Wireless field gateway Netduino client V1

This client is a Netduino V2Plus/V3 Ethernet/V3 Wifi device with a Silicon Labs SI7005 temperature & humidity sensor. These devices when used as sensor nodes can be battery powered and I use the Mac Address as the unique device identifier.

Reducing the power consumption, improving reliability etc. will be covered in future posts

//---------------------------------------------------------------------------------
// Copyright (c) 2017, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//---------------------------------------------------------------------------------
using System;
using System.Net;
using System.Text;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Microsoft.SPOT.Net.NetworkInformation;
using devMobile.NetMF.Sensor;
using Gralin.NETMF.Nordic;
using SecretLabs.NETMF.Hardware.Netduino;

namespace devMobile.IoT.FIeldGateway.Netduino.Client
{
   class Client
   {
      private const byte nRF24Channel = 10;
      private const NRFDataRate nRF24DataRate = NRFDataRate.DR250kbps;
      private readonly byte[] nRF24ClientAddress = Encoding.UTF8.GetBytes("TandH");
      private readonly byte[] nRF24BaseStationAddress = Encoding.UTF8.GetBytes("Base1");
      private static byte[] deviceIdentifier;
      private readonly OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
      private readonly NRF24L01Plus radio;
      private readonly SiliconLabsSI7005 sensor = new SiliconLabsSI7005();

      public Client()
      {
         radio = new NRF24L01Plus();
      }

      public void Run()
      {
         // Configure the nRF24 hardware
         radio.OnDataReceived += OnReceive;
         radio.OnTransmitFailed += OnSendFailure;
         radio.OnTransmitSuccess += OnSendSuccess;

         radio.Initialize(SPI.SPI_module.SPI1, Pins.GPIO_PIN_D7, Pins.GPIO_PIN_D3, Pins.GPIO_PIN_D2);
         radio.Configure(nRF24ClientAddress, nRF24Channel, nRF24DataRate);
         radio.Enable();

         // Setup the device unique identifer, in this case the hardware MacAddress
         deviceIdentifier = NetworkInterface.GetAllNetworkInterfaces()[0].PhysicalAddress;
         Debug.Print(" Device Identifier : " + BytesToHexString(deviceIdentifier));

         Timer humidityAndtemperatureUpdates = new Timer(HumidityAndTemperatureTimerProc, null, 15000, 15000);

         Thread.Sleep(Timeout.Infinite);
      }

      private void HumidityAndTemperatureTimerProc(object state)
      {
         led.Write(true);

         double humidity = sensor.Humidity();
         double temperature = sensor.Temperature();

         Debug.Print("H:" + humidity.ToString("F1") + " T:" + temperature.ToString("F1"));
         string values = "T " + temperature.ToString("F1") + ",H " + humidity.ToString("F0");

         // Stuff the 2 byte header ( payload type & deviceIdentifierLength ) + deviceIdentifier into payload
         byte[] payload = new byte[1 + 1 + deviceIdentifier.Length + values.Length];
         payload[0] = 1;
         payload[1] = (byte)deviceIdentifier.Length;
         Array.Copy(deviceIdentifier, 0, payload, 2, deviceIdentifier.Length);

         Encoding.UTF8.GetBytes( values, 0, values.Length, payload, 8 ) ;

         radio.SendTo(nRF24BaseStationAddress, payload );
      }

      private void OnSendSuccess()
      {
         led.Write(false);

         Debug.Print("Send Success!");
      }

      private void OnSendFailure()
      {
         Debug.Print("Send failed!");
      }

      private void OnReceive(byte[] data)
      {
         led.Write(!led.Read());

         string message = new String(Encoding.UTF8.GetChars(data));

         Debug.Print("Receive " + message); ;
      }

      private static string BytesToHexString(byte[] bytes)
      {
         string hexString = string.Empty;

         // Create a character array for hexidecimal conversion.
         const string hexChars = "0123456789ABCDEF";

         // Loop through the bytes.
         for (byte b = 0; b < bytes.Length; b++)          {             if (b > 0)
               hexString += "-";

            // Grab the top 4 bits and append the hex equivalent to the return string.
            hexString += hexChars[bytes[b] >> 4];

