Board Bringup - No JTAG Response - What are the most basic requirements for JTAG response?

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Board Bringup - No JTAG Response - What are the most basic requirements for JTAG response?

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jeffkrupp
Contributor II

Using a custom board very similar to the Sabre Lite using an IMX6 quad core, the board is not booting.  Taking a step back, JTAG does not have a response (see output below) and can not ID the chip.  Power supplies were confirmed to be sequenced properly, are at the proper DC level, and are clean DC for both input supplies and generated supplies VDDARM23_CAP, VDDARM_CAP, and VDDPU_CAP.  Reset circuit signals are also correct, toggling ON 600ms after the supplies are stable.  If the power supplies are ok and the jtag connections are ok, is there anything else that could prevent JTAG from working?

I've confirmed also that the jtag tool and cabling works ok by using it on a Sabre Lite board.

Thank you for any suggestions you can offer.

JTAG circuit:

jtag.png

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JTAG Output:

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SEGGER J-Link Commander V4.98e ('?' for help)

Compiled May  5 2015 11:01:31

DLL version V4.98e, compiled May  5 2015 11:00:52

Firmware: J-Link ARM / Flasher ARM V4 compiled Mar 31 2015 22:22:18

Hardware: V4.00

S/N: 164102666

Feature(s): JFlash, GDB

IP-Addr.: 255.255.255.255 (DHCP)

VTarget = 3.282V

Info: Could not measure total IR len. TDO is constant high.

Info: Could not measure total IR len. TDO is constant high.

No devices found on JTAG chain. Trying to find device on SWD.

No device found on SWD.

Failed to identify target. Trying again with slow (4 kHz) speed.

Info: Could not measure total IR len. TDO is constant high.

Info: Could not measure total IR len. TDO is constant high.

No devices found on JTAG chain. Trying to find device on SWD.

No device found on SWD.

No device found at all. Selecting JTAG as default target interface.

J-Link>

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Jeff

one can check that JTAG_MODE=0, NVCC_JTAG is applied.

For bsld operation one needs to have PCIE_VP, PCIE_VPH, PCIE_VPTX

powered (from Table 2-21. Recommended connections for unused analog interfaces IMX6DQ6SDLHDG)

One can also check sect.2.6 JTAG signal termination, Chapter 7 Configuring JTAG Tools,http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf?fasp=1&WT_TYPE=Users%20Guide...

check that 24MHz and 32.768KHz clocks are running.

Blowing fuse SJC_DISABLE disabes jtag (from Table 5-10. Fusemap Descriptions IMX6DQRM)

Best regards

igor

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Jeff

one can check that JTAG_MODE=0, NVCC_JTAG is applied.

For bsld operation one needs to have PCIE_VP, PCIE_VPH, PCIE_VPTX

powered (from Table 2-21. Recommended connections for unused analog interfaces IMX6DQ6SDLHDG)

One can also check sect.2.6 JTAG signal termination, Chapter 7 Configuring JTAG Tools,http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf?fasp=1&WT_TYPE=Users%20Guide...

check that 24MHz and 32.768KHz clocks are running.

Blowing fuse SJC_DISABLE disabes jtag (from Table 5-10. Fusemap Descriptions IMX6DQRM)

Best regards

igor

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

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jeffkrupp
Contributor II

It was the clock source!  I changed it to a 16MHz and I am now able to JTAG ID the chip!  It is possible the 24MHz crystal was damaged.  I'll experiment further by changing to a new 24MHz source and step through the boot process.  It is great to see it finally has a pulse.  Thanks!

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jeffkrupp
Contributor II

Thank you for your thoughts.  Here's what I checked:

JTAG_MODE is 0,

NVCC_JTAG is 3.3V,

PCIE_VP=VDDSOC_CAP(1.112V),

PCIE_VPH=2.5V 

VCIE_VPTX=VDDSOC_CAP (filtered 1.112V)

JTAG terminations are outputs of a buffer IC that has pull-up\pull-downs as inputs, except TMS and TCK floating input to buffer, and TDO is a floating input to the buffer (no pullup\pulldown) per docs, so it all seems to comply.

The clock sources do not seem to be running.  I will try to get them running (perhaps it is a load capacitance problem), but I assumed the chip could run via jtag without the clock sources - do you know?

The IMX6 IC is new from a reputable distributor (Digikey), so the fuses should be default.  I can't confirm without JTAG working.

Thanks for your help.  If you know about whether clock sources are needed for JTAG, that would help further.  Also open to other ideas. 

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sinanakman
Senior Contributor III

Hi Jeff

I noticed one more thing. Can you put pull-ups on TMS

and TCK pins. (pin #2 and #4). Also I see that your RESET_N

is pulled high (pin 10). Can you remove that pull-up and

scope this as well.

Hope this helps.

Sinan Akman

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jeffkrupp
Contributor II

I scoped TDO before the buffer and confirmed as the JTAG output is reporting - it stays constant high.  Next, I added pull-ups to TMS and TCK, removed the reset pull-up and confirmed the same JTAG response.  I see that RESET_N toggles, as controlled by the JTAG software\hardware, but TDO stays high.

Thanks for your help, but it is still unable to jtag ID the chip.  If you have any other suggestions or ideas, I'm open to trying them\checking. 

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sinanakman
Senior Contributor III

Hi Jeff

If power supplies are correct and despite TMS. TCK

activity if you see no signal on TDO, what comes to

my mind is that perhaps your SoC has enabled secure

boot with no JTAG. Are any fuses blown on this SoC ?

Sinan Akamn

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sanjeevsharma
Contributor IV

Hello Sinan Akman,

I have come across your post and looks like you have good understanding of BDI3000 on imx6 platform.Do you have some steps to load u-boot to SRAM on sabrelite base custom board using BDI3000 debugger.

Regards

Sanjeev Sharma

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sinanakman
Senior Contributor III

Hi Sanjeev

What you need is essentially a config file for BDI3000 that

initializes the SRAM and a version of u-boot that does not

do those initialization. You can then RESET HALT via

your BDI3000 then load the u-boot image to memory and

run it from there.

I suggest that you start a new thread for your question as it

is now different than the original question for this thread.

We can then all follow up on the new thread. Please note

that I am traveling during the next few weeks so my response

might be delayed sometimes.

Regards

Sinan Akman

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jeffkrupp
Contributor II

Well, I have (3) prototypes, all built with new chips from Digikey.  I don't have any way of knowing about the fuse status, but it should be running defaults.  Thanks for your ideas.

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sinanakman
Senior Contributor III

Hi Jeff

Can you scope JTAG_TDO before it goes into

the buffer ?

Regards

Sinan Akman