topic Re: Unable to debug MCXN546VKLT on my custom board in MCX Microcontrollers

Unable to debug MCXN546VKLT on my custom board

durgesh_ravi — Sat, 14 Mar 2026 07:28:40 GMT

Hello all,

I am new to use NXP microcontrollers and using MCXN546VKLT on my custom board.

I am able to successfully debug my code on evaluation board MCX-N5XX-EVK, which is using MCXN547VDFT.

But the problem is when trying to debug on my custom board, I am getting error as - "Wire ACK Fault in DAP access"

A screenshot is attached to see the log comparison between MCXN547VDFT (successful) and MCXN546VKLT (unsuccessful) flash.

Also, when trying to debug I MCUEXPRESSO IDE, getting below errors:

Please help me with this, waiting for the quickest reply as time is a major issue.

Re: Unable to debug MCXN546VKLT on my custom board

Harry_Zhang — Mon, 16 Mar 2026 10:25:38 GMT

Hi @durgesh_ravi

Based on your picture, “Wire ACK Fault in DAP access” almost always means the probe cannot reliably talk to the ARM Debug Access Port (DAP) over SWD on your custom board.

I think you should first check the hardware wiring of the SWD interface and the nRESET circuit.

You can refer to the mcxn547 evk schematic.

Harry

Re: Unable to debug MCXN546VKLT on my custom board

durgesh_ravi — Tue, 17 Mar 2026 05:10:44 GMT

Hi @Harry_Zhang , Thanks for the quick response.

I have crosschecked end to end connectivity for CLK, GND, RESET, SWO, SWO multiple times also compared with mcxn547 evk schematic.

I am attaching my custom board schematic here for your reference. Please tell us whether we are missing something.

@krishna_mohan

PS: We have also tried ISP using UART (used P1_8 and P1_9 pins) ---