            // Mask off the upper 4 bits to get the rest of it.
            hexString += hexChars[bytes[b] & 0x0F];
         }

         return hexString;
      }
   }

.Net Micro framework Deployment Tool output

WindowsIoTCentralNetduinoClient

Raspberry PI UWP application output

Interrupt Triggered: FallingEdge
11:40:46 Address 5C-86-4A-00-E4-1D Length 6 Payload T 25.2,H 90 Length 11
 Sensor 5C-86-4A-00-E4-1D-T Value 25.2
 Sensor 5C-86-4A-00-E4-1D-H Value 90
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
11:41:01 Address 5C-86-4A-00-E4-1D Length 6 Payload T 25.3,H 91 Length 11
 Sensor 5C-86-4A-00-E4-1D-T Value 25.3
 Sensor 5C-86-4A-00-E4-1D-H Value 91
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
11:41:16 Address 5C-86-4A-00-E4-1D Length 6 Payload T 25.3,H 90 Length 11
 Sensor 5C-86-4A-00-E4-1D-T Value 25.3
 Sensor 5C-86-4A-00-E4-1D-H Value 90
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
11:41:31 Address 5C-86-4A-00-E4-1D Length 6 Payload T 25.3,H 90 Length 11
 Sensor 5C-86-4A-00-E4-1D-T Value 25.3
 Sensor 5C-86-4A-00-E4-1D-H Value 90
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
11:41:46 Address 5C-86-4A-00-E4-1D Length 6 Payload T 25.3,H 90 Length 11
 Sensor 5C-86-4A-00-E4-1D-T Value 25.3
 Sensor 5C-86-4A-00-E4-1D-H Value 90
Interrupt Triggered: RisingEdge

Bill of materials (prices as at Jan 2018)

Wireless field gateway devDuino client V1

This client is a devDuino V2.2 device with an AdaFruit AM2315 temperature & humidity sensor. This sensor is powered by two AAA batteries and has an on-board support for unique device identification and encryption.

In this first iteration the focus was accessing the SHA204A crypto and authentication chip, the AM2315 sensor and message payload assembly. Reducing the power consumption, improving reliability etc. will be covered in future posts.

/*
Copyright ® 2018 Jan devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE.

You can do what you want with this code, acknowledgment would be nice.

http://www.devmobile.co.nz

*/
#include <RF24.h>
#include <Adafruit_AM2315.h>
#include <sha204_library.h>

// nRF24L01 ISM wireless module setup
RF24 radio(7,6);
const int nRFPayloadSize = 32 ;
char payload[nRFPayloadSize] = "";
const byte FieldGatewayAddress[5] = "Base1";
const byte FieldGatewayChannel = 10 ;
const rf24_pa_dbm_e RadioPALevel = RF24_PA_MAX;
const rf24_datarate_e RadioDataRate = RF24_250KBPS; 

// ATSHA204 secure authentication, validation with crypto and hashing (initially only used for unique serial number)
atsha204Class sha204(A2);
const int SerialNumberLength = 9 ;
uint8_t serialNumber[SerialNumberLength];

// AM2315 I2C Outdoors temperature and humdity sensor
Adafruit_AM2315 am2315;

const int LoopSleepDelay = 30000 ;

void setup()
{
  Serial.begin(9600);
  Serial.println("Setup called");

  // Retrieve the serial number then display it nicely
  sha204.getSerialNumber(serialNumber);

  Serial.print("SNo:");
  for (int i=0; i<SerialNumberLength; i++)
  {
    // Add a leading zero
    if ( serialNumber[i] < 16)
    {
      Serial.print("0");
    }
    Serial.print(serialNumber[i], HEX);
    Serial.print(" ");
  }
  Serial.println(); 

  // Configure the AM2315 temperature & humidity sensor
  Serial.println("AM2315 setup");
  am2315.begin();

  // Configure the nRF24 module
  Serial.println("nRF24 setup");
  radio.begin();
  radio.setPALevel(RadioPALevel);
  radio.setDataRate(RadioDataRate) ;
  radio.setChannel(FieldGatewayChannel);
  radio.enableDynamicPayloads();
  radio.openWritingPipe(FieldGatewayAddress);

  delay(1000);

