For each XINTF access, the number of lead, active, and trail cycles is based on the internal clock XTIMCLK. Strobes such as XRD, XWE0, XWE1, and zone chip-select ( XZCS) change state in relationship to the rising edge of XTIMCLK. The external clock, XCLKOUT, can be configured to be either equal to or one-half the frequency of XTIMCLK.

For the case where XCLKOUT = XTIMCLK, all of the XINTF strobes will change state with respect to the rising edge of XCLKOUT. For the case where XCLKOUT = one-half XTIMCLK, some strobes will change state either on the rising edge of XCLKOUT or the falling edge of XCLKOUT. In the XINTF timing tables, the notation XCOHL is used to indicate that the parameter is with respect to either case; XCLKOUT rising edge (high) or XCLKOUT falling edge (low). If the parameter is always with respect to the rising edge of XCLKOUT, the notation XCOH is used.

For the case where XCLKOUT = one-half XTIMCLK, the XCLKOUT edge with which the change will be aligned can be determined based on the number of XTIMCLK cycles from the start of the access to the point at which the signal changes. If this number of XTIMCLK cycles is even, the alignment will be with respect to the rising edge of XCLKOUT. If this number is odd, then the signal will change with respect to the falling edge of XCLKOUT. Examples include the following:

• Strobes that change at the beginning of an access always align to the rising edge of XCLKOUT. This is because all XINTF accesses begin with respect to the rising edge of XCLKOUT.

  	Examples:	XZCSL	Zone chip-select active low
  		XRNWL	XR/ W active low

• Strobes that change at the beginning of the active period will align to the rising edge of XCLKOUT if the total number of lead XTIMCLK cycles for the access is even. If the number of lead XTIMCLK cycles is odd, then the alignment will be with respect to the falling edge of XCLKOUT.

  	Examples:	XRDL	XRD active low
  		XWEL	XWE1 or XWE0 active low

• Strobes that change at the beginning of the trail period will align to the rising edge of XCLKOUT if the total number of lead + active XTIMCLK cycles (including hardware wait states) for the access is even. If the number of lead + active XTIMCLK cycles (including hardware wait states) is odd, then the alignment will be with respect to the falling edge of XCLKOUT.

  	Examples:	XRDH	XRD inactive high
  		XWEH	XWE1 or XWE0 inactive high

• Strobes that change at the end of the access will align to the rising edge of XCLKOUT if the total number of lead + active + trail XTIMCLK cycles (including hardware wait states) is even. If the number of lead + active + trail XTIMCLK cycles (including hardware wait states) is odd, then the alignment will be with respect to the falling edge of XCLKOUT.

  	Examples:	XZCSH	Zone chip-select inactive high
  		XRNWH	XR/ W inactive high