USB virtual com port can't receive data when device reboot

[hjuns]

Hello,

I experienced a phenomenon in which the USB port was not reconnected.

This phenomenon occurs when a USB port is connected to the product and reboots.

I check my device manager.

When i turn off product, com port also disappear.

and product reboot then com port appear.

But i can't receive any data.

When i reconnect USB cable then communication work well.

Summary

1. USB virtual com port can't receive data when device reboot.
2. In the same state as above, USB cable reconnect then USB connect well.

I need your support.

Thanks. best regards.

[Pavel A.]

After the device restarts, do you see the enumeration process? If not, it's the time to unpack your USB bus analyzer,

[hjuns · Accepted solution]

I solved this problem.

It need USB gpio pull down.

If device restart then USB gpio pull down.

[TDK]

Huh? What is a USB gpio pull down?

[hjuns]

USB_OTG_FS_DM, USB_OTG_FS_DP need pull down.