  Serial.println("Setup done");
}

void loop()
{
  float temperature ;
  float humidity ;
  float batteryVoltage ;

  Serial.println("Loop called");
  memset( payload, 0, sizeof( payload));

  // prepare the payload header
  int payloadLength = 0 ;
  payload[0] = 1 ; // Sensor device unique ID header with CSV payload
  payloadLength += 1;

  // Copy the ATSHA204 device serial number into the payload
  payload[1] = SerialNumberLength ;
  payloadLength += 1;
  memcpy( &payload[payloadLength], serialNumber, SerialNumberLength);
  payloadLength += SerialNumberLength ;

  // Read the temperature, humidity & battery voltage values then display nicely
  am2315.readTemperatureAndHumidity(temperature, humidity);
  Serial.print("T:");
  Serial.print( temperature, 1 ) ;
  Serial.print( "C" ) ;

  Serial.print(" H:");
  Serial.print( humidity, 0 ) ;
  Serial.print( "%" ) ;

  batteryVoltage = readVcc() / 1000.0 ;
  Serial.print(" B:");
  Serial.print( batteryVoltage, 2 ) ;
  Serial.println( "V" ) ;

  // Copy the temperature into the payload
  payload[ payloadLength] = 'T';
  payloadLength += 1 ;
  dtostrf(temperature, 6, 1, &payload[payloadLength]);
  payloadLength += 6;
  payload[ payloadLength] = ',';
  payloadLength += 1 ;

  // Copy the humidity into the payload
  payload[ payloadLength] = 'H';
  payloadLength += 1 ;
  dtostrf(humidity, 4, 0, &payload[payloadLength]);
  payloadLength += 4;
  payload[ payloadLength] = ',';
  payloadLength += 1 ;

  // Copy the battery voltage into the payload
  payload[ payloadLength] = 'V';
  payloadLength += 1 ;

  dtostrf(batteryVoltage, 5, 2, &payload[payloadLength]);
  payloadLength += 5;

  // Powerup the nRF24 chipset then send the payload to base station
  Serial.print( "Payload length:");
  Serial.println( payloadLength );

  radio.powerUp();
  delay(500);

  Serial.println( "nRF24 write" ) ;
  boolean result = radio.write(payload, payloadLength);
  if (result)
    Serial.println("Write Ok...");
  else
    Serial.println("Write failed.");

 Serial.println( "nRF24 power down" ) ;
 radio.powerDown();

 delay(LoopSleepDelay);
}

Arduino monitor output

devDuinoAM2315V1Output

Prototype hardware

devDuinoAM2315V1Bill of materials (prices as at Jan 2018)

  • devDuino V2.2 USD18
  • AdaFruit AM2315 USD30
  • Grove – 5cm buckled cable USD1.90
  • Grove – Screw Terminal USD2.90
  • 10K resistors x 2

RaspberyPI UWP application diagnostic output

Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
09:39:03 Address 01-23-32-66-C6-FE-0B-8D-EE Length 9 Payload T  25.0,H  48,V 3.31 Length 20
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-T Value 25.0
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-H Value 48
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-V Value 3.31
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
09:39:33 Address 01-23-32-66-C6-FE-0B-8D-EE Length 9 Payload T  24.9,H  48,V 3.30 Length 20
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-T Value 24.9
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-H Value 48
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-V Value 3.30
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
09:40:04 Address 01-23-32-66-C6-FE-0B-8D-EE Length 9 Payload T  24.9,H  48,V 3.31 Length 20
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-T Value 24.9
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-H Value 48
 Sensor 01-23-32-66-C6-FE-0B-8D-EE-V Value 3.31
Interrupt Triggered: RisingEdge

Wireless field gateway protocol V1

I’m going to build a number of nRF2L01P field gateways (Netduino Ethernet & Wifi running .NetMF, Raspberry PI running Windows 10 IoT Core, RedBearLab 3200  etc.), clients which run on a variety of hardware (Arduino, devDuino, Netduino, Seeeduino etc.) which, then upload data to a selection of IoT Cloud services (AdaFruit.IO, ThingSpeak, Microsoft IoT Central etc.)

