| Mode | GPIO0 | GPIO2 | GPIO1 (TX) | |------|-------|-------|-------------| | | 0 | 1 | 1 | | Flash Boot (Normal Run) | 1 | 1 | 1 | | SDIO Boot | 0 | 1 | 0 |
There are 8 pins total:
The ESP-01 does not break out the GPIO16 pin (RTC wake-up), so deep-sleep is not possible without soldering to the chip itself. For battery operation, consider an ESP-01S or Wemos D1 Mini instead. esp8266 esp-01 datasheet