BM6 BLE battery voltage sensor esphome config

gistfile1.txt

# credit https://github.com/JeffWDH/bm6-battery-monitor/blob/39bb89a095f0714d84d05e595099f28ec44647fe/ESPHome/bm6.yaml

# first you need to find the BLE mac address of the BM6:
esp32_ble_tracker:
text_sensor:
  - platform: ble_scanner
    name: "BLE Devices Scanner"
# read off the mac address in the esphome logs. Device name is just BM6

# then you can configure as follows:

esphome:
  includes:
    - "bm6.h"   # this should be in config/ and contain the following:

#define MBEDTLS_AES_ALT
#include "mbedtls/aes.h"

esp32_ble_tracker:
  scan_parameters:
    continuous: false
    duration: 5s
    
ble_client:
  - id: bm6
    mac_address: 00:00:00:00:00:00 # Put your BM6 address here
    auto_connect: false
    on_connect:
      # Disconnect in case there was a hung connection due to poor signal
      - delay: 15s
      - ble_client.disconnect: bm6

interval:
  - interval: 30min # How often you want to poll the BM6
    then:
      - esp32_ble_tracker.start_scan:
      - delay: 5s
      - esp32_ble_tracker.stop_scan:
      - ble_client.connect: bm6
      - delay: 1s
      - ble_client.ble_write:
          id: bm6
          service_uuid: 0000fff0-0000-1000-8000-00805f9b34fb
          characteristic_uuid: 0000fff3-0000-1000-8000-00805f9b34fb
          value: [0x69, 0x7e, 0xa0, 0xb5, 0xd5, 0x4c, 0xf0, 0x24, 0xe7, 0x94, 0x77, 0x23, 0x55, 0x55, 0x41, 0x14] # Encrypted "d1550700000000000000000000000000" 

sensor:
  - platform: template
    name: "Temperature"
    id: bm6_temperature
    unit_of_measurement: "°C"
    icon: "mdi:thermometer"
    accuracy_decimals: 0

  - platform: template
    name: "Voltage"
    id: bm6_voltage
    unit_of_measurement: "V"
    icon: "mdi:car-battery"
    accuracy_decimals: 2

  - platform: ble_client
    type: characteristic
    ble_client_id: bm6
    name: "bm6"
    service_uuid: 0000fff0-0000-1000-8000-00805f9b34fb
    characteristic_uuid: 0000fff4-0000-1000-8000-00805f9b34fb
    notify: true
    internal: true
    update_interval: never
    lambda: |-
      mbedtls_aes_context aes;
      mbedtls_aes_init(&aes);
      unsigned char output[16];
      unsigned char key[16] = { 108, 101, 97, 103, 101, 110, 100, 255, 254, 48, 49, 48, 48, 48, 48, 57 };
      unsigned char iv[16] = {};
      mbedtls_aes_setkey_dec(&aes, key, 128);
      mbedtls_aes_crypt_cbc(&aes, MBEDTLS_AES_DECRYPT, 16, iv, (uint8_t*)&x[0], output);
      mbedtls_aes_free(&aes);

      int tempC = output[4];
      float volts = ((output[7] << 8) | output[8]) / 100.0f;
      
      if (volts > 0) {
        id(bm6_temperature).publish_state(tempC);
        id(bm6_voltage).publish_state(volts);
        id(bm6).disconnect();
      }
      
      return 0;