The nRF24L01P is widely supported with messages up to 32 bytes long, low power consumption and 250kbps, 1Mbps and 2Mbps data rates.

The aim is to keep the protocol simple (telemetry only initially) to implement and debug as the client side code will be utilised by high school student projects.

The first byte of the message specifies the message type

0 = Echo

The message is displayed by the field gateway as text & hexadecimal.

1 = Device identifier + Comma separated values (CSV) payload

[0] – Set to 1

[1] – Device identifier length

[2]..[2+Device identifier length] – Unique device identifier bytes e.g. Mac address

[2+Device identifier length+1 ]..[31] – CSV payload e.g.  SensorID value, SensorID value

Overtime I will support more message types and wireless protocols.

 

Microsoft IoT Central dynamic payload desktop client

Unlike most of the Azure IoT Hub client examples the names and number of sensor values will only be known when messages received over the nRF24L01 wireless link are processed so the JSON message payload has to be constructed on the fly.

Using the Newtonsoft.Json NuGet package and Linq + JObject made this much easier than expected so I have added some code improve robustness.

/*

Copyright ® 2018 Jan devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE.

You can do what you want with this code, acknowledgment would be nice.

http://www.devmobile.co.nz

*/
using System;
using System.Text;
using System.Threading;
using Microsoft.Azure.Devices.Client;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace devMobile.IoT.MicrosoftIoTCentral.Desktop.DynamicPayload
{
   class Program
   {
      const string DeviceConnectionString = "YourDeviceConnectionStringFromIoTCentralGoesHere";
      const string TelemetryDataPointPropertyNameFormat = @"{0}-{1}";
      const double temperatureBase = 20.0;
      const double temperatureRange = 10.0;
      const double humidityBase = 70.0;
      const double humidityRange = 20.0;
      const double batteryVoltageBase = 3.00;
      const double batteryVoltageRange = -1.00;
      static readonly TimeSpan feedUpdateDelay = new TimeSpan(0, 0, 15);

      static void Main(string[] args)
      {
         DeviceClient Client = null;

         try
         {
            Console.WriteLine("Connecting to IoI hub");
            Client = DeviceClient.CreateFromConnectionString(DeviceConnectionString, TransportType.Amqp);
            Console.WriteLine(" Connected");
         }
         catch (Exception ex)
         {
            Console.WriteLine("Error connecting or sending data to IoT Central: {0}", ex.Message);
            return;
         }

         while (true)
         {
            // Then send simulated temperature, humidity & battery voltage data
            Random random = new Random();
            double temperature = temperatureBase + random.NextDouble() * temperatureRange;
            double humidity = humidityBase + random.NextDouble() * humidityRange;
            double batteryVoltage = batteryVoltageBase + random.NextDouble() * batteryVoltageRange;

            Console.WriteLine("Temperature {0}°C  Humidity {1}% Battery Voltage {2}V", temperature.ToString("F1"), humidity.ToString("F0"), batteryVoltage.ToString("F2"));

            // Populate the data point -
            JObject telemetryDataPoint = new JObject(); // This could be simplified but for field gateway will use this style

            string sensorDeviceSerialNumber = "0123456789ABCDEF"; // intentionally created and initialised at this level as sensor device will send over NRF24 link

            telemetryDataPoint.Add(string.Format(TelemetryDataPointPropertyNameFormat, sensorDeviceSerialNumber, "T"), temperature.ToString("F1"));
            telemetryDataPoint.Add(string.Format(TelemetryDataPointPropertyNameFormat, sensorDeviceSerialNumber, "H"), humidity.ToString("F0"));
            telemetryDataPoint.Add(string.Format(TelemetryDataPointPropertyNameFormat, sensorDeviceSerialNumber, "V"), batteryVoltage.ToString("F2"));

            string messageString = JsonConvert.SerializeObject(telemetryDataPoint);

            Console.WriteLine("{0:hh:mm:ss} > Sending telemetry: {1}", DateTime.Now, messageString);

            try
            {
               using (Message message = new Message(Encoding.ASCII.GetBytes(messageString)))
               {
                  Client.SendEventAsync(message).Wait();
                  Console.WriteLine(" Sent");
               }
            }
            catch (Exception ex)
            {
               Console.WriteLine("Error sending data to IoT Central: {0}", ex.Message);
            }

            Thread.Sleep(feedUpdateDelay);
         }
      }
   }
}

The application produces very similar output to the basic desktop client

IoTCentralDashboardDynamicPayloadClient

Microsoft IoT Central basic desktop client

One of the replacement Internet of Things services which looked worth evaluating was Microsoft’s IoT Central. My first project was to build the simplest possible desktop client (.Net Core) which simulates a limited number of sensors (sensor names, value formats etc. configured in code) and only sends data to the cloud (no device management, control or provisioning capabilities).

