have a program that utilizes RTC wake up with square wave to gpio pin 4 …all works perfectly when connected to Arduino os but when I switch to battery power …large capacity lithium connected to back of Xiao it refuses to wake up…does not work with 5v through usb port either…seems to only work with serial port on … is this a known issue …has anyone gotten deep sleep to work with a battery and wake up on a pin? Thanx…
Hi there,
You should have a look at the Grove expansion base Xiao ESP32c3 SLEEP, Demo posted on here.
Or Post your code and all the smart folks here will comment.
Yes it does work.
HTH
GL 
PJ