Global Variables

In some cases you might need to share a global variable across multiple lambdas. For example, global variables can be used to store the state of a garage door.

 # Example configuration entry
   - id: my_global_int
     type: int
     restore_value: no
     initial_value: '0'
   # Example for global string variable
   - id: my_global_string
     type: std::string
     restore_value: yes
     max_restore_data_length: 24
     initial_value: '"Global value is"'

# In an automation
    - lambda: |-
        if (id(my_global_int) > 5) {
          // global value is greater than 5
          id(my_global_int) += 1;
        } else {
          id(my_global_int) += 10;

        ESP_LOGD(TAG, "%s: %d", id(my_global_string).c_str(), id(my_global_int));

Configuration variables:

  • id (Required, ID): Give the global variable an ID so that you can refer to it later in lambdas.

  • type (Required, string): The C++ type of the global variable, for example bool (for true/false), int (for integers), float (for decimal numbers), int[50] for an array of 50 integers, etc.

  • restore_value (Optional, boolean): Whether to try to restore the state on boot up. Be careful: on the ESP8266, you only have a total of 96 bytes available for this! Defaults to no.

  • max_restore_data_length (Optional, integer): Only applies to variables of type std::string. ESPHome will allocate enough space for this many characters, plus single character of overhead. Strings longer than this will not be saved. The max value of this variable is 254 characters, and the default is 63 characters.

  • initial_value (Optional, string): The value with which to initialize this variable if the state can not be restored or if state restoration is not enabled. This needs to be wrapped in quotes! Defaults to the C++ default value for this type (for example 0 for integers).

globals.set Action

This Action allows you to change the value of a global variable without having to use the lambda syntax.

  - globals.set:
      id: my_global_var
      value: '10'

Configuration variables:

  • id (Required, ID): The ID of the global variable to set.

  • value (Required, templatable): The value to set the global variable to.


This action can also be written in lambdas:

id(my_global_var) = 10;

See Also