1
2
XWRACTIVE
0
0
1
1
2
1
XWRTRAIL
0
0
0
0
0
0
X2TIMING
0, 1
0, 1
0
1
0, 1
0, 1
Invalid
Invalid
Invalid
Valid
Valid
Valid
No hardware to detect illegal XTIMING configurations
A