Problems while flashing ESP12E

Projects General Guidance
1

I use the following circuit to flash my ESP12E -> see attachement. The flashing works (baudrate 115200, Board: NodeMCU 1.0 (ESP-12E Module)), but the program won't start. All i get is a cryptic output in my serial monitor when i reset the ESP12E.

So my flashing-sequence is the following:

GPIO0 is connected to GND
-> Flash (Blink example with a serial.println("Test"); in void loop() to see something in serial monitor), whichs works
-> disconnect GPIO0 from GND
-> opening serial monitor and see nothing
-> connecting RST to GND and get cryptic output (see attachement). Also the LED isn't blinking.

Someone knows this issue? I'll get exactly 3.3V at my ESP12E-VCC (generally speaking on the whole 'red line' in the first attachement).

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  Serial.println("Test");
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

ESP12E-Grundschaltung.png
ESP12E-Grundschaltung.png1000×609 254 KB

crypt.png
crypt.png1000×108 8.16 KB

2

You forgot to add a Serial.begin() statement to your setup(). See:

3

Well, thanks. That was easy.

Weird, why does this work without Serial.begin() when i work with a breakout board (for example NodeMCU Esp8266)?

4

I don't know, I've never tried to get by without Serial.begin(). Maybe someone with more understanding of the innards of the ESP8266 HardwareSerial library will comment. I know the ESP8266 bootloader does spew out some stuff on Serial at 74880 baud and you get a crash dump at any baud rate, then some other stuff printed at 115200, so maybe it's already initialized from some of that.

5

bootloader printout baud rate depends on oscilator frequency. 74880 baud is it for 26 MHz. 115200 for 40MHz oscilator.