ESP8266 Community Forum

Hi!
So to begin with I'll explain how everything is connected.
ESP-12E is connected to external power supply (~3.3V)
I use Arduino UNO (powered by USB) as FTDI.
GND ----> GND (3.3V)
VCC ----> 3.3V
CH_PD ----> 3.3V
GPIO15 ----> GND (3.3V)
GPIO2 ----> 3.3V
GPIO0 ----> GND(3.3V)
RXD ----> Logic level converter ----> Arduino RX
TXD ----> Logic level converter ----> Arduino TX

I use Arduino ide 1.6.13 with ESP8266 library to upload code.
In Arduino ide - Board: Generic Esp8266 Module(tried also second Generic ESP8266 and Node MCU 1.0(ESP-12E) )

So the problem is that some time ago I managed to upload something to my esp (and it didn't work ) , but since then I am unable to upload anything and use AT commands. Every time I upload sketch I get this error:

warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed

I don't know whether I'm doing constantly a silly mistake or maybe my esp is just damaged. Also I've searched a lot of forums and run through a lot of websites and none of them seemed to help me.

PS I am not native so sorry for any mistakes in English, I do my best

I got a 12 about a week ago. The only thing I am seeing different from what i do, is I leave GPIO2 unconnected, but maybe that is why I sometimes have trouble. I've had about a 40% success rate in uploading. I always disconnect / reconnect power and reset before uploading. Sometimes it helps to switch to 9600 baud.

V+ to either regulated 3.3 or 5v
GND to GND
CH_PD = 3.3
GPIO0 = GND
GPIO15 = GND
RX to RX
TX to TX
ESP GND to Arduino GND

Having uploaded a sketch, you will no longer be able to use AT commands, because your sketch has replaced the AT command interpreter; so don't worry about that.

Are you sharing the GND line between the external supply, ESP and Arduino?

I'm very new, but isn't Rx of ESP8266 supposed to go to Tx on FTDI/Uno and vice versa?