# Wireless Lab 1 * 實驗環境 * 硬體版本 : Raspberry Pi 3 Model B+ * 作業系統 : Raspbian 2018-06-27 * LoRa : SX1276晶片 * 實驗目標 * 使用ABP模式傳輸資料 * 並用MQTT取得資料後解碼 ###### tags: `Wireless` ## :star: 實驗結果 1. 跑完ABP傳輸模式的流程，傳輸資料時分別使用`Confirm Data`和`Unconfirm Data`，截圖樹莓派上的結果，應該會有一個是有ACK一個是沒有ACK的。 2. 傳輸資料後用MQTT查看，並用base64解密截圖。 3. **以組為單位(一個人上傳即可)**，將這些截圖結果貼成一個word檔案，命名為`wireless-lab1-groupxx.docx`，並上傳到LMS作業區。 ## ABP模式送出 (send_ttn.py) 這份程式主要修改來自 [jeroennijhof](https://github.com/jeroennijhof/LoRaWAN) 的程式碼 * 將[實驗程式碼](https://github.com/Ox7FFFFFFF/Wireless-Lab1)載下來 ```shell $ git clone https://github.com/Ox7FFFFFFF/Wireless-Lab1 ``` * 程式資料夾 <i class="fa fa-folder-open"></i> LoRaWAN - 與LoRaWAN相關的程式 <i class="fa fa-folder-open"></i> SX127x - 控制晶片的SPI程式 <i class="fa fa-file-text"></i> send_ttn.py - 資料送出 (主程式) <i class="fa fa-file-text"></i> config.json - Activated [DevAddr, NwkSKey, AppSKey]配置 * 程式流程 ```flow st=>start: Start tx=>operation: MODE.TX send=>operation: send message tx_done=>operation: TX_DONE rx=>operation: MODE.RXSINGLE read=>operation: Read downlink payload save=>operation: Save fCnt to config.json cond=>condition: MIC check vaild rx_done=>operation: RX_DONE drop=>opertion: pass message success=>operation: Success fail=>operation: Fail e=>end: End st->tx->send->tx_done->tx_done->rx->rx_done->read->cond cond(yes)->success->save cond(no)->fail->save save->e ``` 1. 將devAddr,nwkSKey,appSKey填入`config.json`中，各組別的key在[這裡](https://docs.google.com/spreadsheets/d/1m-1YNfDqTG7ANa1yWgwECjDgPu3QftA0OFzzmewLcI0/edit#gid=958303526) ```json { "//":"請填寫自己組別對應的內容" "appskey": "ede9e85656d0632a2fd197cddecb8ebf", "devaddr": "06bdb47f", "fCnt": 0, "nwskey": "1917da8b8be11daf804c700298720299" } ``` 3. 調整`send_ttn.py`主要參數 * Frequency * Spreading Factor * Bandwidth ``` python=114 # Setup lora.set_mode(MODE.SLEEP) lora.set_dio_mapping([1,0,0,0,0,0]) lora.set_freq(AS923.FREQ1) lora.set_spreading_factor(SF.SF7) lora.set_bw(BW.BW125) lora.set_pa_config(pa_select=1) lora.set_pa_config(max_power=0x0F, output_power=0x0E) lora.set_sync_word(0x34) lora.set_rx_crc(True) ``` 4. fCnt 要隨著傳輸次數增加，Server端收到小於目前記錄的fCnt將會丟棄封包不處理。 ```python=56 def send(self): global fCnt lorawan = LoRaWAN.new(nwskey, appskey) message = "HELLO WORLD!" # 資料打包,fCnt+1 lorawan.create(MHDR.CONF_DATA_UP, {'devaddr': devaddr, 'fcnt': fCnt, 'data': list(map(ord, message)) }) print("fCnt: ",fCnt) print("Send Message: ",message) fCnt = fCnt+1 self.write_payload(lorawan.to_raw()) self.set_mode(MODE.TX) ``` 5. 當切換到`MODE.TX`時,送出uplink之後會跳到`on_tx_done` ```python=21 def on_tx_done(self): print("TxDone\n") # 切換到rx self.set_mode(MODE.STDBY) self.clear_irq_flags(TxDone=1) self.set_mode(MODE.SLEEP) self.set_dio_mapping([0,0,0,0,0,0]) self.set_invert_iq(1) self.reset_ptr_rx() sleep(1) self.set_mode(MODE.RXSINGLE) ``` 6. 當接收到downlink時，會跳到`on_rx_done` ```python= def on_rx_done(self): global RxDone RxDone = any([self.get_irq_flags()[s] for s in ['rx_done']]) print("RxDone") self.clear_irq_flags(RxDone=1) # 讀取 payload payload = self.read_payload(nocheck=True) lorawan = LoRaWAN.new(nwskey, appskey) lorawan.read(payload) print("get mic: ",lorawan.get_mic()) print("compute mic: ",lorawan.compute_mic()) print("valid mic: ",lorawan.valid_mic()) # 檢查mic if lorawan.valid_mic(): print("ACK: ",lorawan.get_mac_payload().get_fhdr().get_fctrl()>>5&0x01) print("direction: ",lorawan.get_direction()) print("devaddr: ",''.join(format(x, '02x') for x in lorawan.get_devaddr())) write_config() else: print("Wrong MIC") ``` 7. 執行`send_ttn.py` ```shell $ python3 send_ttn.py ``` ![](https://i.imgur.com/THnUuyT.png) * MIC(Message Integrity Check): * 用來確認這個資料是不是自己的 * ACK(Acknowledge): * 因為傳送的資料格式是`MHDR.CONF_DATA_UP`，所以Downlink中會有ACK回應 * Direction: * Uplink : 0 * Downlink : 1 * devaddr * 也可以確認一下devaddr看是不是自己的，採用[Little-Endian](https://zh.wikipedia.org/wiki/%E5%AD%97%E8%8A%82%E5%BA%8F)，比對的時候要倒過來看 ## 使用MQTT查看傳輸到Server的資料 1. 請先安裝 [MQTT BOX](https://www.microsoft.com/zh-tw/p/mqttbox/9nblggh55jzg?activetab=pivot:overviewtab) 2. 新增 MQTT Client ![](https://i.imgur.com/TkaruZV.png) 3. 輸入 MQTT server 資訊 ![](https://i.imgur.com/WYFFKcx.png) * MQTT Client Name : `隨便取` * Protocol : `mqtts/tls` * Username : `engineer` * Host : `mqtt.hscc.csie.ncu.edu.tw:1883` * SSL/TLS Certificate Type : `CA signed server ceritificate` * Password : `nculoraserver` 4. 新增 Subscriber，並按下subscribe ![](https://i.imgur.com/tLToON5.png) * 主要格式為`application/[applicationID]/device/[devEUI]/rx` * applicationID : 3 * devEUI : 就是分配到的EUI * rx : server端收到的 5. 送出訊息後查看，`data`使用base64加密，所以要查看原始資料需要用base64解密 ![](https://i.imgur.com/229s4g4.png) 6. [base64解密](https://www.base64decode.org/) ![](https://i.imgur.com/amPBVso.png)