I am Building a new 2.5 “ using a iFlight SucceX Mini F4 TwinG V3 stack. STM32F405 4.0.4 firmware

Is it normal for a fc to not be able to power a rx on usb(R9mm Rx)

Also, when I use battery there is approx 2 sec delay before fc sees the rx and gives the last arming 2 beeps. I checked my usb and it puts out 5v. The fc 5V rail only shows 2.14v on usb. But when I use battery both 2s and 4s it puts a steady 4.95v out and the rx seems fine.

Some FCs power all the 5V pads when connected via USB, some FCs don't power any of the 5V pads for USB, and other FCs have a dedicated 5V pad for the receiver that powers on with USB while all other 5V pads don't get power. So you need to determine which of those yours FC is.

If your FC doesn't even power up at all from USB at all then you have a different issue such as a blown voltage regulator or Schottky diode.

Delay for the receiver getting power from the FC can vary from FC to FC, so the 2 second wait might be quite normal for that FC. Only someone else with the same FC would be able to confirm that for sure. I don't have one unfortunately.

Thx SnowLeopard! I always appreciate your help. I just confirmed the beep delay is there with or without the rx plugged in. I did not realize that. It seems to work fine on battery. Did a test hover before connecting any vid eqpt to it and it seems to fly.