Difference between revisions of "JTAG"

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(yet more pinouts)
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* [http://www.arm.com/support/faqdev/1336.html "When designing development boards what style JTAG connector should I use?"] The 20-pin JTAG connector.
 
* [http://www.arm.com/support/faqdev/1336.html "When designing development boards what style JTAG connector should I use?"] The 20-pin JTAG connector.
 
* [http://www.embedded.com/story/OEG20021028S0049 "Introduction to JTAG"] by Rob Oshana 2002
 
* [http://www.embedded.com/story/OEG20021028S0049 "Introduction to JTAG"] by Rob Oshana 2002
* [http://hri.sourceforge.net/tools/jtag_faq_org.html "JTAG FAQ"] by Stas Khirman 2004
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* [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]
 
* [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)
 
* [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)
 
* [http://diygadget.com/store/building-simple-jtag-cable/info_12.html parallel port JTAG "Building Simple JTAG Cable"] (resistors only)
 
* [http://diygadget.com/store/building-simple-jtag-cable/info_12.html parallel port JTAG "Building Simple JTAG Cable"] (resistors only)
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* [http://scienceprog.com/avrjtag-clone-in-action/ "Building AVR Jtag clone"] includes schematics and firmware.
 
* [http://scienceprog.com/avrjtag-clone-in-action/ "Building AVR Jtag clone"] includes schematics and firmware.
 
* [http://www.embecosm.com/ Embecosm] publishes a "SystemC JTAG interface specification" to simplify debugging complex chips.
 
* [http://www.embecosm.com/ Embecosm] publishes a "SystemC JTAG interface specification" to simplify debugging complex chips.
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* lists a variety of [http://www.freelabs.com/~whitis/electronics/jtag/ JTAG Pinouts]
  
 
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Revision as of 21:17, 6 May 2009

The Joint Test Action Group (JTAG) standardized a 5 pin boundary-scan test port as IEEE Std. 1149.1, "Standard Test Access Port and Boundary-Scan Architecture".

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.

"If you have information on how to connect a JTAG probe to a Nokia phone, please let me know."

There are five pins:

  • TCK/clock
  • TMS/mode select
  • TDI/data in
  • TDO/data out
  • TRST/reset (optional), when driven low, resets the internal state machine.

Except for TCK, all other JTAG lines should be pulled high via a resistor.


WARNING: unconfirmed pinout. Please add links to pinout standard.

20 Pin JTAG PinOut

    1 +3.3 V    2 +3.3 V
    3 nTRST     4 GND
    5 TDI       6 GND
    7 TMS       8 GND
    9 TCK      10 GND
   11  --      12 GND
   13 TDO      14 GND
   15 nRST     16 GND
   17  --      18 GND
   19  --      20 GND

external links