Send AT commands to ESP8266 from Arduino Nano serial monitor I have an Arduino nano and an ESP8266-01.

The first thing to do seems to be to send AT commands via the serial monitor and see the replies.

ESP connect as follows:

  GND   GND   
  GPIO2 not connected
  GPIO0 not connected
  RX    to Arduino RX via level shifter
  TX    to Arduino TX via level shifter
  CHPD  3.3V
  RST   3.3V
  VCC   3.3V


Image of breadboard (imgur rejects)
https://www.dropbox.com/s/aif8afi29amy02h/20180807_135218.jpg?dl=0

When connecting the red light comes on and the blue light flashes quickly (and the Arduino RX light flashes with it) then goes out.

Here is the sketch I'm using. (The ESP8266 must be disconnected from RX+TX for uploading of the sketch to work.)

     void setup() { 
  Serial.begin(115200); 

  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, HIGH); 
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH); 
  delay(250);
  digitalWrite(LED_BUILTIN, LOW);
  delay(3000);
 }


(I like to blink the LED to demonstrate that uploading worked.)

With the serial monitor set to 115200 (NL&amp;CR) I sent AT and nothing happens.

What have I got wrong? I really don't understand! Thanks in advance for any suggestions.

(This is actually my third ESP8266. The first worked fine on 5V but stopped working after I set the baud rate to 9600. I presume 5V killed it but it's strange that it worked for so long. The second, connected as above, when powered up made that power supply red hot and melted the jumpers.)
First problem is that io 0 of the esp8266 must be pulled HIGH for normal boot. With io 0 not HIGH, the esp8266 starts in flashing mode.

Your other problem is the reset pin connection. It must be connected with pull-up resistor or not connected.

See ESP8266 Hardware Design Guidelines


  Pin32 serves as an RST pin which can be left floating when it is not
  used. The reset pin is held low when the chip is enabled. In order to
  avoid resets caused by external interference, the lead is generally
  required to be short, and no external pull-up resistor is necessary


I suspect that "The reset pin is held low when the chip is enabled." is a bad translation. They say in pin description "32 EXT_RSTB I External reset signal (Low voltage level: Active)". What they mean is that the chip resets when reset pin is set LOW.