Hi NXP,
We refer NXP SDK_2_14_0_FRDM-MCXN236_rfp USB device example to develop a USB device. However, is it possible to make the USB device mode work without VBUS?
If yes, how can we modify this in the SDK?
Thanks,
Alan
Hi @allu
Thank you very much for your patience.
As I reviewed internally, please find below our feedback.
We strongly suggest customers to link MCX N2xx's USB_VBUS pin with USB connector as recommended in our hardware design guide and implemented in the official FRDM-MCX N 236 schematic.
With the USB_VBUS pin detect, the application firmware can easily know if the USB is attached or not.
Leaving USB_VBUS floating is possible, but require the software skip the attach detection, and use a software state machine to check if the USB is linked or not. But we are not sure about the workload to implement this.
Additonally, leaving USB_VBUS disconnect may impact on the USB certification attach and de-attach test, but it will not impact on other test items. As mentioned before, you may use the software approach to solve the attach and de-attach test item issue, but it is not our recommendation.
Anyway, we strongly suggest you to enable the USB_VBUS.
Thank you,
Diego