特別企画 ESP32とラズパイで作る本格IoT（Vol.77記載）

著者：魔法少女

マイコン「ESP32」と小型コンピュータ「Raspberry Pi」を使って本格的なIoT（モノのインターネット）環境を構築してみましょう。本企画では、五つの会議室の温度、湿度、利用状況を監視・分析し、会議室内の電源を制御するシステムを構築します。

シェルスクリプトマガジン Vol.77は以下のリンク先でご購入できます。

図4　ユーザー名とパスワードの生成スクリプト（user_create.sh）

#!/bin/sh

tee ~/confer_pw.txt << EOF > /dev/null
pub1:passwd1
pub2:passwd2
pub3:passwd3
pub4:passwd4
pub5:passwd5
sub1:passwd6
EOF
for i in $(seq 6)
do
sed -i -e "s|passwd${i}|$(pwgen 8 1)|" ~/confer_pw.txt
done

図5　Eclipse Mosquittoの認証設定スクリプト（mosquitto_setting.sh）

#!/bin/sh

sudo cp ~/confer_pw.txt /etc/mosquitto/confer_pwfile
sudo mosquitto_passwd -U /etc/mosquitto/confer_pwfile
sudo tee /etc/mosquitto/conf.d/confer.conf << EOF > /dev/null
listener 1883
allow_anonymous false
password_file /etc/mosquitto/confer_pwfile
EOF
sudo systemctl reload mosquitto

図7　サブスクライバのプログラム（subscriber.py)

#!/bin/env python3

import paho.mqtt.client as mqtt
import time

##
mqtt_topic = "confer/#"
csv_file = "./room1.csv"
subscriber_username = "sub1"
subscriber_password = "IBehie1h"
broker_hostname = "localhost"

##
def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))
    client.subscribe(mqtt_topic)

def on_message(client, userdata, msg):
    now_unixtime = time.time()
    iot_device = msg.topic + "," + str(msg.payload, encoding='utf-8', errors='replace') + "," + str(now_unixtime)
    print(iot_device)
    with open(csv_file, mode='a') as f:
        f.write(iot_device + "\n")

##
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.username_pw_set(username=subscriber_username, password=subscriber_password)
client.connect(broker_hostname)
client.loop_forever()

図24　ESP32搭載ボートの起動時に無線LANに接続するプログラム（boot.py）

import network

SSID = 'USP_OFFICE_B'
PASSWORD = 'uspuspusp1234'

wlan_if = network.WLAN(network.STA_IF)
wlan_if.active(True)
wlan_if.connect(SSID, PASSWORD)

図25　パブリッシャのプログラム（main.py）

import time
import dht
from machine import Pin
from umqtt.simple import MQTTClient

mqtt_topic = "confer/room1"
publisher_username = "pub1"
publisher_password = "パスワード"
publisher_id = "room1_esp32"
broker_address = "192.168.1.100"
interval_time = "1"

hf_sensor = Pin(5, Pin.IN, Pin.PULL_UP)
th_sensor = dht.DHT11(Pin(22))

time.sleep(5)

while True:
  value1 = hf_sensor.value()
  th_sensor.measure()
  value2 = th_sensor.temperature()
  value3 = th_sensor.humidity()
  iot_value = str(value1)+","+str(value2)+","+str(value3)
  print(iot_value)
  publisher = MQTTClient(publisher_id,broker_address,user=publisher_username,password=publisher_password)
  publisher.connect()
  publisher.publish(mqtt_topic, msg=iot_value)
  publisher.disconnect()
  time.sleep(int(interval_time))