Ok I figured out, it wasn’t possible. So I bought two pieces of the old Wifi Bee V1 with an Atmega328P. The I2P port on my Grove XBee Carrier works just fine but the IO port doesn’t. Whatever I do, the PD5 pin won’t get HIGH.
Nothing is broken, because I have two XBee Carrier and two Wifi Bees with the same result.
In this sample code, the I2P yellow wire is 3,2V but the IO yellow wire always stays 0V. But VCC -> GND on the IO is as expected 3,3V.
Please give me a hint guys!