Connecting to The Things Network Using OpenMV

This tutorial explains how to connect your Portenta H7 to The Things Network (TTN) using the Vision Shield's LoRa® Connectivity feature.

Overview

This tutorial explains how to connect your Portenta H7 to The Things Network (TTN) using the Vision Shield's LoRa® Connectivity feature. A data communication channel will be enabled between the H7 and a TTN application that will be configured on your TTN console.

In order to connect your Portenta to the TTN make sure you are within the range (max. 10 Km) from an available LoRa® Gateway. Indoor gateways will have a much shorter range. It is recommended that you check LoRa® Gateway availability on The Things Network map before you try this tutorial.

You Will Learn

  • About LoRaWAN® and The Things Network,
  • About creating a TTN application,
  • How to establish a connection between the H7 and the TTN,

Required Hardware and Software

Instructions

The Portenta Vision Shield - LoRa® can be connected to the TTN and can transmit data to other devices connected to this network through a secure channel. This channel is nothing but an application on the TTN network dedicated for your board. In this tutorial, you will be guided through a step-by-step process of setting up your Portenta board and the Vision Shield - LoRa® to communicate with a TTN application using OpenMV and MicroPython. As stated before, to be able to follow this guide, to be under coverage of one of the TTN gateways. You can check for the coverage now if you have not done so yet.

1. Setting up the Environment

Start by going here. First choose your region. Next, sign in with your The Things Network account, or create a new one on the login page.

The Things Network homepage
The Things Network homepage

2. Creating an App on TTN

Once you have created an account with TTN, you need to create a TTN application. An application provides a way to aggregate data from different devices, and then use these data with other 3rd party integrations. After signing in, click on Create an application, or Go to applications if you already have one created.

Select Create an application
Select Create an application

Here you'll have a list of all your applications. Now create your first app by pressing the Create an application button.

You have now to fill only the first two fields:

  • The first one is the Owner of your app, it will automatically have you as the owner.
  • The second one is the ID of your app: this must be lowercase and without spaces.

Adding a application
Adding a application

After completing these two fields, press the "Create application" button located at the bottom left corner of the page. The dashboard will then show you an overview of the newly created app.

Adding the App Parameters
Adding the App Parameters

Let's take a closer look at these sections:

  • Application Overview: in order to use this app, you'll need the Application ID and a device specific AppKey. An EUI is a globally unique identifier for networks, gateways applications and devices. The EUIs are used to identify all parts of the LoRaWAN® inside the backend server.
  • End devices: here you can see and manage all the associated devices (e.g. your Portenta H7 with Vision Shield LoRa, Arduino MKR WAN 1300 or MKR WAN 1310), or proceed with the registration of a new one. Registering a new device lets you generate an AppEUI and an AppKey.
  • Collaborators: here you can see and manage all the app collaborators. To integrate with other collaborative platforms or to manage access rights to the app with other TTN registered profiles.
  • API keys: here you can create an API key, it's the most sensible information. It is basically the key to gain access to your app, so keep it safe.

3. Updating the Modems Firmware

To be able to use the LoRa® functionality, we need to first update the modems firmware through the Arduino IDE. Connect the Portenta and Vision shield to your computer and open the Arduino IDE. The LoRa® module on the Vision Shield can be accessed by using the MKRWAN library(if you can't find it in your examples list, you can go to tools > library manager and type "MKRWAN library" to install it). This library provides all the APIS to communicate with LoRa® and LoRaWAN® networks and can be installed from the library manager. Select the Portenta H7 (M7 core) board in the Arduino IDE, like shown below.

Select the Arduino Portenta H7 (M7 core) in the board selector.
Select the Arduino Portenta H7 (M7 core) in the board selector.

The code you need to upload and run is from the MKRWAN library, and its name is MKRWANFWUpdate_standalone. With the Portenta M7 selected, upload the MKRWANFWUpdate_standalone sketch.

Upload code to IDE
Upload code to IDE

After uploading the sketch, open the serial monitor to confirm that the firmware has been updated. If the upload was successful it will print the progress in the serial monitor.

Arduino IDE serial monitor after firmware update
Arduino IDE serial monitor after firmware update

If it all went correctly, you should see the same text in your serial monitor as on the image above.

4. Configuring the Vision Shield

It's now time to connect your Portenta H7 and LoRa® Vision Shield to TTN. You'll need to upload code to the board using OpenMV

Plug the Portenta Vision Shield - LoRa® to the Portenta H7 and them to your PC through the USB port. If the Portenta board does not show up on OpenMV, try double-pressing the reset button on the Portenta. And now update to the latest firmware in OpenMV.

The only line you may need to change before uploading the code is the one that sets the frequency. Set the frequency code according to your country if needed. You can find more information about frequency by country at this TTN link.

Consider that in Australia the boards connect correctly to TTN gateways on AS923 frequencies; AU915 frequencies requires the selection of sub band 2 which is not yet implemented in the firmware.

