ESP8266 Community Forum

- Thu Oct 08, 2015 1:02 pm #30891 Hi guys,
I'm testing ESP12 with this simple sketch:

Code: Select allvoid setup() {
  // I want GPIO13 as input pin
  pinMode(13, INPUT);
  Serial.begin(115200);
  Serial.println("Started...");
 
}

// the loop function runs over and over again forever
void loop() {
  Serial.println("Hello!");
  delay(3000);              // wait for a second
}

After some successful upload to ESP12 it stopped to communicate through serial!
If power cycle ESP12 in flash mode the serial monitor stays empty (no rubbish chars).
If I press "Upload" on Arduino IDE the blue led of ESP12 makes a bunch of blinks at regular intervals (it doesn't flashes fast like when writing the sketch) and then I get the error "error: espcomm_open failed" on Arduino IDE.

Now I'm no more able to communicate with ESP12 through serial and it can't be reflashed.

Can you help me in finding the trouble?
I never had this issue and I was writing sketches without issues!!

Thanks
Big

Last edited by BigFootIT on Mon Oct 12, 2015 3:55 pm, edited 1 time in total.

- Thu Oct 08, 2015 3:26 pm #30905 When I see these kinds of issues I check really carefully my assumptions on the COM port. For example, do you have another app that has the COM port open as only one app at a time can do that. If you had a second app using the COM port then you would get this kind of error because the IDE can't lock it exclusively.

Another issue would be that the COM port that the IDE is using is not the one that is actually being used by your machine. List your COM ports and see which one is connected to the ESP8266 and check that the IDE thinks it is using that one.

On rare occasion, I have seen the COM port become confused at the OS level and a reboot of your PC might be needed.

Free ESP8266 book available for download here.

- Fri Oct 09, 2015 4:32 am #30936 kolban wrote:
On rare occasion, I have seen the COM port become confused at the OS level and a reboot of your PC might be needed.

I use a cheap PL2303-USB-serial Adapter (reset+flash-button to program) and if the esp-comm hangs i have to reboot my computer with complete poweroff-cycle(Windows XP). The simple restart don't work!
The missed accustic sign (blob) when connect the USB is a hint that the communication with COM-port fails.

- Fri Oct 09, 2015 2:21 pm #30967 Thank you both!

I verified all you suggested about COM and it seems all right.
Sure about COM port I tried connecting an ESP01 (the first ESP8266 I bought) and it worked perfectly.
Then, I tried to connect the ESP12 again and I faced that it still doesn't work, so the issue is situated on ESP12 because COM is working.

ESP12 is soldered on a breadboard adapter, I checked all solders and they seem to be well done.
I tried to cross TX and RX wires (maybe I wired them wrong, I said) but I got the same behavior then before: trying to write a sketch I see the blue led blinking slowly 5 or 6 times at regular intervals (half second on, half second off) and then fails.

Sincerely, I think that I've broken something on ESP12