sensor:
  - platform: template
    name: "${board_name} Heap Size"
    lambda: "return ESP.getFreeHeap();"
    update_interval: 20s
    unit_of_measurement: bytes
    accuracy_decimals: 0
    entity_category: "diagnostic"

  - platform: uptime
    internal: true
    id: uptime_sensor
    update_interval: 60s
    on_raw_value:
      then:
        - text_sensor.template.publish:
            id: uptime_human
            state: !lambda |-
              int seconds = round(id(uptime_sensor).raw_state);
              int days = seconds / (24 * 3600);
              seconds = seconds % (24 * 3600);
              int hours = seconds / 3600;
              seconds = seconds % 3600;
              int minutes = seconds /  60;
              seconds = seconds % 60;
              return (
                (days ? to_string(days) + "d " : "") +
                (hours ? to_string(hours) + "h " : "") +
                (minutes ? to_string(minutes) + "m " : "") +
                (to_string(seconds) + "s")
              ).c_str();

text_sensor:
  - platform: template
    id: uptime_human
    name: "${board_name} Uptime"
    update_interval: never
    icon: mdi:clock-start
    entity_category: "diagnostic"

  - platform: template
    id: last_action
    name: "${board_name} Action"
    update_interval: never
    icon: mdi:clock-time-eight-outline
    entity_category: "diagnostic"