This repo provides a basic demonstration of a sample weather monitor application. It makes use of an 8x8 matrix display to periodically present the local weather conditions, which are retrieved from the OpenWeather API. The OpenWeather data is parsed using cJSON.

The application is based on the FreeRTOS real-time operating system and which will run on the “non-secure” side of Microvisor. FreeRTOS is included as a submodule.

The ARM CMSIS-RTOS API is used an an intermediary between the application and FreeRTOS to make it easier to swap out the RTOS layer for another should you wish to do so.

The application code files can be found in the App/ directory. The ST_Code/ directory contains required components that are not part of the icrovisor STM32U5 HAL, which this sample code accesses as a submodule. The required FreeRTOSConfig.h and stm32u5xx_hal_conf.h configuration files are located in the config/ directory.

This repo makes uses of git submodules, some of which are nested within other submodules. To clone the repo, run:

git clone https://github.com/korewireless/Microvisor-Demo-Weather-Device.git

and then:

cd Microvisor-Demo-Weather-Device
git submodule update --init --recursive

When the repo is updated, and you pull the changes, you should also always update dependency submodules. To do so, run:

git submodule update --remote --recursive

We recommend following this by deleting your build directory.

You will need a Twilio account. Sign up now if you don’t have one.

The demo makes use of the OpenWeather OneCall API. To make use of this API, you will need to set up an OpenWeather account and obtain an API key.

We now use OneCall 3.0. While this is free for fewer than 1000 calls per day, you will be required to provide payment details to access the API.

Get your location — or any location co-ordinates — from Google Maps.

You will also need the following hardware:

• A Microvisor Nucleo Development Board. You will need to solder male header pins to the two GPIO banks on the board, or at the very least to the connected pins shown in the circuit diagram below.
• An HT16K33-based 8x8 matrix display, e.g., Adafruit 1.2-inch 8x8 LED Matrix and Backpack.
• Four female-to-female jumper wires.

Assemble the following circuit:

The display is shown on a breakout board which include I²C pull-up resistors. If you add the display and sensor as raw components, you will need to add pull-ups on the I²C SDA and SCL lines. You only need a single pull-up on each line.

This project is written in C. At this time, we only support Ubuntu 20.0.4. Users of other operating systems should build the code under a virtual machine running Ubuntu, or with Docker.

Note Users of unsupported platforms may attempt to install the Microvisor toolchain using this guidance.

If you are running on an architecture other than x86/amd64 (such as a Mac with Apple silicon), you will need to override the platform when running docker. This is needed for the Twilio CLI apt package which is x86 only at this time:

export DOCKER_DEFAULT_PLATFORM=linux/amd64

Build the image:

docker build --build-arg UID=$(id -u) --build-arg GID=$(id -g) -t mv-weather-demo-image .

Run the build:

docker run -it --rm -v $(pwd)/:/home/mvisor/project/ \
  --env-file env.list \
  --name mv-weather-demo mv-weather-demo-image

Note You will need to have exported certain environment variables, as detailed below.

Under Docker, the demo is compiled, uploaded and deployed to your development board. It also initiates logging — hit ctrl-c to break out to the command prompt.

Under Ubuntu, run the following:

sudo apt install gcc-arm-none-eabi binutils-arm-none-eabi \
  git curl build-essential cmake libsecret-1-dev jq openssl

Install the Twilio CLI. This is required to view streamed logs and for remote debugging. You need version 4.0.1 or above.

