I can't flash my ESP8266 (ESP-01). I have 3.3 V and ground connected, Rx to Tx and Tx to Rx on my USB to serial adapter. I also have GPIO0 connected to ground too.
I am using an external power supply but the USB adapter and power adapter share a common ground.
I'm using a Mac and ESP tools to flash it, and it has worked before.
The command I am using is:
sudo ./esptool.py --port /dev/tty.wchusbserial1410 write_flash 0x00000 AT22SDK10020150320boot12.bin
But the response is:
A fatal error occurred: Failed to connect to ESP8266
This make me think something is wrong with receiving data from the ESP because when attempting to connect, the ESP's blue LED flashes.
My USB to serial adapter works fine though as I've tested it with my Arduino.