The problem started when I tried to upload the Blink program to the module, it uploaded with no issues through Arduino but after that the blue LED didn't blink.

I searched a lot for it and found that the pin number may need to be changed.

So I uploaded this code

int LED0 = 0;
int LED1 = 1;
int LED2 = 2;

void setup() {
  pinMode(LED0, OUTPUT); // Initialize the LED_BUILTIN pin as an output
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  Serial.print("LED_BUILTIN = ");
  Serial.print(LED_BUILTIN, DEC);

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED0, LOW); // Turn the LED on (Note that LOW is the voltage level
  digitalWrite(LED1, LOW); // but actually the LED is on; this is because
  digitalWrite(LED2, LOW); // it is active low on the ESP-01)
  delay(1000); // Wait for a second
  digitalWrite(LED0, HIGH); // Turn the LED off by making the voltage HIGH
  digitalWrite(LED1, HIGH);
  digitalWrite(LED2, HIGH);
  delay(2000); // Wait for two seconds (to demonstrate the active low LED)

to ensure the blinking but still nothing out.

  • After that I tried AT commands and no replies also.
  • After that I did some searches and found that it may need to update the flash program and that's what I did.
  • No sync occurs until I remove and connect the power to the module while the tool is trying to sync. Otherwise, it gives a fail.
  • By removing and connecting the power to the module I was able to upload that flash,
  • But I still have the same problem - no reply from the module to AT commands and the blink output is nothing.

  • Finally I directly connected the TX to the 3.3 V and the blue LED is on so I figured that the problem is in the replying from the module.

Any help would be appreciated.

  • try pin 14. it is one of the used defaults.
    – Juraj
    Jun 30 '18 at 7:47
  • 1
    to put the esp8266 into flashing mode, pin 0 must be low at power-up or reset
    – Juraj
    Jun 30 '18 at 7:52
  • 1
    - tried 14 nothing new Jun 30 '18 at 7:56
  • 1
    also to upload a ketch to the module it has to be low and i did that already Jun 30 '18 at 7:57
  • 1
    i connected it to high to run the sketch but still the same goes Jun 30 '18 at 8:10

Hasn't the ESP8266 got different pin numbering? ie arduino pin 2 = pin 4 on esp8266, arduino pin 3 = pin 5 on esp8266, and arduino pin 4 = pin 2 on esp8266? and pin 4 on esp8266 is the built-in led. hope it helps.

  • NO, this is not true. some dev boars have pin labels and corresponding Dx constants, but not esp-01
    – Juraj
    Jul 12 '18 at 12:01
  • Ah, ok my bad. My reference to a different ESP8266 module. A picture/diagram of the connections would be helpful in finding how this circuit is connected up, don't you think?
    – Clu User
    Jul 15 '18 at 23:30

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