Note If you have already installed the Twilio CLI using npm, we recommend removing it and then reinstalling as outlined below. Remove the old version with npm remove -g twilio-cli.

wget -qO- https://twilio-cli-prod.s3.amazonaws.com/twilio_pub.asc | sudo apt-key add -
sudo touch /etc/apt/sources.list.d/twilio.list
echo 'deb https://twilio-cli-prod.s3.amazonaws.com/apt/ /' | sudo tee /etc/apt/sources.list.d/twilio.list
sudo apt update
sudo apt install -y twilio

Close your terminal window or tab, and open a new one. Now run:

twilio plugins:install @twilio/plugin-microvisor

Running the Twilio CLI and the Microvisor Plugin to upload the built code to the Microvisor cloud for subsequent deployment to your Microvisor Nucleo Board uses the following Twilio credentials stored as environment variables. They should be added to your shell profile:

export TWILIO_ACCOUNT_SID=ACxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
export TWILIO_AUTH_TOKEN=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
export MV_DEVICE_SID=UVxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

You can get the first two from your Twilio Console account dashboard.

Enter the following command to get your target device’s SID and, if set, its unqiue name:

twilio api:microvisor:v1:devices:list

Before you build the app, set the following OpenWeather environment variables:

export MVOW_LAT=<YOUR_LATITUDE_CO-ORDINATE>
export MVOW_LNG=<YOUR_LONGITUDE_CO-ORDINATE>

We now use the Microvisor cloud’s secrets store to hold your OpenWeather API key securely so it is not baked into the app itself. Set this up this way:

Run:

twilio api:microvisor:v1:secrets:create --key secret-ow-api-key --value <YOUR_OW_API_KEY>

This will upload the API key as a key-value pair. The pair’s key is secret-ow-api-key. If you change this value, make sure to change the value of the #define API_KEY_SECRET_NAME in openweather.h.

The application uses this key to retrieve the API key from the cloud and hold it in RAM.

It is left as an exercise for the reader to update the application to load the device’s latitude and longitude using this method rather than local environment variables.

Run:

twilio microvisor:deploy . --devicesid ${MV_DEVICE_SID} --log

This will compile, bundle and upload the code, and stage it for deployment to your device. If you encounter errors, please check your stored Twilio credentials.

The --log flag initiates log-streaming.

You can start log streaming separately — for example, in a second terminal window — with this command:

twilio microvisor:deploy . --devicesid ${MV_DEVICE_SID} --log-only

For more information, run

twilio microvisor:deploy --help

You may log your application over UART on pin PD5 — pin 41 in bank CN11 on the Microvisor Nucleo Development Board. To use this mode, which is intended as an alternative to application logging, typically when a device is disconnected, connect a 3V3 FTDI USB-to-Serial adapter cable’s RX pin to PD5, and a GND pin to any Nucleo GND pin. Whether you do this or not, the application will continue to log via the Internet.

This release supports remote debugging, and builds are enabled for remote debugging automatically. Change the value of the line

set(ENABLE_REMOTE_DEBUGGING 1)

in the root CMakeLists.txt file to 0 to disable this.

Enabling remote debugging in the build does not initiate a GDB session — you will have to do this manually. Follow the instructions in the Microvisor documentation.

This repo contains a .gdbinit file which sets the remote target to localhost on port 8001 to match the Twilio CLI Microvisor plugin remote debugging defaults.

Remote debugging sessions are now encrypted. The file app/CMakeLists.txt generates new remote debugging keys at each build. These are placed in the /build/app directory, which is ignored for git commits. You will need to pass the path to the private key to the Twilio CLI Microvisor plugin to decrypt debugging data. The plugin will output this path for you.

Alternatively, generate the keys manually and pass their locations to the plugin:

twilio microvisor:deploy . --devicesid ${MV_DEVICE_SID} \
   --privatekey /path/to/existing/private/key.pem \
   --publickey /path/to/existing/public/key.pem

The sample code and Microvisor SDK is © 2024, KORE Wireless. It is licensed under the terms of the MIT License.

The SDK makes use of code © 2021, STMicroelectronics and affiliates. This code is licensed under terms described in this file.

The SDK makes use ARM CMSIS © 2004, ARM. It is licensed under the terms of the Apache 2.0 License.

FreeRTOS is © 2021, Amazon Web Services, Inc. It is licensed under the terms of the Apache 2.0 License.

cJSON is © 2009-2017 Dave Gamble and cJSON contributors. It is licensed under the terms of the MIT License.