Some questions about USB development

[H-chips]

Dear Community,

I am using MPC5748G for USB device development. The voltage of my VBUS is about 4.8V, which has exceeded the threshold of 4.4V mentioned in the manual. Why is UOTG_OTGSC[AVV] always 0?

Also, I want to know when the device descriptor should be set? Here's what I think:

The Host and Device communication is through two lines, DM and DP, while these two lines are directly connected to the USB3340, which is connected to the MCU through the ULPI protocol. Therefore, the REQUEST_DESCRIPTOR signal can be considered as a request that is converted into ULPI signal by the DM and DP to the USB3340 and sent to the MCU.

But I can't find a register in the manual where the MCU sets the device descriptor upon receiving REQUEST_DESCRIPTOR, nor a register where the device descriptor is entered and sent in response to the Host request.

Can someone answer this question for me? If there is anything wrong with my ideas, please correct me. Thank you very much for your help.

regards

H-chips

#MPC5748G

[PetrS]

Hi,

due to limited resources, we are currently unable to support such request. If more extensive support is required, please contact field application engineer assigned to you - either NPX FAE and distribution FAE. If don’t have such contact yet, please contact our local distributor:

https://www.nxp.com/support/sample-and-buy/distributor-network:DISTRIBUTORS

An option is to use our paid professional engineering services:

https://www.nxp.com/support/support/nxp-engineering-services:SW-SUPPORT

Thanks for understanding.

BR, Petr

[H-chips]

Ok, thank you very much for your help