iharosi / sensor-api

Restful Web API for Adafruit BME280

Restful Web API for Adafruit BME280

This is a Node.JS Restful Web API service for the Pressure, Temp and Humidity sensor of Adafruit BME280.

Prerequisites and preparations

Raspberry Pi Zero with Raspbian OS

1. Download Raspbian Stretch Lite and use Etcher to install the image to the SD card
2. Follow the Raspberry Pi Zero Headless Setup instruction by David Maitland to prepare the OS without any peripherals

Connect Adafruit BME280 through GPIO pins by I2C

1. Enable I2C connection with sudo raspi-config command

2. Check the Raspberry Pi Zero pinouts

3. Connect BME280 by I2C

   Signal	Raspberry Pi Zero pin	BME280 pin
   Power +5V	Pin 4	VIN pin
   Data SDA	Pin 3	SDI pin
   Clock SCL	Pin 5	SCK pin
   Ground	Pin 6	GND pin

4. Install I2C tools: sudo apt install i2c-tools

5. Check the presence of the device by running sudo i2cdetect -y 1.
   It should show address 0×77 if connection is correct.

6. Install Adafruit Python GPIO library

7. Test data reading with Adafruit Python BME280 examples

Installation

Clone this repository

1. git clone https://github.com/iharosi/sensor-api.git ~/sensor-api

Install database service and cron service

1. Install mongodb
   apt install mongodb
2. Install cron script
   To read the sensor every 10 minutes we install a cron script.
   Run crontab -e and insert the following line at the end of the file: 0,10,20,30,40,50 * * * * /usr/local/bin/node ~/sensor-api/sampling.js > /dev/null 2>&1

Install systemd sensor-api service

1. Create sensor-api service unit file at /etc/systemd/system/sensor-api.service with the following content:

   [Unit]
   Description=Sensor API
   Requires=networking.service mongodb.service
   After=networking.service mongodb.service
   
   [Service]
   WorkingDirectory=/home/pi/sensor-api
   ExecStart=/usr/local/bin/node server.js
   Restart=always
   RestartSec=10
   StandardOutput=journal
   StandardError=journal
   SyslogIdentifier=sensor-api
   User=pi
   Group=pi
   
   [Install]
   WantedBy=multi-user.target
   

2. Reload configuration files
   systemctl daemon-reload

3. Install sensor-api service
   systemctl enable sensor-api

Usage

1. Start sensor-api service
   systemctl start sensor-api
2. Check if the service has successfully started
   systemctl status sensor-api

The service will listen on port 3000.

API

Endpoint	Description
/	This page
/sensor/	List all data
/sensor/last	Get last measured data
/sensor/id/{Object ID}	Get data with the given ID