topic Re: MCXN947 USB hardware design in MCX Microcontrollers

MCXN947 USB hardware design

ashwinanil — Fri, 23 Jan 2026 18:25:10 GMT

I would like to configure USB 2.0 HS (USB1) as Peripheral only on the MCXN947VDFT.

I do not need OTG functionality and do not want to add the VBUS Power Control or CC Logic ICs as demonstrated on the FRDM-MCXN947 dev board if not needed.

I’m using USB type C connector
CC1 and CC2 pins are pulled down using 5.1k resistors
Can the ID pin remain floating on the uC side?

Do I need the resistor divider for the USB1_VBUS pin. The MCX-N9XX-EVK adds the divider. The FRDM-MCXN947 does not. Pin is stated to be 5V tolerant.

Will this design work? Any insight is appreciated. Thank you

Re: MCXN947 USB hardware design

carlos_o — Fri, 23 Jan 2026 22:37:06 GMT

Hi @ashwinanil

Thanks for your post

Please refer to the UG10092: MCXNx4x Hardware Design Guide | NXP Semiconductors, there you focus on the chapter 8.3 High-speed USB (that also refers to chapter 8.1) and 11 Unused pins.

The VBUS recommendation is to connect it directly to the USB connector, without using a resistor divider. As noted in the documentation: "The USB VBUS pin is a unique pin in that it is the only 5 V tolerant pin. The VBUS pin from the connector must be routed directly to the USB_VBUS MCX pin."

The USB_ID the recommendation is leave unconnected

Let me know if this information helps.

Re: MCXN947 USB hardware design

ashwinanil — Mon, 26 Jan 2026 16:47:28 GMT

Hi @carlos_o

Thank you for the response. I followed your guidance and connected the 5V pin directly to the usb_vbus MCXN pin without the voltage divider. The rest of the pins are configured as attached above and I am not using the CC logic chip that controls OTG, not sure if its required. Regardless, I am still not able to get USB to work. I suspect it's a firmware issue at this point.

Thanks for the help!

Re: MCXN947 USB hardware design

carlos_o — Tue, 27 Jan 2026 20:42:19 GMT

Hi @ashwinanil

How are you testing the USB functionality?

Re: MCXN947 USB hardware design

wima88 — Tue, 27 Jan 2026 21:07:04 GMT

Hi @carlos_o
we are using zephyr testusb sample in Linux for testing. when using the evk we can see the device enumeration and, we can run the usb tests. but when we try to use the custom bord we are getting enumeration error see below dmesg log from the host side.

[1115238.671144] usb 1-2: new high-speed USB device number 36 using xhci_hcd

[1115238.785192] usb 1-2: device descriptor read/64, error -71

[1115239.003075] usb 1-2: device descriptor read/64, error -71

[1115239.219143] usb 1-2: new high-speed USB device number 37 using xhci_hcd

[1115239.333176] usb 1-2: device descriptor read/64, error -71

[1115239.555205] usb 1-2: device descriptor read/64, error -71

[1115239.657153] usb usb1-port2: attempt power cycle

[1115240.037109] usb 1-2: new high-speed USB device number 38 using xhci_hcd

[1115240.037252] usb 1-2: Device not responding to setup address.

[1115240.241247] usb 1-2: Device not responding to setup address.

[1115240.449124] usb 1-2: device not accepting address 38, error -71

[1115240.562935] usb 1-2: new high-speed USB device number 39 using xhci_hcd

[1115240.563074] usb 1-2: Device not responding to setup address.

[1115240.769196] usb 1-2: Device not responding to setup address.

[1115240.977079] usb 1-2: device not accepting address 39, error -71

[1115240.977312] usb usb1-port2: unable to enumerate USB device

Indicating that device in this case custom board is not responding to setup packet from Host

Re: MCXN947 USB hardware design

carlos_o — Tue, 03 Feb 2026 18:58:05 GMT

Hi @wima88

Apologies the late reply

Since you are using Zephyr with a custom board, please refer to the following Zephyr custom boards and applications

There are some tips you could follow when developing code to a custom board using Zephyr.

Re: MCXN947 USB hardware design

wima88 — Tue, 31 Mar 2026 13:58:13 GMT

This was resolve , thanks for the support @carlos_o . issue was mismatched clock frequency on HW /FW setup