JTAG for PCB Panels - Page 1
Forum section: electronics / projects

author: obnauticus
author_rank: Newbie
timestamp: September 14, 2015, 11:53:08 pm
content: Hey,I am wondering if anyone here has any tips on programming multiple (identical) boards in a panel. There was an episode of EEVBlog where Dave mentioned something about breaking out programming headers into one common card-edge connector; however, I am not sure if there are any special nuances that I need to pay attention to while doing this. The boards that I am programming use JTAG.Additionally, how would the JTAG chain look in an entire panel and how would one specify to program multiple devices in one JTAG chain for the programmer? I assume that all the devices will be connected in series (i.e., TDO connected to the next neighbors TDI,, and clock sharing).Thanks!obnauticus

author: cat87
author_rank: Regular Contributor
timestamp: September 15, 2015, 05:43:26 am
content: In production, I haven't had boards which are programmed more at once, so can't really help you here, but I have done a lot of boards that have multiple IC's on them, all programmed through JTAG. As you said, the TDO from one is daisy chained with the TDI from another. It might be the same thing, but I can not be sure.How this thing works is you must make a JTAG sequence in a program such as the JTAG ProVision (this is actually crap; hard to use and not user friendly, plus I don't know if it's free) or the AEX Sequencer (this is somewhat easyer to play with) In the sequence, you specify what kind of IC or ICs you are programming, then the path to the SW the JTAG program should load onto the IC, then maybe a few boundary check tests, (if needed, for high density pin ICs or BGAs) to check for any unsoldered or shorted pins.These kinds of things are somewhat touchy so expect a lot of fiddling around, both with the hardware part and the software part (setting the right clocks, the right sequence order, etc.)Hope this info is somewhat helpful to you.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 15, 2015, 06:20:01 am
content: I just used 5 programmers and a overlay application calling 5x the OEM's programmer command line software.Cheap & Fast (developed), but still at least 5x improvement in manual programming work.Quantity: 100's per job.

author: daqq
author_rank: Super Contributor
timestamp: September 15, 2015, 06:23:56 am
content: I wondered about this as well, but decided against it - the moment any board of the panel is faulty none of the boards are accessible. Especially if there's some nasty problem like +12V shorted onto TCKWouldn't a JTAG header on the board be better? Or take the signals of each of the boards and output them in one place?

author: obnauticus
author_rank: Newbie
timestamp: September 16, 2015, 10:47:39 pm
content: Great ideas so far. I didn't consider the single point of failure scenario in the panel so thanks for saving me there.Can any of you guys recommend a good JTAG programmer? Ideally we'd get one of those industrial JTAG programmers that can test/program multiple devices (I think XJTAG sells one). That being said, if you know of one good jtag programmer we could just buy a handfull of those to program the panels instead.Thomas.