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I would like to connect an Arduino Uno and an ESP 01 module. I use the Arduino IDE and I tried to test communication via serial monitor. I get the "ready" message from the ESP 01, but I am not able to issue AT commands from the serial monitor. It only displays random characters on the console.

It seems that no newline character is issued, because if I try to insert commands, they are inserted next to previous characters. I use "Both NL & CR" and 115200 baud settings in Arduino IDE. I tried 9600 baud too, but then the text is unreadable.

I used the following pins on my ESP-01:

Vcc -> 3,3V
Gnd -> Gnd
Rx  -> Tx(pin 0) of my Arduino, used voltage divider to make it 3.3V.
Tx  -> Rx(pin 1) of Arduino
CH_PD -> 3.3V

Please see serial monitor screenshot: enter image description here

EDIT: PROBLEM RESOLVED:

My Arduino is connected to my PC via USB, so I changed pins for communication with the ESP by SoftwareSerial to pins 10 and 11. Now it works. Thank you.

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2 Answers 2

Reset to default
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Just to have an answer instead of just an edit/addition to the question:

EDIT: PROBLEM RESOLVED:

My Arduino is connected to my PC via USB, so I changed pins for communication with the ESP by SoftwareSerial to pins 10 and 11. Now it works. Thank you.

Ok... sure... your Uno's Atmega384 was talking with pins 0 and 1 to the USB adaper chip (Atmega16u2 on Uno R3) and at the same time to the ESP-01.

Read the fine schematic: Arduino Uno R3

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It could be the case, that the Arduino power supply is insufficient.

"[...] note that the Arduino 3.3V regulated output (50 mA max) can't drive the current requested by the ESP (Up to 200 mA). Some tutorials on the Internet use the Arduino 3.3V to power the ESP, but it didn't worked for me. I'm using an external power supply (An old 5V Android charger)."Source

Possible, that the power consumption was within range when the readable text was printed and too high when all the unreadable stuff was sent.

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  • Tried to use power supply with 3,3V / up to 1A and now and received only random characters instead of "ready"message :(
    – n0hepe
    Commented Jul 10, 2016 at 12:41
  • Also, I inserted power source directly to Vcc pin of ESP, didnt uset any kind of diode/stabilizator etc, this could problem maybe?
    – n0hepe
    Commented Jul 10, 2016 at 13:03
  • Also, my voltage divider is: 3300 Ohm and 6600 Ohm, not sure if this is ok :x
    – n0hepe
    Commented Jul 10, 2016 at 13:21

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