NOTE: This is more of a curiosity than an actual problem.
This weekend I discovered some strange behavior after reconfiguration of a xc2vp30. Upon power-up of the board (an ml310), I can use Impact to program the device with no problems. However, if I then reconfigure the device with certain other bitstreams w/o powering down first, impact claims it programs successfully but the device does not start running. I can attempt to connect to my non-running EDK design on the device using XMD -- if the design was MicroBlaze-based XMD connects but displays all zeros for memory and registers locations; if the design was PPC-based XMD returns the error: "ERROR: Unable to connect to PowerPC target. Invalid Processor Version No 0x00000000". Again, these bitstreams that fail to run work perfectly if I first power down the device.
In searching for a solution, I came across this Answer Record
I had thought, however, that the program pin got pulsed before every reconfiguration. What then does selecting "Pulse program pin" do, and why does it fix my problem? (For that matter, does anyone know why I had a problem to begin with?)
Thanks! Stephen