DC motor: 3-6v 
Servo sg90: 3-7.2v
Esp 8266 01: 3.3v

I have 2 Arduino Uno both has their own ac-dc power adapter. Lets say, 1st Arduino is Ard1 and 2nd is Ard2.

The Ard1 communicates to a web server (BLYNK) with Esp 01.

Using I2C, Ard1 sends command to Ard2 to power/move the DC motor/Servo.

So far, it has no problem operating with Servo. But,

Whenever the Ard1 commands the Ard2 to power the DC motor.

Right when the DC motor runs(using digitalWrite(motor,HIGH)) the Esp 01 resets.

  • Tried using analogWrite(motor, 102) though it won't reset instantly, prolong usage randomly resets it anytime.

  • I also tried to test operating Servo and DC motor simultaneously in Ard2 using Serial commands, without I2C/Esp01. There was no problem at all, both works flawlessly.

Below is the diagram of the wiring. enter image description here

  • That‘s an electronic issue. You should post a circuit diagram or move this question to electronics SE – Sim Son Feb 15 '20 at 6:20
  • You should check the current rating for motor. It may be the case that your supply is not able to provide it. – brtiberio Feb 15 '20 at 10:36
  • How is the ESP-01 powered/? – Majenko Feb 15 '20 at 13:28
  • I've just included a diagram for further understanding. Please pardon me, I have zero knowledge on electronics/electrical. – Kolokoy Feb 16 '20 at 5:02
  • Despite the fact that you don‘t have pull-ups connected to the I2C lines your circuit looks fine. How do you know that the esp resets, what did you observe? – Sim Son Feb 16 '20 at 7:12

Can you clear one thing that you are giving power to dc motor from 5v pin given on Arduino board or from your ac to dc power supply. If you are giving power to the motor from 5v pin of Arduino Uno then there is a high possibility that the motor is not getting sufficient current because 5v supply on Arduino comes from onboard lm1117 5v voltage regulator and cheap clon Arduino has a cheap regulator with less than 1amp capacity.

  • It was indeed. I then resorted to a 9v battery supply for dc however problem still exist but not that severe, it still cuts the connection. Finally, my latest solution was attaching a 10ko resistor between esp's ch_d to 3.3v of arduino and 1k between gnd and esp's rx and another 1k between esp's rx to arduino's. So far everything went well. – Kolokoy Feb 17 '20 at 14:44
  • @Kolokoy what are These resistors supposed to do?! Note that a 9V battery is also a bad choose as I can‘t provide much current as well. You better use a proper PSU or e.g a Li-Ion battery – Sim Son Feb 18 '20 at 16:25
  • Someone I knew said rx/tx might uses a TTL logic level of 5v instead of 3.3v which the esp 01 can only take. I also found a tutorial on YouTube on the wiring of esp01 to arduino and followed it. The battery was just to test if problem would still exist when the dc motor has different power supply, I will not use it in the final outcome. – Kolokoy Feb 18 '20 at 23:45

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