KW45: Intermittent Wire ACK Fault During Programming/Debugging and Flash Erase Failure

[Prashanth1]

Hi Team,

I am currently working with a KW45-based custom board and facing an intermittent issue during programming and debugging the firmware.

I have tested the board with both a SEGGER J-Link and an NXP MCU-Link debug probe, and the issue occurs with both probes.

The custom board has the same boot configuration as the KW45 EVK, and the JTAG/SWD connections have also been checked and appear to be correct.

However, I am seeing the following behaviour:

When I try to dump or program a known-working application:

• Sometimes the application is programmed successfully, but after programming or starting a debug session, the device eventually jumps to a fault address.
• The debugger then halts at that location.
• During some programming or dumping attempts, I receive a Wire ACK fault.
• At other times, MCUXpresso reports:
  Error while executing the MI command
• I also tried to erase the flash from MCUXpresso, but the flash erase operation itself does not complete successfully.

Checks already performed

• JTAG/SWD connections have been checked and appear to be correct.
• The issue was tested with both a SEGGER J-Link and an NXP MCU-Link debug probe.
  Boot configuration has been compared with the KW45 EVK.
• I am using a known-working application for testing.
  The issue is intermittent: programming sometimes succeeds, but at other times a Wire ACK fault or MI command error occurs.
• Flash erase has also been attempted, but it does not complete successfully.

My questions

• What could cause the KW45 to: Intermittently report a Wire ACK fault while dumping or programming code?
• Report Error while executing the MI command?
• Jump or halt at an unexpected or invalid memory address after programming?
• Fail even when attempting a full flash erase?

Since the issue includes intermittent Wire ACK faults and failure during flash erase, I suspect this may be related to the debug interface, SWD/JTAG signal integrity, power-supply stability, reset sequence, flash controller state, device security/configuration, boot configuration, or another hardware-level issue rather than the application itself.

1. Could you please suggest the recommended procedure to:
2. Recover or erase the KW45 device.
3. Verify that the debug interface is functioning correctly.
4. Check whether the device is secured or in a state that prevents normal programming.
5. Determine whether the Wire ACK fault is caused by the target hardware, debug probe, power/reset behavior, or SWD/JTAG signal integrity.

I can provide the following information if required:

• MCUXpresso IDE version: 25.6.1
• Debug probes tested: SEGGER J-Link and NXP MCU-Link
• Complete error log, including the Wire ACK fault details
• Debug console output
• Schematic of the JTAG/SWD and boot connections
• SWD/JTAG clock frequency
• Power-supply and reset configuration
• Memory/register information from the failed state

Any guidance on the recommended troubleshooting steps would be greatly appreciated.

Thanks in advance.