xapp138(Virtex):

The Start-up Sequencer is an 8-phase sequential state machine that transitions from phase 0 to phase 7.

The Start-up Sequencer performs the following tasks:
1. Releases the DONE pin.
2. Negates GTS, activating all the I/Os.
3. Asserts GWE, allowing all RAMs and flip-flops to change state (flip-   flops cannot change state while GSR is asserted).
4. Negates GSR, allowing all flip-flops to change state.
5. Asserts EOS. The End-Of-Start-up flag is always set in phase 7.     This is an internal flag that is not user accessible.

 

After a shutdown sequence has been performed, all user logic and I/O is disabled until a start-up sequence is performed. The shut-down sequence is enabled by setting bit 15 of the COR.

 

 

After the completion of the readback session, a Start-up Sequence must be performed to reactivate the user logic and I/O. To enable the start-up, the shut-down bit (15) of the COR must be reset to a logic 0. Then, just as with the Shut-down Sequence, the START and RCRC commands must be loaded into the CMD register and the Sequence must be clocked eight times, at which time the device may resume normal operation.

 

Xapp139(Virtex):

JSTART:Clocks the start-up sequence when StartClk is TCK.

 

Xapp151(Virtex):

CMD--START:Begin Startup Sequence — Starts the startup sequence. This command is also used to start a shutdown sequence prior to partial re-configuration. The Startup Sequence begins with the next
successful CRC check (see Cyclic Redundancy Check (CRC), page 21).

COR第15位是1表shutdown sequence ，0表startup sequence。

 

xapp176与xapp138相似，176是spartan2系列，138是virtex系列。