Author: TakashiM_61 Version: **
Translation - Japanese: USB WKUPによるUSB動作クロック停止モードからのF2MC-16LXウェイクアップの問題 - KBA227510 - Community Translated (JA)
Question: How can I resolve the issue of the F2MC-16LX family not waking up from USB operation clock stop mode using USB WKUP as an interrupt trigger?
Answer: The F2MC-16LX family cannot wake up from USB operation clock stop mode using USB WKUP as an interrupt trigger. This is because the clock in USB operation part “UDC” (see the following block diagram) is gated during the USB operation clock stop mode.
However, if USB WKUP detection is required in the USB operation clock stop mode, SUSP in UDCS register must be “1”, which means that the USB function is in Suspend Detection mode.
To shift a USB device from suspend status to wake-up status, the USB protocol provides the following two methods:
- Remote wake-up from the USB device
- Wake-up from USB host
If remote wake-up from the USB device is adopted, SUSP in UDCS register can be 0. Since the USB Bus can be ignored, USB WKUP is not a trigger to wake up from STOP mode. The device should be recovered through external interrupt.
If wake-up from USB host is adopted, USB WKUP is expected. That means SUSP in UDCS register must be 1.
Only the MB90335 and MB90330A series have the USB function in the F2MC-16LX family.