Skip to content

Latest commit

 

History

History
185 lines (115 loc) · 10.7 KB

README.md

File metadata and controls

185 lines (115 loc) · 10.7 KB
Raw

Data Transport

  1. Overview
  2. Resources
  3. Connecting nRF52840 and Pi using BLE
  4. Connecting to Wi-Fi
  5. Using the ThingSpeak IoT platform
  6. Sending data to the ThingSpeak REST API
  7. Sending data to the ThingSpeak MQTT API
  8. Sending data to ThingSpeak with LoRaWAN
  9. CircuitPython examples
  10. Python examples

Overview

Data transport (data transmission, also data communication or digital communications) is the transfer of data (a digital bitstream or a digitized analog signal) over a point-to-point or point-to-multipoint communication channel.

--- from Wikipedia

To transfer the data, a communication channel must be established between the "Connected device" and a "Cloud Backend".

We will use examples of data transport technologies to find out:

  • how to establish a communication channel between two communication parties?
  • how the sensor values can be transfered to the backend?
  • how transfer protocols of the internet can be used to enable the transfer?
  • how these transfer protocols differ?

Resources

Connecting nRF52840 and Pi using BLE

Bluetooth Low Energy (BLE) is well suited to connect a microcontroller like the nRF5280 to a dedicated computer like a Raspberry Pi. In such a scenario, the Pi can act as a hub to collect data from multiple sensors all connected to one microcontroller. The Pi, which is more powerful than any microcontroller, can perform initial data processing before forwarding the processed data to a central cloud service or database.

Adafruit provides corresponding libraries and tutorials for BLE communiation:

Remark: Use BLE libraries from the same provider to easily build a BLE connection between the communication partners.

Connecting to Wi-Fi

Wi-Fi is well known. It can provide high-throughput data transfer for both enterprise and home environments. However, in the IoT space, its major limitations in coverage, scalability and power consumption make the technology much less prevalent.

Since IoT is widely diverse and multifaceted, their is no one-size-fits-all communication solution. Figure 1 shows the most important technologies in comparison with their Data Rate & Power Consumption and Range.

Figure 1: Visualization from Behr Technologies

However, Wi-Fi can be used well in prototyping. Our two hardware platforms are or can be equipped with Wi-Fi.

Using the ThingSpeak IoT platform

We will use ThingSpeak as our cloud backend. ThingSpeak is an IoT analytics platform that allows you to aggregate, visualize, and analyze live data streams in the cloud.

For an introduction look at this tutorial:

Your steps to get started with ThingSpeak are:

  1. Create a free account

    ThingSpeak does provide free access, but with limited resources and functionality. To use ThingSpeak, start creating a free account with your FHNW email address by clicking the button as shown in figure 1.

    Figure 1: Get started on ThingSpeak with a free, limited account

  2. Create a channel

    To be able to collect data on ThingSpeak, you have to provide a so-called Channel. Use the information in Collect Data in a New Channel to setup your first channel with 3 fields: Temperature, Humidity, Dew Point

    Save the channel.

  3. Get your access keys

    API keys enable you to write data to a channel or read data from a private channel. API keys are auto-generated when you create a new channel.

    You can access your API key icon your channel page in tab API Keys (see Figure 2). You will need the Write API Key

  4. Test your channel

    You can test your channel by sending test data manually using the HTTP protocol.

    Use curl to send a HTTP POST request to ThingSpeak:

    $ curl -v https://api.thingspeak.com/update -d "api_key=MY_WRITE_API_KEY&field1=5&field2=10&field3=20"

    or use your browser to send a HTTP GET request, what is also supported:

    https://api.thingspeak.com/update?api_key=MY_WRITE_API_KEY&field1=0&field2=10&field3=20

    You should see on each chart one red point, which corresponds to your test values as shown in figure 2.

    Figure 2: Charts with first test data

  5. Create idb channel

    For your CircuitPython and Python examples we need a new channel with the two fields temperature and humidity.

    Create this channel and get the API Keys.

  6. Done

    Your ThingSpeak channel is now ready to collect your sensor data.

Sending data to the ThingSpeak REST API

The Hypertext Transfer Protocol (HTTP) is an application layer protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access.

Representational state transfer (REST) is an architectural style designed as a request-response model that communicates over HTTP. The ThingSpeak IoT platform uses the REST API calls GET, POST, PUT, and DELETE to create and delete channels, read and write channel data, and clear the data in a channel. A web browser or client sends a request to the server, which responds with data in the requested format.

  • To get started with the ThingSpeak REST API, see REST API

Sending data to the ThingSpeak MQTT API

MQTT is a publish/subscribe communication protocol that uses TCP/IP sockets or WebSockets. The ThingSpeak IoT platform enables clients to update and receive updates from channel feeds via the ThingSpeak MQTT broker. A client device connects to the MQTT broker and can publish to a channel or subscribe to updates from that channel.

Sending data to Thingspeak with LoRaWAN

LoRaWAN is a high capacity, Long Range, open, Low Power Wide Area Network (LPWAN) standard designed for LoRa Powered IoT Solutions by the LoRa Alliance. It is a bi-directional protocol which takes full advantage of all the features of the LoRa technology to deliver services including reliable message delivery, end to end security, location and multicast capabilities. The standard ensures the interoperability of the various LoRaWAN networks world-wide.

TheThingsNetwork (TTN) is a community-based initiative to build a LoRaWAN for the Internet of Things.

The integration for ThingSpeak to external platforms like AWS IoT or ThingSpeak can be found on their integrations webpage.

CircuitPython examples

Try these examples with CircuitPython on the nRF52840.

Wi-Fi

Consider to setup a hotspot on your smartphone and to access and use a WLAN anywhere.

HTTP

These examples use generic HTTP servers.

These examples use the ThingSpeak REST API.

MQTT

These examples use a generic MQTT broker.

These examples use the ThingSpeak MQTT API.

LoRaWAN

Python examples

Try these examples with Python on the Raspberry Pi Zero W.

Wi-Fi

Use the information Configure Wi-Fi on the Wiki to add your Pi to your WLAN.

Note that you can add to the configuration file wpa_supplicant.conf more than one network. Consider to setup a hotspot on your smartphone and to access and use a WLAN anywhere.

Try these examples with Python on the Raspberry Pi and with Wi-Fi enabled: