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?

Re: MCXN527 USB ISP

BuS — Wed, 27 May 2026 07:44:27 GMT

Hi,

this is the first prototype of the custom PCB. So this has not worked before.

I use the on chip DCDC_CORE to power LDO_CORE as shown in chapter 35 in the reference manual. I read 1.08V on LDO_CORE.

I also ordered new controllers and the problem is still the same.

Can you please confirm my assumption that this controller should be seen as HID when connected to USB? Is there any kind of driver that must be installed before pluging in?

Thanks!

Steve