I'm using an Arduino to realize two "simple" tasks. The Arduino shall receive messages by an 433MHz receiver and send them via ESP8266/ESP-01 to a server. The schematic/wiring plan is attached below.
As you will see, there is a connection between ESP8266's and Arduino's GND. This ist necessary, because otherwise I couldn't get a proper serial connection between them both.
But this connection also "kills" the functionalty of my 433MHz receiver. Once the grounds are linked, I get a "noise" on the 433MHz receiver's data line.
I watched the receivers data line with the poor man's oscilloscope and could see that the receiver starts to output strange signals when the grounds are linked together. I also hooked up the Arduino 5V line on oscilloscope and could that once the grounds are linked, the 5V line isn't "stable" any longer. (It drops one ore more times per seconds from 5V to ~4.7V).
What am I doing wrong? How can I get a proper serial connection between Arduino and ESP8266 without "disturbing" my 433Mhz receiver?
Best Answer
The ESP8266 draws between 40ma and 80mA when connected to a Wifi network but can peak up to around 200mA when transmitting. This sudden drain on the power can cause a voltage drop that may trigger a reset of other devices in the circuit. You should add a large capacitor close to the ESP8266 module. I've used 10uF successfully but you might need more. I would suggest you add one for the 433Mhz module as well.