// change this to your regional band (eg. US915, AS923, ...) lora = Lora(band=BAND_EU868, poll_ms=60000, debug=False)

The lora.join_OTAA() or lora.join_ABP() functions connect your vision shield to the things network (TTN), using either Over-The-Air-Activation (OTAA) or Activating-By-Personalization (ABP) protocols. We just need to enter our appEui and appKey. The timeout decides how long the board will try and connect before stopping.

try: lora.join_OTAA(appEui, appKey, timeout=20000) # Or ABP: #lora.join_ABP(devAddr, nwkSKey, appSKey, timeout=5000)

We can then send data to our TTN application with lora.send_data(), in here we can decide what data we want to send to our TTN application.

try: if lora.send_data("HeLoRA world!", True): print("Message confirmed.") else: print("Message wasn't confirmed")

Now we need to read the downlink message. Using the lora.available() function we check if there is data received on the board. If there is data on the board that has been received, we can use the lora.receive_data() function to take that data and put it into a local variable. Making it easier to print in the OpenMV IDE serial terminal. Using lora.poll() we can make sure that the LoRa® module is ready before we run the loop again.

# Read downlink messages while (True): if (lora.available()): data = lora.receive_data() if data: print("Port: " + data["port"]) print("Data: " + data["data"]) lora.poll() sleep_ms(1000)

Hint: The Complete Sketch can be found in the Conclusions

Then, once the upload is completed open the Serial Terminal where you can now see firmware info, device EUI, data rate and join status.

In order to select the way in which the board is going to connect with TTN (OTAA or ABP) we need to configure it on the TTN portal. We will see which option we should select in the following steps.

5. Registering the Portenta on TTN

Before your Portenta H7 can start communicating with the TTN you need to register the board with an application. Go back to the TTN portal and scroll to End devices section on your Application dashboard, then click Add end device.

Registering a Device
Registering a Device

On the registration page, first we have to fill in information about our board. Select brand Arduino SA, and Portenta Vision Shield - LoRa® as the model. Hardware and firmware versions will automatically be set the newest ones. Then set your preferred region.

First step of registering device
First step of registering device

In the second step of registering the device, fill in End device ID and EUI. You can click the generate button next to the AppKey field to generate an app key for this device. Similarly, you can press the button next to the AppEUI field to make it all zeros, or enter your own AppEUI.

Note: The Device ID must be lowercase and without spaces. The DevEUI can be copied from the terminal in OpenMV. You can run the following script to obtain it.

from lora import * print("Device EUI:", Lora().get_device_eui())

Second step of registering device
Second step of registering device

After pressing the Register button, your board will show up on the Device Overview page. You can now see all the information needed to complete the Arduino setup.

The Things Network Device Overview
The Things Network Device Overview

6. Connecting to TTN

Once your board has been registered you can send information to TTN. Let's go back to the sketch to fill in the appEui and appKey. The sketch we use here will use OTA connection.

You can read more into OTA vs ABP activation mode at this link

Once your board has been registered you can send information to TTN. Let's proceed in OpenMV. In the sketch the application EUI and the app key needs to be filled in. Find the EUI and the App key from TTN Device Overview page.

If this process is done successfully, you will see this message:

Message confirmed.

Conclusion

If you receive this message, you have managed to configure the Portenta H7 and the Vision Shield - LoRa® on the TTN. We have retrieved the device EUI, used it to register the device in the TTN console, and programmed the board using the data provided by TTN. Now, we can send data over the LoRa® network which can be viewed from anywhere in the world (as long as we have an Internet connection and our device is in range from a TTN gateway).

Complete Sketch

from lora import * lora = Lora(band=BAND_EU868, poll_ms=60000, debug=False) print("Firmware:", lora.get_fw_version()) print("Device EUI:", lora.get_device_eui()) print("Data Rate:", lora.get_datarate()) print("Join Status:", lora.get_join_status()) appEui = "" # Add your App EUI here appKey = "" # Add your App Key here try: lora.join_OTAA(appEui, appKey, timeout=20000) # Or ABP: #lora.join_ABP(devAddr, nwkSKey, appSKey, timeout=5000) # You can catch individual errors like timeout, rx etc... except LoraErrorTimeout as e: print("Something went wrong; are you indoor? Move near a window and retry") print("ErrorTimeout:", e) except LoraErrorParam as e: print("ErrorParam:", e) print("Connected.") lora.set_port(3) try: if lora.send_data("HeLoRA world!", True): print("Message confirmed.") else: print("Message wasn't confirmed") except LoraErrorTimeout as e: print("ErrorTimeout:", e) # Read downlink messages while (True): if (lora.available()): data = lora.receive_data() if data: print("Port: " + data["port"]) print("Data: " + data["data"]) lora.poll() sleep_ms(1000)

Next Steps

  • Experiment your Vision Shield's capabilities with OpenMV and the examples from the dedicated library for Arduino. You can continue with this tutorial from the Arduino Pro site.
  • Combine LoRaWAN® protocol with an OpenMV example to develop your own IoT application. Take advantage of the Vision Shield's camera to detect, filter, classify images, read QR codes or more.

Troubleshooting

The most common issue is that the device cannot connect to a TTN gateway. Again, it is a good idea to check if we have coverage in the area we are conducting this tutorial, by checking out this map.

If we are within good range of a gateway, we should also try to move our device and antenna to a window, and even hold it out the window and move it around. This has proven successful on numerous accounts, as the signal can travel less obstructed.

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