http://www.ti.com/sc/docs/jtag/seminar1.pdf - Jim Antonellis jim.antonellis@xxxxxxxxxxxxx Sandburst Corp www.sandburst.com (978) 689-1669 -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Trey Henderson Sent: Tuesday, September 25, 2001 5:40 PM To: Si-List Subject: [SI-LIST] JTAG Guru's I am hoping there are a few people in the group that know JTAG fairly well. I am currently using it now for flashing in a new design, but I have some unanswered questions. The JTAG interface is made up of 5 signals: TMS : Test Mode Select TCK : Test Clock TREST_N : Test Reset TDI : Test Data IN TDO : Test Data OUT These signals go into the TAP (Test Access Port) and allow me to do boundary scan and somehow give the part test instructions. Questions: 1. What happens if I continuously toggle the JTAG pins when I am not flashing the part (eg, when it is in 'normal' operation). Will this cause the processor to freak out? Will it matter for some pins but not others? 2. I am unsure what the TMS pin does. Do I need to continuously do something to this pin..or, do I just hold it low for testing? I've read the the TAP controller responds to "changing" of the TMS and TCK. 3. After power-up, before I do testing or flashing, do I need to hold the TRESET_N pin low. 4. Anyone have a short tutorial for JTAG? Thanks for your help, -Trey __________________________________________________ Do You Yahoo!? Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger. http://im.yahoo.com ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu