MCX MicrocontrollersのトピックRe: MCXN527 USB ISP

MCXN527 USB ISP

BuS — Fri, 15 May 2026 14:34:31 GMT

Hello,

i am new to the MCX Controllers, and i can not establish an USB connection.

I use a MCXN527VKLT Controller, and I have connected:

-USB0-DM and -DP

-VDD_USB (over a 3.3V regulator)

-VSS_USB

-USB0_VBUS_DET to 5V from USB

My expectations are that when I pull ISPMODE_N pin to GND via a switch, then plug in USB in my computer, open the ISPMODE_N switch, the controller should be seen as an HID?

I also tried testing the connection with the secure provisioning tool.

What am I missing?

Thanks in advance and sorry for this beginner question.

Steve

Re: MCXN527 USB ISP

carlos_o — Fri, 15 May 2026 19:56:16 GMT

Hi @BuS

Thank you for your post,

Could you confirm your external crystal oscillator value?

The UG10092: MCX N Series Hardware Design Guide | NXP Semiconductors has a note that is relevant in the case of ISP over USB: If using the HS USB in In-system programming (ISP) mode, a 24 MHz crystal must be used in at least the first access of the device. However, the user can modify the security fuse configuration to allow a different crystal. However, the user must configure it. For example, factory configuration requires a 24 MHz crystal for HS USB ISP operation.

Re: MCXN527 USB ISP

BuS — Sat, 16 May 2026 11:03:25 GMT

Hi,

there is a 24MHz crystal attached to pin P1_30 and P1_31.

Steve

Re: MCXN527 USB ISP

carlos_o — Mon, 18 May 2026 20:53:51 GMT

Hi @BuS

thank you for clarifying!

Please review the VDD_CORE voltage.

USB HS is not supported when VDD_CORE < 1.1 V

Also review that your system follows the 2.5 Required Power-On-Reset (POR) Sequencing described at Highly integrated low-power dual-core Arm Cortex M33 MCU with on-chip accelerators

Could you confirm if you were able to use your custom board before?