esphome-docs/cookbook/lambda_magic.rst

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Lambda Magic
============
.. seo::
:description: Recipes for various interesting things you can do with Lambdas in ESPHome
:image: language-cpp.svg
Here are a couple recipes for various interesting things you can do with :ref:`Lambdas <config-lambda>` in ESPHome.
These things don't need external or custom components, and show how powerful :ref:`Lambda <config-lambda>` usage can be.
.. _lambda_magic_pages:
Display pages alternative
-------------------------
Some displays like :ref:`lcd-pcf8574` don't support pages natively, but you can easily implement them
using Lambdas:
.. code-block:: yaml
display:
- platform: lcd_pcf8574
dimensions: 20x4
address: 0x27
id: lcd
lambda: |-
switch (id(page)){
case 1:
it.print(0, 1, "Page1");
break;
case 2:
it.print(0, 1, "Page2");
break;
case 3:
it.print(0, 1, "Page3");
break;
}
globals:
- id: page
type: int
initial_value: "1"
interval:
- interval: 5s
then:
- lambda: |-
id(page) = (id(page) + 1);
if (id(page) > 3) {
id(page) = 1;
}
.. _lambda_magic_udp_sender:
Send UDP commands
-----------------
There are various network devices which can be commanded with UDP packets containing command strings.
You can send such UDP commands from ESPHome using a Lambda in a script.
.. code-block:: yaml
script:
- id: send_udp
parameters:
msg: string
host: string
port: int
then:
- lambda: |-
int sock = ::socket(AF_INET, SOCK_DGRAM, 0);
struct sockaddr_in destination, source;
destination.sin_family = AF_INET;
destination.sin_port = htons(port);
destination.sin_addr.s_addr = inet_addr(host.c_str());
// you can remove the next 4 lines if you don't want to set the source port for outgoing packets
source.sin_family = AF_INET;
source.sin_addr.s_addr = htonl(INADDR_ANY);
source.sin_port = htons(64998); // the source port number
bind(sock, (struct sockaddr*)&source, sizeof(source));
int n_bytes = ::sendto(sock, msg.c_str(), msg.length(), 0, reinterpret_cast<sockaddr*>(&destination), sizeof(destination));
ESP_LOGD("lambda", "Sent %s to %s:%d in %d bytes", msg.c_str(), host.c_str(), port, n_bytes);
::close(sock);
button:
- platform: template
id: button_udp_sender
name: "Send UDP Command"
on_press:
- script.execute:
id: send_udp
msg: "Hello World!"
host: "192.168.1.10"
port: 5000
Tested on both `arduino` and `esp-idf` platforms.
.. _lambda_magic_uart_text_sensor:
Custom UART Text Sensor
-----------------------
Lots of devices communicate using the UART protocol. If you want to read
lines from uart to a Text Sensor you can do so using this code example.
With this you can use automations or lambda to set switch or sensor states.
.. code-block:: cpp
#include "esphome.h"
class UartReadLineSensor : public Component, public UARTDevice, public TextSensor {
public:
UartReadLineSensor(UARTComponent *parent) : UARTDevice(parent) {}
void setup() override {
// nothing to do here
}
int readline(int readch, char *buffer, int len)
{
static int pos = 0;
int rpos;
if (readch > 0) {
switch (readch) {
case '\n': // Ignore new-lines
break;
case '\r': // Return on CR
rpos = pos;
pos = 0; // Reset position index ready for next time
return rpos;
default:
if (pos < len-1) {
buffer[pos++] = readch;
buffer[pos] = 0;
}
}
}
// No end of line has been found, so return -1.
return -1;
}
void loop() override {
const int max_line_length = 80;
static char buffer[max_line_length];
while (available()) {
if(readline(read(), buffer, max_line_length) > 0) {
publish_state(buffer);
}
}
}
};
(Store this file in your configuration directory, for example ``uart_read_line_sensor.h``)
And in YAML:
.. code-block:: yaml
# Example configuration entry
esphome:
includes:
- uart_read_line_sensor.h
logger:
level: VERBOSE #makes uart stream available in esphome logstream
baud_rate: 0 #disable logging over uart
uart:
id: uart_bus
tx_pin: D0
rx_pin: D1
baud_rate: 9600
text_sensor:
- platform: custom
lambda: |-
auto my_custom_sensor = new UartReadLineSensor(id(uart_bus));
App.register_component(my_custom_sensor);
return {my_custom_sensor};
text_sensors:
id: "uart_readline"
For more details see :doc:`/custom/uart` and :doc:`/components/uart`.
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.. _lambda_magic_uart_switch:
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Custom UART Switch
------------------
Here is an example switch using the uart text sensor above to set switch state.
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Here we use interval to request status from the device. The response will be stored in uart text sensor.
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Then the switch uses the text sensor state to publish its own state.
