[ABANDONED] iMX8M Plus Cortex-M7 JTAG Debug "Could not measure IR len. TDO is constant high"

This site uses cookies. By continuing to browse this site, you are agreeing to our Cookie Policy.

  • [ABANDONED] iMX8M Plus Cortex-M7 JTAG Debug "Could not measure IR len. TDO is constant high"

    Hello,
    I am currently trying to debug the Cortex-M7 coprocessor of the i.MX8MP. However, I cannot establish a connection and get the error message "Could not measure IR len. TDO is contant high".
    I have already measured the physical connection several times. The pins used are: JTAG_RST, JTAG_TDO, JTAG_TCK, JTAG_TMS, JTAG_TDI, JTAG_nTRST, 3V3 and GND.
    I also use the JLinkScript for the i.MX8MP (SDK_MX8MP_3RDPARTY_Patch) in combination with the J-Link Plus debug probe. What confuses me a bit is that in the JLinkScript the ResetTarget() function is empty.
    The reference manual (document number: IMX8MPRM) contains the following sentence "When Arm platform access to the SDMA OnCE is enabled (that is, when the bit in the
    ONCE_ENB register is set), the JTAG access is disabled." When I read the SDMAARMx_ONCE_ENB registers, there is a 0 in each register, which means that the arm platform access should be disabled, yet still I cannot connect via JTAG.
    If I try to connect via SWD I just get "Cannot connect to target."