topic Re: Set JTAG TAP (MCIMX6D) in i.MX Processors

Set JTAG TAP (MCIMX6D)

CameraDeveloper — Tue, 19 Sep 2023 18:42:53 GMT

Hello,

We have a custom board with a MCIMX6D7CZK08AD. We are trying to connect JTAG using a Segger J-Link PLUS Compact and Segger 10-Pin Needle Adapter, to the 10pin TAG CONNECT pattern on our PCB. We have checked the pins and everything seems to be connected correctly.

We are experiencing the following error when trying to connect with JTAG (extended log attached):

TD764 009:716.779 TotalIRLen = 5, IRPrint = 0x01
TD764 009:717.421 JTAG chain detection found 1 devices:
TD764 009:717.573 #0 Id: 0x2191E01D, IRLen: 05, Unknown device
TD764 009:717.640
***** Error:
TD764 009:717.647 CPU-TAP not found in JTAG chain
TD764 009:717.656 - 222.715ms returns 0xFFFFFEFB
TD694 524:514.144 JLINK_GetHWInfo(...)
TD694 524:514.560 - 0.380ms returns 0
TD5B0 525:015.104 JLINK_GetHWInfo(...)

TD5B0 525:015.392 - 0.295ms returns 0

Segger support is saying: "The chip is in some kind of special mode (boundary scan, ...) where not the DAP-TAP (IRLen = 4) is visible on the JTAG chain but another TAP (IRLen = 5)"

(Segger forum link here: https://forum.segger.com/index.php/Thread/9223-Cannot-connect-to-target-CPU-TAP-not-found-in-JTAG-chain/)

How do we adjust the TAP?

Re: Set JTAG TAP (MCIMX6D)

Bio_TICFSL — Wed, 20 Sep 2023 14:45:06 GMT

Hello,

Is probably that the quality of signal is weak, because you are receiving an ID / IRLen unknown device. Here is an application note on data scan boundaries is for mxRT but can apply to iMX6.

https://www.nxp.com/docs/en/application-note/AN12919.pdf

Regards

Re: Set JTAG TAP (MCIMX6D)

CameraDeveloper — Wed, 20 Sep 2023 18:35:29 GMT

The signal flow is out of the IMX6D chip, down the DF40 mezzanine stack, then out to the tag connect pins.

We don't know what would make the signal weak. See wiring diagram between IMX6 and JTAG attached for reference.

Re: Set JTAG TAP (MCIMX6D)

Bio_TICFSL — Thu, 21 Sep 2023 14:47:50 GMT

Hello,

The schematic look ok, but i mean physically anyway o guess you have to do a boundary scan.

regards

Re: Set JTAG TAP (MCIMX6D)

CameraDeveloper — Mon, 25 Sep 2023 05:53:53 GMT

Problem was resolved.

We needed to connect JTAG_MOD to ground, and disconnect the reset (pin10) on J-Link jtag.