ESP8266 Community Forum

I have the following setup:

USB-Port1 --> USB-to-Serial-Converter --> RX, TX --> ESP-01 TX, RX
USB-Port2 --> 5V, GND --> LD33V --> VCC/CH_PD, GND

This setup runs fine. I get serial connection at 9600 BAUD and send AT commands.

Now my "problem". If I replace USB-Port2 by an usb powerbank or a 5V USB wall adapter I can see the ESP booting on serial terminal but it doesn't respond to my AT-commands. When I switch back to USB-Port2 all is fine again.

I tested one powerbank (output 2A) and different USB-wall adapters (500ma, 1A, 1.5A) all of them produces the same "error".

GND connection to USB/Serial missing?

Yeah, that's my guess too.

Make sure all grounds are connected, rherrmann. They all need to have the same zero reference. So: USB serial GND to ESP8266 GND to power supply GND.

Thanks! With added ground it works fine. But now I get a new problem. The above described scenario was only for testing purpose. Later I want to use the ESP-01 with an Arduino.

The Arduino shall receive commands by an 433MHz receiver and send them via the ESP-01 to a server. So without the ground between Arduino and ESP-01 I couldn't get a proper serial connection between them both. But now with the linked ground, I get an "noise" on the 5V lines of the Arduino, so that the 433MHz receiver only produces gibberish data signals.