.. code-block:: yaml
switch:
- platform: template
name: "Switch"
lambda: |-
if (id(uart_readline).state == "*POW=ON#") {
return true;
} else if(id(uart_readline).state == "*POW=OFF#") {
return false;
} else {
return {};
}
turn_on_action:
- uart.write: "\r*pow=on#\r"
turn_off_action:
- uart.write: "\r*pow=off#\r"
interval:
- interval: 10s
then:
- uart.write: "\r*pow=?#\r"
.. _lambda_magic_rf_queues:
Delaying Remote Transmissions
-----------------------------
The solution below handles the problem of RF frames being sent out by :doc:`/components/rf_bridge` (or
:doc:`/components/remote_transmitter`) too quickly one after another when operating radio controlled
covers. The cover motors seem to need at least 600-700ms of silence between the individual code transmissions
to be able to recognize them.
This can be solved by building up a queue of raw RF codes and sending them out one after the other with
(a configurable) delay between them. Delay is only added to the next commands coming from a list of
covers which have to be operated at once from Home Assistant. This is transparent to the system, which
will still look like they operate simultaneously.
.. code-block:: yaml
rf_bridge:
number:
- platform: template
name: Delay commands
icon: mdi:clock-fast
entity_category: config
optimistic: true
restore_value: true
initial_value: 750
unit_of_measurement: "ms"
id: queue_delay
min_value: 10
max_value: 1000
step: 50
mode: box
globals:
- id: rf_code_queue
type: 'std::vector<std::string>'
script:
- id: rf_transmitter_queue
mode: single
then:
while:
condition:
lambda: 'return !id(rf_code_queue).empty();'
then:
- rf_bridge.send_raw:
raw: !lambda |-
std::string rf_code = id(rf_code_queue).front();
id(rf_code_queue).erase(id(rf_code_queue).begin());
return rf_code;
- delay: !lambda 'return id(queue_delay).state;'
cover:
# have multiple covers
- platform: time_based
name: 'My Room 1'
disabled_by_default: false
device_class: shutter
assumed_state: true
has_built_in_endstop: true
close_action:
- lambda: id(rf_code_queue).push_back("AAB0XXXXX..the.closing.code..XXXXXXXXXX");
- script.execute: rf_transmitter_queue
close_duration: 26s
stop_action:
- lambda: id(rf_code_queue).push_back("AAB0YXXXX..the.stopping.code..XXXXXXXXXX");
- script.execute: rf_transmitter_queue
open_action:
- lambda: id(rf_code_queue).push_back("AAB0ZXXXX..the.opening.code..XXXXXXXXXX");
- script.execute: rf_transmitter_queue
open_duration: 27s
.. _lambda_magic_1button_coover:
One Button Cover Control
------------------------
The configuration below shows how with a single button you can control the motion of a motorized cover
by cycling between: open->stop->close->stop->...
In this example a :doc:`/components/cover/time_based` is used with the GPIO configuration of a Sonoff Dual R2.
.. note::
Controlling the cover to quickly (sending new open/close commands within a minute of previous commands)
might cause unexpected behaviour (eg: cover stopping halfway). This is because the delayed relay off
feature is implemented using asynchronous automations. So every time an open/close command is sent a
delayed relay off command is added and old ones are not removed.
.. code-block:: yaml
esp8266:
board: esp01_1m
binary_sensor:
- platform: gpio
pin:
number: GPIO10
inverted: true
id: button
on_press:
then:
# logic for cycling through movements: open->stop->close->stop->...
- lambda: |
if (id(my_cover).current_operation == COVER_OPERATION_IDLE) {
// Cover is idle, check current state and either open or close cover.
if (id(my_cover).is_fully_closed()) {
id(my_cover).open();
} else {
id(my_cover).close();
}
} else {
// Cover is opening/closing. Stop it.
id(my_cover).stop();
}
switch:
- platform: gpio
pin: GPIO12
interlock: &interlock [open_cover, close_cover]
id: open_cover
- platform: gpio
pin: GPIO5
interlock: *interlock
id: close_cover
cover:
- platform: time_based
name: "Cover"
id: my_cover
open_action:
- switch.turn_on: open_cover
open_duration: 60s
close_action:
- switch.turn_on: close_cover
close_duration: 60s
stop_action:
- switch.turn_off: open_cover
- switch.turn_off: close_cover
Update numeric values from text input
-------------------------------------
Sometimes it may be more confortable to use a :doc:`/components/text/template` to change some numeric values from the user interface.
ESPHome has some nice `helper functions <https://github.com/esphome/esphome/blob/dev/esphome/core/helpers.h>`__ among which
theres's one to convert text to numbers.
In the example below we have a text input and a template sensor which can be updated from the text input field. What the lambda
does, is to parse and convert the text string to a number - which only succeedes if the entered string contains characters
represesenting a float number (such as digits, ``-`` and ``.``). If the entered string contains any other characters, the lambda
will return ``NaN``, which corresponds to ``unknown`` sensor state.
.. code-block:: yaml
text:
- platform: template
name: "Number type in"
optimistic: true
min_length: 0
max_length: 16
mode: text
on_value:
then:
- sensor.template.publish:
id: num_from_text
state: !lambda |-
auto n = parse_number<float>(x);
return n.has_value() ? n.value() : NAN;
sensor:
- platform: template
id: num_from_text
name: "Number from text"
See Also
--------
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- :ref:`config-lambda`
- :ref:`automation`
- :ghedit:`Edit`