The ESP-01 is the perfect tool for one specific job: Turning "dumb" serial devices into smart devices.
But trying to use an ESP-01 without consulting its datasheet is like trying to fly a drone in the dark. You might get it off the ground, but you’re going to crash. esp-01 datasheet
| Mode | GPIO 0 | GPIO 2 | GPIO 15 (TXD) | | :--- | :--- | :--- | :--- | | | LOW | HIGH | LOW | | Flash Boot (Run Code) | HIGH | HIGH | LOW | The ESP-01 is the perfect tool for one
Pro Tip: Keep a PDF of the ESP8266EX Technical Reference Manual on your desktop. You won't read all of it, but you will search for "Deep Sleep" and "GPIO" a thousand times. | Mode | GPIO 0 | GPIO 2