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125 lines
3.1 KiB
ReStructuredText
125 lines
3.1 KiB
ReStructuredText
Custom UART Text Sensor
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=======================
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.. seo::
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:description: Instructions for setting up a custom uart text sensor.
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:image: language-cpp.png
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Lots of devices communicate using the UART protocol. If you want to read
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lines from uart to a Text Sensor you can do so using this code example.
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With this you can use automations or lambda to set switch or sensor states.
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.. code-block:: cpp
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#include "esphome.h"
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class UartReadLineSensor : public Component, public UARTDevice, public TextSensor {
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public:
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UartReadLineSensor(UARTComponent *parent) : UARTDevice(parent) {}
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void setup() override {
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// nothing to do here
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}
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int readline(int readch, char *buffer, int len)
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{
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static int pos = 0;
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int rpos;
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if (readch > 0) {
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switch (readch) {
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case '\n': // Ignore new-lines
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break;
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case '\r': // Return on CR
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rpos = pos;
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pos = 0; // Reset position index ready for next time
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return rpos;
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default:
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if (pos < len-1) {
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buffer[pos++] = readch;
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buffer[pos] = 0;
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}
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}
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}
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// No end of line has been found, so return -1.
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return -1;
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}
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void loop() override {
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const int max_line_length = 80;
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static char buffer[max_line_length];
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if (available() && readline(read(), buffer, max_line_length) > 0) {
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publish_state(buffer);
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}
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}
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};
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(Store this file in your configuration directory, for example ``uart_read_line_sensor.h``)
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And in YAML:
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.. code-block:: yaml
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# Example configuration entry
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esphome:
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includes:
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- uart_read_line_sensor.h
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logger:
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level: VERBOSE #makes uart stream available in esphome logstream
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baud_rate: 0 #disable logging over uart
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uart:
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id: uart_bus
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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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text_sensor:
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- platform: custom
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lambda: |-
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auto my_custom_sensor = new UartReadLineSensor(id(uart_bus));
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App.register_component(my_custom_sensor);
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return {my_custom_sensor};
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text_sensors:
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id: "uart_readline"
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Example usage
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-------------
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Here is an example switch using the uart text sensor to set switch state.
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Here we use interval to request status from the device. The reponse will be stored in uart text sensor.
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Then the switch uses the text sensor state to set its own state.
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.. code-block:: yaml
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switch:
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- platform: template
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name: "Switch"
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lambda: |-
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if (id(uart_readline).state == "*POW=ON#") {
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return true;
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} else if(id(uart_readline).state == "*POW=OFF#") {
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return false;
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} else {
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return {};
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}
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turn_on_action:
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- uart.write: "\r*pow=on#\r"
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turn_off_action:
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- uart.write: "\r*pow=off#\r"
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interval:
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- interval: 10s
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then:
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- uart.write: "\r*pow=?#\r"
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See Also
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--------
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- :doc:`/components/uart`
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- :doc:`/custom/uart`
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- :ghedit:`Edit`
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