Lambda Magic¶
Here are a couple recipes for various interesting things you can do with Lambdas in ESPHome. These things don’t need external or custom components, and show how powerful Lambda usage can be.
Display pages alternative¶
Some displays like lcd_pcf8574 Component don’t support pages natively, but you can easily implement them using Lambdas:
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;
}
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.
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.
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.
#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:
# 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 Custom UART Device and UART Bus.
Custom UART Switch¶
Here is an example switch using the uart text sensor above to set switch state.
Here we use interval to request status from the device. The response will be stored in uart text sensor. Then the switch uses the text sensor state to publish its own state.
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"
Delaying Remote Transmissions¶
The solution below handles the problem of RF frames being sent out by RF Bridge Component (or 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.
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
Update numeric values from text input¶
Sometimes it may be more confortable to use a Template Text to change some numeric values from the user interface. ESPHome has some nice helper functions 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.
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"