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

Prashanth1 — Tue, 08 Sep 2026 08:07:59 GMT

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.

Could you please suggest the recommended procedure to:
Recover or erase the KW45 device.
Verify that the debug interface is functioning correctly.
Check whether the device is secured or in a state that prevents normal programming.
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.

Wireless MCUのトピックKW45: Intermittent Wire ACK Fault During Programming/Debugging and Flash Erase Failure

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