http://www.opencircuits.com/api.php?action=feedcontributions&user=76.197.0.39&feedformat=atomOpenCircuits - User contributions [en]2024-03-28T13:31:42ZUser contributionsMediaWiki 1.34.2http://www.opencircuits.com/index.php?title=JTAG&diff=21898JTAG2011-11-01T19:47:49Z<p>76.197.0.39: signals, not pins -the connectors have many more pins</p>
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<div>The Joint Test Action Group (JTAG) standardized a 5 signal boundary-scan test port as IEEE Std. 1149.1, "Standard Test Access Port and Boundary-Scan Architecture".<br />
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While originally intended for boundary-scan testing of PCB assemblies, to replace bed-of-nails testing, the JTAG port included in many popular microprocessors is also often used for programming and debugging.<br />
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[http://hogyros.de/?q=node/167 "If you have information on how to connect a JTAG probe to a Nokia phone, please let me know."]<br />
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There are five signals:<br />
* TCK/clock<br />
* TMS/mode select<br />
* TDI/data in<br />
* TDO/data out<br />
* TRST/reset (optional), when driven low, resets the internal state machine. <br />
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Except for TCK, all other JTAG lines should be pulled high via a resistor.<br />
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WARNING: unconfirmed pinout. Please add links to pinout standard.<br />
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== 20 Pin JTAG PinOut ==<br />
<br />
1 +3.3 V 2 +3.3 V<br />
3 nTRST 4 GND<br />
5 TDI 6 GND<br />
7 TMS 8 GND<br />
9 TCK 10 GND<br />
11 -- 12 GND<br />
13 TDO 14 GND<br />
15 nRST 16 GND<br />
17 -- 18 GND<br />
19 -- 20 GND<br />
<br />
== external links ==<br />
<br />
* [http://openjtag.net/ the OpenJTAG wiki] ( http://openjtag.net/ )<br />
* [http://www.arm.com/support/faqdev/1336.html "When designing development boards what style JTAG connector should I use?"] The 20-pin JTAG connector.<br />
* [http://www.embedded.com/story/OEG20021028S0049 "Introduction to JTAG"] by Rob Oshana 2002<br />
* [http://hri.sourceforge.net/tools/jtag_faq_org.html "JTAG FAQ"] by Stas Khirman 2004 includes a section on [http://hri.sourceforge.net/tools/jtag_faq_org.html#_Toc63218715 14 pin, 20 pin, and 8 pin JTAG headers]<br />
* [http://k9spud.com/jtag/ a parallel port JTAG Debugger circuit for Philips LPC2xxx ARM microcontrollers.] by K9JTAG (uses Schmitt trigger inverters, so it can connect 3.0 V target boards to a standard 5.0 V parallel port)<br />
* [http://diygadget.com/store/building-simple-jtag-cable/info_12.html parallel port JTAG "Building Simple JTAG Cable"] (resistors only)<br />
* [http://www.interfacebus.com/Design_Connector_JTAG_Bus.html "JTAG Bus Description"]<br />
* [http://en.wikipedia.org/wiki/JTAG Wikipedia:JTAG]<br />
* [http://wiki.openwrt.org/OpenWrtDocs/Customizing/Hardware/JTAG_Cable OpenWRT wiki: JTAG Cables]<br />
* [http://jtag-arm9.sourceforge.net/ the Jtag-Arm9 project at Sourceforge] gives instructions and photographs of a [http://jtag-arm9.sourceforge.net/hardware.html Home made JTAG interface] (also shows an example of prototyping using SMT IC)<br />
* [http://freelabs.com/~whitis/electronics/jtag/ the JTAG protocol] by Mark Whitis<br />
* [http://scienceprog.com/avrjtag-clone-in-action/ "Building AVR Jtag clone"] includes schematics and firmware.<br />
* [http://www.embecosm.com/ Embecosm] publishes a "SystemC JTAG interface specification" to simplify debugging complex chips.<br />
* lists a variety of [http://www.freelabs.com/~whitis/electronics/jtag/ JTAG Pinouts]<br />
* [http://tree.celinuxforum.org/CelfPubWiki/ELC2009Presentations?action=AttachFile&do=get&target=DebuggingWithJtagCelf2009.pdf Debugging with JTAG (CELF presentation)]<br />
* Open JTAG Project [http://www.openjtag.org Make your proper high speed JTAG]<br />
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