59 lines
2.2 KiB
ReStructuredText
59 lines
2.2 KiB
ReStructuredText
.. _uart:
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UART Bus
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========
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.. seo::
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:description: Instructions for setting up a UART serial bus on ESPs
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:image: uart.png
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:keywords: UART, serial bus
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UART is a common serial protocol for a lot of devices. For example, when uploading a binary to your ESP
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you have probably used UART to access the chip. UART (or for Arduino often also called Serial) usually
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consists of 2 pins:
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- **TX**: This line is used to send data to the device at the other end.
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- **RX**: This line is used to receive data from the device at the other end.
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Please note that these the naming of these two pins depends on the chosen perspective and can be ambiguous. For example,
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while the ESP might send (``TX``) on pin A and receive (``RX``) data on pin B, from the other devices
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perspective these two pins are switched (i.e. *it* sends on pin B and receives on pin A). So you might
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need to try with the two pins switched if it doesn't work immediately.
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Additionally, each UART bus can operate at different speeds (baud rates), so esphomelib needs to know what speed to
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receive/send data at using the ``baud_rate`` option. The most common baud rates are 9600 and 115200.
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In some cases only **TX** or **RX** exists as the device at the other end only accepts data or sends data.
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.. note::
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On the ESP32, this component uses the hardware UART units and is thus very accurate. On the ESP8266 however,
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esphomelib has to use a software implementation as there are no other hardware UART units available other than the
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ones used for logging. Therefore the UART data on the ESP8266 can have occasional data glitches especially with
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higher baud rates..
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.. code-block:: yaml
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# Example configuration entry
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uart:
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tx_pin: D0
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rx_pin: D1
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baud_rate: 9600
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Configuration variables:
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------------------------
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- **baud_rate** (**Required**, int): The baud rate of the UART bus.
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- **tx_pin** (*Optional*, :ref:`config-pin`): The pin to send data to from the ESP's perspective.
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- **rx_pin** (*Optional*, :ref:`config-pin`): The pin to receive data on from the ESP's perspective.
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- **id** (*Optional*, :ref:`config-id`): Manually specify the ID for this UART hub if you need multiple UART hubs.
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See Also
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--------
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- :apiref:`uart_component.h`
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- :ghedit:`Edit`
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.. disqus::
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