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I am trying to send AT commands to esp-01 through serial monitor I have uploaded a blank sketch to Arduino , whatever command I send to ESP I get reply ERROR. After reconnecting esp-01 I got some garbage vales then ready. Can anyone help me what I am doing wrong. This is what I got on serial monitor this is what I am getting on serial monitor

These are the connections I am using, I tried to use voltage divider but after using voltage divider, Esp's blue led turned on and nothing happened so I used just used the resistors in series between TX and TX of both devices

CONNECTIONS

This is the voltage divider circuit I was using(that didn't worked)

voltage divider circuit

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  • Please upload your code so it can be examined against the results you are getting.
    – Nino
    Jul 15 at 7:52
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    did you set line ends in Serial Monitor to "Both"?
    – Juraj
    Jul 15 at 8:45
  • you want a voltage divider on receiver pin of esp8266. the RX pin of the board is TX pin of the USB chip (because the USB chip is connected to ATmega RX to TX)
    – Juraj
    Jul 15 at 8:46
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The hardware serial, pins 1 and 2, are used by the Arduino to communicate to the USB adapter to your computer. When you connect another device to them, it interferes with the communication between your computer and the Arduino.

The solution is to connect the ESP-01 to another set of pins and use the SoftwareSerial library to create a second serial port for it. The code then needs to listen on both serial ports and move data between them.

Also, you need to use the voltage divider or you risk burning out the input pin. To make the voltage divider, connect the Arduino output to the top of the divider and the ESP-01 to the middle. You appear to have those reversed in your schematic.

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    here the USB chip of Uno is connected to the esp8266 and the ATmega is inactive
    – Juraj
    Jul 15 at 9:42
  • The paragraph about the voltage divider regarding Rx is relevant though:To make the voltage divider, connect the Arduino RX0 to the top of the divider and the ESP-01 RXD to the middle. You appear to have those reversed in your schematic. Jul 15 at 12:04
  • Sometime when I connect CH-PD to 3.3v, SP flash IC starts getting hotter and nothing works can you tell me what causing that ? Jul 17 at 10:27

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