All ESP8266-based devices are supported by ESPHome. Simply select ESP8266 when the ESPHome wizard asks you for your platform and choose a board type from this link when the wizard asks you for the board type.
# Example configuration entryes phome: name: livingroomesp8266: board: <BOARD_TYPE>
Many boards have a pin numbering for the exposed pins that is different from the internally used ones. ESPHome tries to map the silk-screen pin numbers into the internal pin numbers with a few boards, but for generic ESP8266 boards it is often required to just use the internal pin numbers. To do this, just prefix all pins with GPIO, for example GPIO0 for the pin with the internal pin number 0.
Some notes on the pins:
GPIO6 - GPIO11, GPIO0, GPIO2 and GPIO15 are often already used by the internal flash interface and boot mode detection. So it’s best to avoid using these pins.
GPIO17 additionally has an ADC connected to it. See the Analog To Digital Sensor to read voltages (in the range from 0 to 1.0V) on this pin.
# Example configuration entryes phome: name: livingroom esp8266: board: nodemcuv2 binary_sensor: - platform: gpio name: "Pin GPIO17" pin: GPIO17
| GPIO0 | Controls Boot Mode |
| GPIO1 | UART TX pin |
| GPIO2 | Controls Boot Mode |
| GPIO3 | UART RX pin |
| GPIO6 | SDIO/Flash CLK pin |
| GPIO7 | SDIO/Flash Data 0 pin |
| GPIO8 | SDIO/Flash Data 1 pin |
| GPIO9 | SDIO/Flash Data 2 pin (qio/qout only) |
| GPIO10 | SDIO/Flash Data 3 pin (qio/qout only) |
| GPIO11 | SDIO/Flash CMD pin |
| GPIO12 | Attached to Hardware SPI controller MISO |
| GPIO13 | Attached to Hardware SPI controller MOSI |
| GPIO14 | Attached to Hardware SPI controller CLK |
| GPIO15 | Controls Boot Mode; Attached to Hardware SPI controller CS |
| GPIO16 | Special pin that can be accessed from RTC, and is Deep-Sleep wakeup pin |
| TOUT aka GPIO17 | ADC pin for measuring voltages, can only be used as analog input pin |
This means effectively only the following pins can be used as general purpose
GPIO:
| Pin | Restrictions | State after Reset |
| GPIO0 | If HIGH on boot | Weak Pull Up |
| GPIO2 | If HIGH on boot | Weak Pull Up |
| GPIO4 | High Impedance | |
| GPIO5 | High Impedance | |
| GPIO6 | Weak Pull Up | |
| GPIO12 | Weak Pull Up | |
| GPIO13 | Weak Pull Up | |
| GPIO14 | Weak Pull Up | |
| GPIO15 | If LOW on boot | Weak Pull Up |
| GPIO16 | Has pull-down (but no pull-up) resistor | Weak Pull Down |
On each boot, the ESP8266 will check three pins to determine in which boot mode to enter. There are three boot modes:
| Mode | GPIO0 | GPIO2 | GPIO15 | boot mode: |
| Boot from Flash (normal) | HIGH | HIGH | LOW | 3 |
| Download Code from UART | LOW | HIGH | LOW | 1 |
| Boot from SD-Card | ANY | ANY | HIGH | 4-7 |
You can identify these on boot-up by looking at the UART output, the first number in the boot mode: line tells you what mode was selected
ets Jan 8 2013,rst cause:4, boot mode:(3,6)
The first lines when viewing the UART logs might have unrecognized characters. This is because the effective baudrate of the ESP8266 bootloader is 74800, whereas the program uses 115200.
Additionally, the first line also contains the reset cause . These reset causes are documented:
| 0 | Undefined |
| 1 | Power On Reboot |
| 2 |
External reset or deep-sleep wakeup |
| 4 | Hardware WDT reset |
After a software reset, the reset cause will not change.
| Parameter | Min. | Typical | Max. | Unit |
| Operating Temperature | -40 | 125 | °C | |
| Working Voltage V_IO | 2.5 | 3.3 | 3.6 | V |
| V_IL - INPUT voltage level to be considered LOW | -0.3 | 0.25*V_IO | V | |
| V_IH - INPUT voltage level to be considered HIGH | 0.75*V_IO | 3.6 | V | |
| V_OL - OUTPUT voltage level for LOW | 0.1*V_IO | V | ||
| V_OH - OUTPUT voltage level for HIGH | 0.8*V_IO | V | ||
| I_MAX - Maximum current for GPIO | 12 | mA | ||
| Power Consumption in Deep Sleep | 20 | µA | ||
| Power Consumption in Active Mode | 120 | mA |
Source: ESP8266EX datasheet
The internal pull up/down resistors have values of 30kΩ to 100kΩ ( source ).