Difference between revisions of "JTAG"
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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 | + | * [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. | ||
+ | * 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
- the OpenJTAG wiki ( http://openjtag.net/ )
- "When designing development boards what style JTAG connector should I use?" The 20-pin JTAG connector.
- "Introduction to JTAG" by Rob Oshana 2002
- "JTAG FAQ" by Stas Khirman 2004 includes a section on 14 pin, 20 pin, and 8 pin JTAG headers
- 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)
- parallel port JTAG "Building Simple JTAG Cable" (resistors only)
- "JTAG Bus Description"
- Wikipedia:JTAG
- OpenWRT wiki: JTAG Cables
- the Jtag-Arm9 project at Sourceforge gives instructions and photographs of a Home made JTAG interface (also shows an example of prototyping using SMT IC)
- the JTAG protocol by Mark Whitis
- "Building AVR Jtag clone" includes schematics and firmware.
- Embecosm publishes a "SystemC JTAG interface specification" to simplify debugging complex chips.
- lists a variety of JTAG Pinouts