Recommended input pins¶
Recommended ESP8266 input pins¶
The following ESP8266 GPIO pins are recommended for as input pins.
- GPIO4
- GPIO5
- GPIO12
- GPIO13
- GPIO14
- GPIO16
The following ESP8266 GPIO pins should be used with caution. There is a risk that the state of the pins can affect the boot sequence. When possible, use other GPIO pins.
- GPIO0 - used to detect boot-mode. Bootloader runs when pin is low during powerup.
- GPIO2 - used to detect boot-mode. Attached to pull-up resistor.
- GPIO15 - used to detect boot-mode. Attached to pull-down resistor.
One pin does not support interrupts.
- GPIO16 - does not support interrupts.
Recommended ESP32 input pins¶
The following ESP32 GPIO pins should be used with caution. There is a risk that the state of the pins can affect the boot sequence. When possible, use other GPIO pins.
- GPIO0 - used to detect boot-mode. Bootloader runs when pin is low during powerup. Internal pull-up resistor.
- GPIO2 - used to enter serial bootloader. Internal pull-down resistor.
- GPIO4 - technical reference indicates this is a strapping pin, but usage is not described. Internal pull-down resistor.
- GPIO5 - used to configure SDIO Slave. Internal pull-up resistor.
- GPIO12 - used to select flash voltage. Internal pull-down resistor.
- GPIO15 - used to configure silencing of boot messages. Internal pull-up resistor.