ESPHome-based data exchange between nodes over BLE

ble_address.h

#include "esphome.h"
#include <BLEDevice.h>


class BleAddress : public PollingComponent, public TextSensor {
 public:
  // constructor
  BleAddress() : PollingComponent(15000) {}

  float get_setup_priority() const override { return esphome::setup_priority::LATE; }

  void setup() override {
    // This will be called by App.setup()
  }
  void update() override {
    publish_state(BLEDevice::getAddress().toString());
  }
};

client.yaml

esphome:
  name: ${client_name}

# ...common config omitted for brevity...

# Apparently it's required by ble_client component defined below
esp32_ble_tracker:

ble_client:
  - mac_address: !secret server_ble_mac # read it from server logs
    id: ble_server

text_sensor:
  - id: ble_time
    name: "Time Retrieved over BLE"
    platform: template
  - id: ble_kitchen_co2
    name: "Kitchen CO2 over BLE"
    platform: template

# For some reasons, there is only BLE sensor, and there is no BLE text_sensor in ESPHome as of today
# Tha being said, it allows executing custom code upon rertieving the data over BLE
# But by default it just only consumes the 1st bye.
# Here we repeatedly employ a pattern where we define sensors that always would return 0,
# but as a side-effect it actually retrieves the entire string over BLE and pushes it into one of text sensors above.
# Such hacks are not needed for numbers, obviously.
sensor:
  - name: "Time read over BLE"
    platform: ble_client
    ble_client_id: ble_server # refer to the conenction to the server defined above
    service_uuid: !secret ble_service # here and below, using !secret for easy cross-config value sharing
    characteristic_uuid: !secret ble_characteristic_time
    # Here we actually do the magic of consuming value read over BLE as `x`,
    # converting it to a string, and then pushing it into the proper text_sensor defined above.
    # Then we return 0 just so that this particular sensor instance is happy.
    lambda: |-
      std::string value(x.begin(), x.end());
      id(ble_time).publish_state(value);
      return 0;
      
  - name: "Kitchen CO2 read over BLE"
    platform: ble_client
    ble_client_id: ble_server # refer to the conenction to the server defined above
    service_uuid: !secret ble_service # here and below, using !secret for easy cross-config value sharing
    characteristic_uuid: !secret ble_characteristic_kitchen_co2
    # Here we actually do the magic of consuming value read over BLE as `x`,
    # converting it to a string, and then pushing it into the proper text_sensor defined above.
    # Then we return 0 just so that this particular sensor instance is happy.
    lambda: |-
      std::string value(x.begin(), x.end());
      id(ble_kitchen_co2).publish_state(value);
      return 0;

server.yaml

esphome:
  name: ${server_name}
  includes:
    - ble_address.h # Tiny custom sensor providing us with BLE MAC address we'd need to configure client
    
# ...common config omitted for brevity...
    
external_components:
  - source: github://wifwucite/esphome-ble-controller # Amazing component that exports ESP sensors as BLE services

time:
  - platform: homeassistant
    id: ntp

text_sensor:
  - platform: custom
    lambda: |-
      auto ble_address = new BleAddress();
      App.register_component(ble_address);
      return {ble_address};
    text_sensors:
      id: ble_address
      internal: True
      on_value:
        then:
          - lambda: |-
              ESP_LOGD("main", "BLE Address is: %s", x.c_str());
      
  - id: timestamp
    name: "Timestamp"
    platform: template
    update_interval: 10s
    lambda: |-
      return id(ntp).now().strftime("%Y-%m-%dT%H:%M:%S");
      
  # Import from HA
  - id: kitchen_co2
    name: "Kitchen CO2"
    platform: homeassistant
    entity_id: sensor.kitchen_co2_scd30

  
esp32_ble_controller:
  security_mode: none  # https://esphome.io/components/sensor/ble_client.html doesn't support security
  on_connected:
    - component.update: timestamp # make sure time most recent whenever someone connects
    
  services:
    - service: !secret ble_service # here and below, using !secret for easy cross-config value sharing
      characteristics:
        - characteristic: !secret ble_characteristic_time
          exposes: timestamp
        - characteristic: !secret ble_characteristic_kitchen_co2
          exposes: kitchen_co2