Hi Rurik, maybe you already know this, but there is some useful jtag debugging info from Xilinx at:
http://www.xilinx.com/itp/3_1i/pdf/docs/jtg/jtg.pdf In particular, this note explains the difference between hi-z and bypass modes for noise immunity in multi-device jtag chains. Next time it fails, check the state of the TDO pins with a voltmeter to verify they are not stuck low. Best Regards, Oren > Hi everyone, > > We've been experiencing issues with hanging serial ports when > reprogramming > our iBob's over JTAG. Our setup at the moment is a linux control computer > with an 8-port serial-PCI card with two iBob's attached and four iBob's > total on a JTAG chain (the first two being the serial-linked ones). > Programming works just fine and from a cold start so does serial > communication usually. > > The problem occurs when we reprogram a board with a *different* bitstream, > the serial port hangs permanently until the iBob's are power cycled and > reprogrammed. Programming the same bitstream typically does not break the > port. Occasionally however even the power-cycling and reprogramming does > not > bring back the serial ports. It does not seem to be the specific designs > because they usually work after this procedure, instead it seems to be > linked to the reprogramming. > > Has anyone seen this behavior before, or something similar to it? It > appears > to me that during an iBob reprogramming some pin that controls the serial > port fails to go low but perhaps it's a linux multi-serial port problem? > > Thanks for your help! > Rurik > -- Oren Milgrome University of California - Berkeley Radio Astronomy Lab 601 Campbell Hall Berkeley, CA 94720-3411 mobile: 510 368 6857 office: 510 642 5509 lab: 510 642 0381 fax: 510 642 3411 email: [email protected]
