i.MX JTAG hot plug with no reset

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i.MX JTAG hot plug with no reset

i.MX JTAG hot plug with no reset

When you do long test (days or weeks) test on i.MX board and your test fails, you often wants to know what has happen with a JTAG probe.

The problem is when you have 50 boards running in parallel, you don't have the budget to have 50 JTAG debug probe.

If you do a "hot plug" of your JTAG probe, you have roughly one chance out 2 to reset your board... so you'll have to wait another couple of hour to resee the problem.

Anyway to have a reliable JTAG plug with no reset, it is really simple... cut the RESET line on your cable! then you'll still be able to "attach" to your i.MX.

On the MEK board, with a 10-pin JTAG connector, you have the cut the cable line 10 of the ribbon cable:


On the cable, cut the reset line like this:


With my Lauterbach JTAG  probe, when I do a "hot plug" I never have a reset of my i.MX.




Hi Vincent

May I add to your nice document that with some of the JTAG debuggers

such as BDI3000 and PEEDI, you can configure it so that the debugger

will not control the RESET line so perhaps this might help certain cases.

Although the debugger may still need to reset the TAP controller (not the

board) so I don't know how this would effect.

Best regards

Sinan Akman


I could be interesting you do the test! With rich OS such as Linux or QNX, it is quick and quite easy as you just have to monitor the prompt.

I am also wondering if the GND is not a problem as on the contrary of USB connectors, it can arrive later on JTAG connectors (all the pins have the same length, even GND).



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