I'm on JLink V632b, target iMX7D, on M4 core.

On some cases when trying to connect with JLink the device gets totally hardlocked, seems followed by SoC reset, with halt of main core, and total deadlock / not able to connect to target anymore with JLink.

I see this trace:
J-Link: Bad JTAG communication: Write to IR: Expected 0x1, got 0xF (TAP Command : 10) @ Off 0x5.
Could not find core in Coresight setup

After this I have to full reset the board. Any help on this ?


JLink trace log :

J-Link: Device "MCIMX7D7_M4" selected.
J-Link: *************************************************
J-Link: J-Link script: iMX7D Cortex-M4 core J-Link script
J-Link: *************************************************
J-Link: TotalIRLen = 4, IRPrint = 0x01
J-Link: JTAG chain detection found 1 devices:
J-Link: #0 Id: 0x5BA00477, IRLen: 04, CoreSight JTAG-DP
J-Link: AP map detection skipped. Manually configured AP map found.
J-Link: AP[0]: AHB-AP (IDR: Not set)
J-Link: AP[1]: APB-AP (IDR: Not set)
J-Link: AP[2]: CUSTOM-AP (IDR: Not set)
J-Link: AP[3]: CUSTOM-AP (IDR: Not set)
J-Link: AP[4]: AHB-AP (IDR: Not set)
J-Link: AP[4]: Skipped. Could not read AHB ROM register
J-Link: AP map detection skipped. Manually configured AP map found.
J-Link: AP[0]: AHB-AP (IDR: Not set)
J-Link: AP[1]: APB-AP (IDR: Not set)
J-Link: AP[2]: CUSTOM-AP (IDR: Not set)
J-Link: AP[3]: CUSTOM-AP (IDR: Not set)
J-Link: AP[4]: AHB-AP (IDR: Not set)
J-Link: AP[4]: Skipped. No ROM table (AHB-AP ROM base: 0x00000000)
J-Link: *************************************************
J-Link: J-Link script: iMX7D Cortex-M4 core J-Link script
J-Link: *************************************************
J-Link: *************************************************
J-Link: J-Link script: iMX7D Cortex-M4 core J-Link script
J-Link: *************************************************
J-Link: Bad JTAG communication: Write to IR: Expected 0x1, got 0xF (TAP Command : 10) @ Off 0x5.
Could not find core in Coresight setup
J-Link: *************************************************
J-Link: J-Link script: iMX7D Cortex-M4 core J-Link script
J-Link: *************************************************
J-Link: *************************************************
J-Link: J-Link script: iMX7D Cortex-M4 core J-Link script
J-Link: *************************************************
Connection failed

Hi,

Note that I noted that in _some_ cases you get this issue. So I wouldn't expect you to hit every time the problem.

I also noted that , from your screenshot, you don't seem to be using Segger provided JLink connect script ? - NXP_iMX7D_Connect_CortexM4.JLinkScript.
I see you select the device in the command shell.

In my connect I use the script - NXP_iMX7D_Connect_CortexM4.JLinkScript. I don't specify -device as you do, I just put Cortex-M4. ( as the script handles device connection anyway .. ? )

My connect string looks like :

JLinkExe -device Cortex-M4 -autoconnect 1 -if JTAG -speed 4000 -JTAGConf -1,-1 -JLinkScriptFile << path to script >>

And similarly for JLinkGDBServer .

Does it matter here if you use proper MCIMX... M4 device name, or Cortex-M4, if you using the connect script?