Tag Archives: Visual Studio

Web service call with Azure Sphere and curl

libcurl library is included in the Azure Sphere SDK. For IoT applications web service calls are almost a pre-requisite to connect everyday objects to the Internet. Being able to invoke web service as convenient as the Azure Sphere is definitely an advantage.

Sample application is available at git hub. Open with Visual Studio the HTTPS_Curl_Easy solution. This project defaults to open example.com. To change to the web service desired, first update the app_manifest.json file for the allowed host.

"SchemaVersion": 1,
"Name": "HTTPS_Curl_Easy",
"ComponentId": "20191001-0000-0000-0000-000000000000",
"EntryPoint": "/bin/app",
"CmdArgs": [],
"Capabilities": {
"AllowedConnections": [ "example.com", "your.webserver.com" ]
"ApplicationType": "Default"

Then open the main.c file and point the Azure Sphere to the Internet.

 if ((res = curl_easy_setopt(curlHandle, CURLOPT_URL, "http://your.webserver.com/")) != CURLE_OK) {
LogCurlError("curl_easy_setopt CURLOPT_URL", res);
goto cleanupLabel;

Check the log from web server.




Road testing Azure Sphere Starter Kit with Visual Studio and Azure IoT Hub

The Avnet Azure Sphere Starter Kit is a development board featuring the Azure Sphere module with a MT3620 processor. It is designed for end-to-end IoT with security in mind, and is tightly integrated with the Azure cloud service.

To try out developing IoT solutions using this kit, Visual Studio 2017 or 2019 is required. The Azure Sphere SDK can added to Visual Studio. An Azure account is needed to create an Azure Directory user in the cloud. For details of these preparations, Microsoft provided step by step instructions.

Out of the box, the kit has to be connected to a PC with Internet access via a USB cable (one is included in the kit).  The driver should self install. Once connected, open up the Azure Sphere Developer Command Prompt. Each kit has to be registered to the Azure cloud before it can function. The following outline the basic commands to complete the registration.

azsphere login

azsphere tenant create --name sphere01-tenant

azsphere device claim

azsphere device show-ota-status

azsphere device recover

azsphere device wifi show-status

azsphere device wifi add --ssid  --key

After completed the basic registration and Wifi setup, issue the command below to ready the Azure Sphere to work with Visual Studio in debug mode.

azsphere device prep-debug

At this point, open Visual Studio, and pull a sample project from Github. For example, the demo project at https://github.com/CloudConnectKits/Azure_Sphere_SK_ADC_RTApp. Compile and debug the project.

Observe the Output window to see the data fetched from the Azure Sphere. In Sphere’s terms, this is called side-loading a program.sphere14

Once the debugger exits, the Sphere will no longer run the program. To deploy the program in a more permanent manner, use the following commands to do an Over the Air (OTA) deployment.

azsphere feed list
--> [3369f0e1-dedf-49ec-a602-2aa98669fd61] 'Retail Azure Sphere OS'
azsphere device prep-field --newdevicegroupname  --newskuname 

azsphere device link-feed --dependentfeedid 3369f0e1-dedf-49ec-a602-2aa98669fd61 --imagepath "C:\Users\dennis\source\repos\AvnetAzureSphereStarterKitReferenceDesign1\AvnetStarterKitReferenceDesign\bin\ARM\Debug\AvnetStarterKitReferenceDesign.imagepackage" --newfeedname sphere01-test-avnet --force
Adding feed with ID 'e9243998-58b1-42c5-a7a3-7d76e55e5603' to device group with ID '193d1734-f1e3-4af1-a42e-e4e0a99f585c'.
Creating new image set with name 'ImageSet-Avnet-Starter-Kit-reference-V1.-2019.09.21-12.17.22+08:00' for images with these IDs: 4ae124ed-503a-4cf2-acf9-198c3decd55d.


azsphere device image list-installed

azsphere device prep-field --devicegroupid 193d1734-f1e3-4af1-a42e-e4e0a99f585c

Exploring Theano with Keras

Theano needs no introduction in the field of deep learning. It is based on Python and supports CUDA. Keras is a libray that wraps the complexity of Theano to provide a high level abstraction for developing deep learning solutions.

Installing Theano and Keras are easy and there are tons of resources available online. However, my primary CUDA platform is on Windows so most standard guides that are based on Linux required some adaptations. Most notably are the proper setting of the PATH variable and the use of the Visual Studio command prompt.

The basic installation steps include setting up of CUDA, a scientific python environment, and then Theano and Keras. CuDNN is optional and required Compute Capability of greater than 3.0 which unfortunately my GPU is a bit old and does not meet this requirement.


Some programs on Windows platform encountered errors and found to be library related issues. Like this one that failed to compile on Spyder can be resolved using the Visual Studio Cross Tool Command Prompt.

The Nvidia profiler checking for the performance of the GPU, running the Keras example of the MNIST digits with MLP.keras2

Implementing parallel GPU function in CUDA for R

There are existing R packages for CUDA. But if there is a need to customize your own parallel code on NVIDIA GPU to be called from R, it is possible to do so with the CUDA Toolkit. This post demonstrates a sample function to approximate the value of Pi using Monte Carlo method which is accelerated by GPU. The sample is built using Visual Studio 2010 but the Toolkit is supported on linux platforms as well. It is assumed that the Visual Studio is integrated with the CUDA Toolkit.

The first thing to do is to create a New Project using the Win32 Console Application template, and specify DLL with Empty project option.


And then, some standard project environment customization including:

CUDA Build Customization:

CUDA Runtime, select Shared/dynamic CUDA runtime library:

Project Dependencies setting. Since the CUDA code in this example utilize curand for Monte Carlo, the corresponding library must be included or else the linking will fail.

Finally the time to code. Only a cu file is needed which resembles the standard directives. It is important to include the extern declaration as below for R to call.

After a successful compile, the DLL will be created with the CUDA code. This DLL will be registered in R for calling.

Finally, start R and issue the dyn.load command to load the DLL into the running environment. Shown below is a “wrapper” R function to make calling the CUDA code easier. Notice at the heart of this wrapper is the .C function.

Last but not least, the CUDA Toolkit comes with a visual profiler which is capable to be launched for profiling the performance of the NVIDIA GPU. It can be launched from the GUI, or using a command line like the example below. It should be noted that the command line profiler must be started before R or it might not be able to profile properly.RCuda11

The GUI profiler is equipped with a nice interface to show performance statistics.RCuda10