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200 lines
9.3 KiB
ReStructuredText
200 lines
9.3 KiB
ReStructuredText
Generic ESP8266
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===============
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.. seo::
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:description: Instructions for using generic ESP8266s with ESPHome.
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:image: esp8266.svg
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:keywords: ESP8266
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All ESP8266-based devices are supported by ESPHome. Simply select ``ESP8266`` when
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the ESPHome wizard asks you for your platform and choose a board type
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from `this link <https://registry.platformio.org/platforms/platformio/espressif8266/boards>`__ when the wizard
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asks you for the board type.
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.. code-block:: yaml
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# Example configuration entry
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esphome:
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name: livingroom
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esp8266:
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board: <BOARD_TYPE>
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Many boards have a pin numbering for the exposed pins that is different from the internally used
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ones. ESPHome tries to map the silk-screen pin numbers into the internal pin numbers with a few
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boards, but for generic ESP8266 boards it is often required to just use the internal pin numbers.
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To do this, just prefix all pins with ``GPIO``, for example ``GPIO0`` for the pin with the internal pin
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number 0.
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Some notes on the pins:
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- ``GPIO6`` - ``GPIO11``, ``GPIO0``, ``GPIO2`` and ``GPIO15`` are often already used by the internal
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flash interface and boot mode detection. So it's best to avoid using these pins.
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- ``GPIO17`` additionally has an ADC connected to it. See the :doc:`/components/sensor/adc`
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to read voltages (in the range from 0 to 1.0V) on this pin.
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.. code-block:: yaml
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# Example configuration entry
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esphome:
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name: livingroom
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esp8266:
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board: nodemcuv2
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binary_sensor:
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- platform: gpio
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name: "Pin GPIO17"
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pin: GPIO17
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Special Pins
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------------
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=================== =============================================
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``GPIO0`` Controls Boot Mode
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------------------- ---------------------------------------------
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``GPIO1`` UART TX pin
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------------------- ---------------------------------------------
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``GPIO2`` Controls Boot Mode
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------------------- ---------------------------------------------
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``GPIO3`` UART RX pin
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------------------- ---------------------------------------------
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``GPIO6`` SDIO/Flash CLK pin
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------------------- ---------------------------------------------
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``GPIO7`` SDIO/Flash Data 0 pin
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------------------- ---------------------------------------------
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``GPIO8`` SDIO/Flash Data 1 pin
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------------------- ---------------------------------------------
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``GPIO9`` SDIO/Flash Data 2 pin (qio/qout only)
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------------------- ---------------------------------------------
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``GPIO10`` SDIO/Flash Data 3 pin (qio/qout only)
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------------------- ---------------------------------------------
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``GPIO11`` SDIO/Flash CMD pin
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------------------- ---------------------------------------------
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``GPIO12`` Attached to Hardware SPI controller MISO
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------------------- ---------------------------------------------
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``GPIO13`` Attached to Hardware SPI controller MOSI
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------------------- ---------------------------------------------
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``GPIO14`` Attached to Hardware SPI controller CLK
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------------------- ---------------------------------------------
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``GPIO15`` Controls Boot Mode; Attached to Hardware SPI
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controller CS
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------------------- ---------------------------------------------
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``GPIO16`` Special pin that can be accessed from RTC,
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and is Deep-Sleep wakeup pin
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------------------- ---------------------------------------------
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TOUT aka ``GPIO17`` ADC pin for measuring voltages, can only be
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used as analog input pin
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=================== =============================================
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This means effectively only the following pins can be used as general purpose GPIO:
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========== ============================== ==============================
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**Pin** **Restrictions** **State after Reset**
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---------- ------------------------------ ------------------------------
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``GPIO0`` If HIGH on boot Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO2`` If HIGH on boot Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO4`` High Impedance
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---------- ------------------------------ ------------------------------
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``GPIO5`` High Impedance
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---------- ------------------------------ ------------------------------
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``GPIO6`` Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO12`` Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO13`` Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO14`` Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO15`` If LOW on boot Weak Pull Up
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---------- ------------------------------ ------------------------------
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``GPIO16`` Has pull-down (but no pull-up) Weak Pull Down
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resistor
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========== ============================== ==============================
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Boot Modes
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----------
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On each boot, the ESP8266 will check three pins to determine in which boot mode to enter.
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There are three boot modes:
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========================= ========= ========= ========== ==============
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**Mode** ``GPIO0`` ``GPIO2`` ``GPIO15`` ``boot mode:``
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------------------------- --------- --------- ---------- --------------
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Boot from Flash (normal) HIGH HIGH LOW 3
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------------------------- --------- --------- ---------- --------------
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Download Code from UART LOW HIGH LOW 1
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------------------------- --------- --------- ---------- --------------
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Boot from SD-Card ANY ANY HIGH 4-7
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========================= ========= ========= ========== ==============
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You can identify these on boot-up by looking at the UART output, the first number
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in the ``boot mode:`` line tells you what mode was selected
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.. code-block:: text
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ets Jan 8 2013,rst cause:4, boot mode:(3,6)
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The first lines when viewing the UART logs might have unrecognized characters. This is
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because the effective baudrate of the ESP8266 bootloader is 74800, whereas the program uses 115200.
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Reset Causes
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------------
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Additionally, the first line also contains the **reset cause**.
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These reset causes `are documented
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<https://www.espressif.com/sites/default/files/documentation/esp8266_reset_causes_and_common_fatal_exception_causes_en.pdf>`__:
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== ===================================
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0 Undefined
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-- -----------------------------------
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1 Power On Reboot
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-- -----------------------------------
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2 External reset or deep-sleep wakeup
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-- -----------------------------------
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4 Hardware WDT reset
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== ===================================
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After a software reset, the reset cause will not change.
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Electrical Characteristics
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--------------------------
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=========================================================== =========== =========== =========== ===========
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**Parameter** **Min.** **Typical** **Max.** **Unit**
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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Operating Temperature -40 125 °C
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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Working Voltage ``V_IO`` 2.5 3.3 3.6 V
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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``V_IL`` - INPUT voltage level to be considered LOW -0.3 0.25*V_IO V
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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``V_IH`` - INPUT voltage level to be considered HIGH 0.75*V_IO 3.6 V
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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``V_OL`` - OUTPUT voltage level for LOW 0.1*V_IO V
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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``V_OH`` - OUTPUT voltage level for HIGH 0.8*V_IO V
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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``I_MAX`` - Maximum current for GPIO 12 mA
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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Power Consumption in Deep Sleep 20 µA
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----------------------------------------------------------- ----------- ----------- ----------- -----------
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Power Consumption in Active Mode 120 mA
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=========================================================== =========== =========== =========== ===========
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Source: `ESP8266EX datasheet <https://www.espressif.com/sites/default/files/documentation/0a-esp8266ex_datasheet_en.pdf>`__
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The internal pull up/down resistors have values of 30kΩ to 100kΩ
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(`source <https://bbs.espressif.com/viewtopic.php?t=1079>`__).
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See Also
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--------
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- :doc:`nodemcu_esp8266`
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- :ghedit:`Edit`
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