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Unable to connect to ESP8266 using arduino
We have followed all the steps as per instructed in the tutorial on our PC which uses Windows 7 OS, still we are unable to establish a connection with the WiFi network of the ESP8266 module. The code is getting compiled error free and gets uploaded as well yet the connection establishment step is not executed. 

Arduino Wireless-Connectivity-to-Arduino 10-11 min 10-20 sec 07-02-20, 2:30 p.m. kishanprasad.gunale


Turn off your mobile internet first. And try to connect it again.
07-02-20, 2:50 p.m. Pratikjb11

Even after upload successful if wifi AP not shown in wifi manager of android or windows pc... than ..
Possible Problem :After upload successful GPIO0 still tied to GND pin and RESET pin is not connected to USB to UART Converter hence RESET is not software controlled, ESP8266 is still in bootloader mode and not able to execute firmware.
Solution (Better to say workaround):After successful upload just disconnect GPIO0 from Ground and keep it floating... than press reset button on breadboard... after that esp8266 comes out from bootloader mode and firmware on ESP8266 start executing...
Note: Keeping GPIO0 floating after upload success is poor way to solve problem, Its needed to be pulled up with 1K-4.7K resistor is professional way...

Ravi Butani, Marwadi University, Rajkot
08-02-20, 7:53 p.m. ravi_butani

If ESP-01 is still not able to boot firmware than one more possible problem is poor Power supply decoupling..ESP8266 Draw around 300-350mA current when WiFi Stack enabled and using jumper long wire to powerup ESP-01 will cause dip in voltage when it draws heavy current and goes in to brownout reset mode.. (we observed almost 700mV to 1.1V dip in Voltage due to poor power supply decoupling on scope) may be due to Arduino 3.3V regulator have not enough input output caps, and the ceramic caps used on arduino board is having very high ESR so not able to decouple switching noise properly...

Solution: try to reduce wire length of VCC and GND from Arduino to ESP-01 and if possible add atleast 10uF electrolytic Cap directly between VCC-GND of ESP-01 (Very near to ESP-01)
08-02-20, 8:40 p.m. ravi_butani

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