Hi,
When I am trying to detect my target platform for i.MX8Mplus processor using the ARM Development Studio v2025.0-1 . I am getting prints like this
[23/09/25 12:02:59] Arm Development Studio v2025.0-1, build number 2025010903
[23/09/25 12:02:59] JTAG Clock Speed : 7500000Hz
[23/09/25 12:02:59] Beginning Autodetection
[23/09/25 12:03:00] --- --- ---
[23/09/25 12:03:00] Connected to Debug Probe
[23/09/25 12:03:00] Counting devices:
[23/09/25 12:03:00] DR Chain [136]:
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000
[23/09/25 12:03:00] Device Count: 136
[23/09/25 12:03:00] Detected number of devices = 136, maximum allowed = 128. This problem is usually a result of the scanchain not acting correctly when using JTAG scans to count the number of devices.
[23/09/25 12:03:00] Performing legacy SWD->JTAG switch
[23/09/25 12:03:00] Performing Dormant Mode SWD->JTAG switch
[23/09/25 12:03:00] Disconnected from Debug Probe
[23/09/25 12:03:05] JTAG detection failed, trying SWD
[23/09/25 12:03:05] WARNING - Multi-drop SWD is not supported, a single DAP on the scanchain has been assumed.
[23/09/25 12:03:05] The scanchain must be built manually if more scanchain devices are present.
[23/09/25 12:03:07] --- --- ---
[23/09/25 12:03:07] Disconnected from Debug Probe
[23/09/25 12:03:07] Unable to connect to device ARMCS-DP
We are using DSTREAM-ST for 8MPLUSLPD4-EVK board.
In debug configuration we are able to detect DSTREAM-ST and selected I.MX8MPLUS EVK in baremetal selected cortex M7. We tried by changing different frequencies but getting the same error as shown in the below snippet. We followed the procedure you have mentioned.
In debugging tab we enabled Connect only after that clicked on debug. We are getting failed to connect to any devices on the target. Check that the target is correctly connected to the debug probe and powered on.
The board is working because it is booting from EMMC Flash. can you guide us to debug through JTAG for the 8MPLUSLPD4-EVK.
Thanks & Regards,
K.Bhardwaj
Hi again
I'm not very familiar with the i.MX8Mplus, but the board documentation "Getting Started with MCUXpresso SDK for EVK-MIMX8MP.pdf" says:
>For the security reason, only after the U-Boot is boot up, the JTAG can be allowed to connect to M core.
Is your board booting into Linux? If not, I think you'll need to (at least start the) boot into Linux:1) Prepare a microSD card with a Linux image2) Connect a serial terminal emulator such as PuTTY to the COM port (as shown in the guide above)3) Power up the board and hit a key on the U-Boot startAlso, check pin JTAG_MOD. Some users on the NXP Community have reported related issues there. See e.g.
https://community.nxp.com/t5/i-MX-Processors/I-MX8M-Plus-Enter-JTAG-Debug/m-p/1577793
and
https://community.nxp.com/t5/i-MX-Processors/iMX8M-Plus-Cortex-M7-JTAG-Debug-quot-Could-not-measure-IR-len/td-p/1660528
Hope this helps
Stephen
Hi Stephen,
We connected the USB-UART port in I.MX8MPLUS to PC(Windows) and connected to putty. In U-Boot we stopped the booting then we did debug in arm development studio using DStream-ST jtag. Still we are getting the same error.
Hi againSorry, I meant to add:After interrupting u-boot, issue this command:u-boot=> bootaux 0x7e0000## Starting auxiliary core stack = 0xEDFE0DD0, pc = 0x28040000...In our tests (with an early board/distro) we also needed to issue this command, but sorry, I don't know whether it will be needed for your setup, or whether the values might need to be different:u-boot=> md.w 0x30340058 0xFFFFFFFEFor more information see section 4.7.4.1.2 ofwww.nxp.com/.../UG10163.pdfIf you still need more help, I suggest you reach out to the NXP Community athttps://community.nxp.com/who are best placed to advise on the specifics of their board boot, or "Open a Support Case" with Arm using the Support link at the bottom of this page.Stephen