---
tags: Home Assistant
---
# Part 4 - Building your own QR code scanner for Home Assistant

##### `Home Assistant` `zewelor/bt-mqtt-gateway` `QR code scanner` `MQTT Tag Scanner`
> [name=Mr. Akashic] [time=Sat, Jun 19, 2021]

## Prerequisites
* Pulling the zewelor/bt-mqtt-gateway image and running the container

## Implementation
本篇所有完整檔案[下載](https://github.com/awlchang/HackMD-Part-4-Building-your-own-QR-code-scanner-for-Home-Assistant.git)。正文開始。

1. 下載[Dockerfile](https://github.com/awlchang/HackMD-Part-4-Building-your-own-QR-code-scanner-for-Home-Assistant/blob/main/Dockerfile)，來準備建立新的image。
2. 在Dockerfile的同一層目錄下執行<span class="dark_orange">docker build -t [NEW_IMAGE_NAME] .</span>指令，會看到開始執行Dockerfile內的指令，如下畫面:

Sending build context to Docker daemon  12.04MB
Step 1/4 : FROM zewelor/bt-mqtt-gateway:latest
 ---> 4d03df950fcb
Step 2/4 : RUN /usr/local/bin/python -m pip install --upgrade pip
 ---> Running in decaa9ac73e6
Requirement already satisfied: pip in /usr/local/lib/python3.8/site-packages (21.0.1)
Collecting pip
  Downloading pip-21.1.3-py3-none-any.whl (1.5 MB)
Installing collected packages: pip
......more

3. 執行<span class="dark_orange">docker images</span>指令，會看到剛建立image。

REPOSITORY                                 TAG         IMAGE ID       CREATED          SIZE
zewelor2/bt-mqtt-gateway                   latest      c7130bee2890   13 seconds ago   321MB

zewelor2/bt-mqtt-gateway就是此篇範例的<span class="dark_orange">NEW_IMAGE_NAME</span>。

4. 新增zewelor2/bt-mqtt-gateway的service到docker-compose.yaml。
:::info
:warning: **注意:**
接下來在5~7的步驟中，所設定的檔案要放在跟docker-compose.yaml內設定的路徑一樣，如下圖。
</div>
:::

5. 在bt-mqtt-gateway的workers資料夾新增QR code掃描器的python檔。直接下載使用[nteumm.py](https://github.com/awlchang/HackMD-Part-4-Building-your-own-QR-code-scanner-for-Home-Assistant/blob/main/nteumm.py)。
6. 新增以下程式碼到bt-mqtt-gateway的gateway.py檔案

import signal
from workers.nteumm import NteummWorker

# Call the device_ungrab function of the NteummWorker for releasing device if it has been already grabbed
def signal_handler(signal, frame):
    print('Stopping')
    NteummWorker.device_ungrab(NteummWorker)
    # dev.ungrab()
    sys.exit(0)

# catch Ctrl + C
signal.signal(signal.SIGINT, signal_handler)

7. 新增以下文字到bt-mqtt-gateway的config.yaml檔案。[完整檔案](https://github.com/awlchang/HackMD-Part-4-Building-your-own-QR-code-scanner-for-Home-Assistant/blob/main/config.yaml)。

nteumm:
  args:
    autodiscovery_prefix: homeassistant
    # topic_prefix: nteumm
    devices:
      nteumm:
        name: Nteumm
        discovery_topic: nteumm/tag_scanned
        discovery_value_template: "{{ value_json.Nteumm.UID }}"
      #如果有兩支QR code掃描器，就新增以下文字。
      #nteumm2:
      #  name: Nteumm2
      #  discovery_topic: nteumm2/tag_scanned
      #  discovery_value_template: "{{ value_json.Nteumm2.UID }}"

8. 執行<span class="dark_orange">docker restart bt-mqtt-gateway</span>指令，重新執行bt-mqtt-gateway服務。
9. 開啟Home Assistant網頁，切換頁面Configuration > Tags，掃描QR code後就會自動顯示在Tags的頁面。以上就完成本篇的紀錄實作。


## Introduction
本篇記錄實作Home Assistant新增來自多個QR code掃描器讀取的QR code。實現的流程順序如下：
1. Raspberry Pi 4上的USB Dongle Bluetooth Receiver收到QR code掃描器讀取的QR code。
2. zewelor/bt-mqtt-gateway服務讀取USB Dongle Bluetooth Receiver收到的QR Code。
3. zewelor/bt-mqtt-gateway服務透過MQTT將第n支掃描器讀取的QR code傳給Home Assistant。
4. Home Assistant透過MQTT收到來自zewelor/bt-mqtt-gateway傳送的QR code並自動新增在網頁上。

### Component and Supplies
* F18W 無線 CMOS 影像式 二維 USB 條碼掃描器
* QR code ([QR Code Generator](https://www.the-qrcode-generator.com/))

### Software Development Tool
* Visual Studio Code

### Runtime Environment
* Raspbian
* Docker container

## Acknowledgements
1. [zewelor/bt-mqtt-gateway](https://github.com/zewelor/bt-mqtt-gateway)
2. [MQTT Tag Scanner](https://www.home-assistant.io/integrations/tag.mqtt/)

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