PC unable to connnect to Feather HUZZAH ESP8266 Moderators: adafruit_support_bill, adafruit

[lzemail]

Product: https://www.adafruit.com/product/3046

The esp8266 worked for a few hours(I tested with LED blink and other sketches). Then next day, Arduino IDE is unable to connect the serial port (COM6 in my case, same USB cable) while trying to upload a sketch to the esp8266, showing:

Serial port COM6
Connecting........_____....._____....._____....._____....._____....._____.....____
esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

The PC (Windows 10) Device Manager shows "Silicon Labs CP210x USB to UART Bridge (COM6)" when the esp8266 is connected to the PC via the USB cable.

Any advice / ideas would be greatly appreciated.

[ashleyjames]

Try to remove or to forget the driver in Windows Device Manager. Then reconnect. I hope it helps

[lzemail]

Thanks for suggestion.

I don't see an option to remove the driver in the Device Manager. When I disconnect the USB cable (i.e. disconnect esp8266 from PC), that COM6 line ("Silicon Labs CP210x USB to UART Bridge (COM6)" disappears.

I also tried on two other Windows 10 computers, same error/result -- unable to connect to esp8266.

[lzemail]

Issue resolved.

The problem appears to be caused by the esp8266's pin#15 being pulled high during startup when the pin#15 is connected to a logic level shifter. I was using a level shifter to interface a 5v sensor with the esp8266 (3.3v).

According to https://learn.adafruit.com/adafruit-fea ... 66/pinouts, "GPIO #15, is also used to detect boot-mode. It has a pulldown resistor connected to it, make sure this pin isn't pulled high on startup."

Thanks.