The only required dependencies are the Newtonsoft.Json &  Microsoft.Azure.DevicesClient NuGet packages

/*

Copyright ® 2018 Jan devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE
You can do what you want with this code, acknowledgement would be nice.
http://www.devmobile.co.nz

*/
using System;
using System.Text;
using System.Threading;
using Microsoft.Azure.Devices.Client;
using Newtonsoft.Json;

namespace devMobile.IoT.MicrosoftIoTCentral.Desktop.Basic
{
 class Program
 {
 private const string DeviceConnectionString = "YourDeviceConnectionStringFromIoTCentralGoesHere";
 const double temperatureBase = 20.0;
 const double temperatureRange = 10.0;
 const double humidityBase = 70.0;
 const double humidityRange = 20.0;
 const double batteryVoltageBase = 3.00;
 const double batteryVoltageRange = -1.00;
 static readonly TimeSpan feedUpdateDelay = new TimeSpan(0, 0, 15);

private class TelemetryDataPoint
 {
 [JsonProperty(PropertyName = "H")]
 public double Humidity { get; set; }
 [JsonProperty(PropertyName = "T")]
 public double Temperature { get; set; }
 [JsonProperty(PropertyName = "B")]
 public double BatteryVoltage { get; set; }
 }

static void Main(string[] args)
 {
 DeviceClient Client ;
 Random random = new Random();

try
 {
 Console.WriteLine("Connecting to IoI hub");
 Client = DeviceClient.CreateFromConnectionString(DeviceConnectionString, TransportType.Mqtt);

while (true)
 {
 double temperature = temperatureBase + random.NextDouble() * temperatureRange;
 double humidity = humidityBase + random.NextDouble() * humidityRange;
 double batteryVoltage = batteryVoltageBase + random.NextDouble() * batteryVoltageRange;

Console.WriteLine("Temperature {0}°C Humidity {1}% Battery Voltage {2}V", temperature.ToString("F1"), humidity.ToString("F0"), batteryVoltage.ToString("F2"));

// Populate the data point - this has a static structure and name which could be a problem for field gateway
 TelemetryDataPoint telemetryDataPoint = new TelemetryDataPoint()
 {
 BatteryVoltage = Math.Round(batteryVoltage, 2),
 Humidity = Math.Round(humidity, 0),
 Temperature = Math.Round( temperature, 1 )
 };

string messageString = JsonConvert.SerializeObject(telemetryDataPoint);
 Message message = new Message(Encoding.ASCII.GetBytes(messageString));

Console.WriteLine("{0:hh:mm:ss} > Sending telemetry: {1}", DateTime.Now, messageString);
 Client.SendEventAsync(message).Wait();
 Console.WriteLine(" Done");

Thread.Sleep(feedUpdateDelay);
 }
 }
 catch (Exception ex)
 {
 Console.WriteLine("Error connecting or sending data to IoT Central: {0}", ex.Message);
 Console.WriteLine("Press <ENTER> to exit");
 Console.ReadLine();
 }
 }
 }
}

I manually provisioned the device by copying the device connection string in the IoT Central dashboard

IoTCentralDashboardBasicClient

DesktopClientSimple

Simple dotNet Core 2 IoTCentral Client

A functional client in less than 100 lines of code with support for individual device configuration. For my FieldGateway I’m going to need more flexibility in the construction of telemetry payloads, device provisioning and configuration support.

AdaFruit IO Swagger based desktop HTTP client

Manually building clients for complex RESTful APIs (like AdaFruit.IO) can be a bit tedious so I figured I would try generating a C# http client from the Swagger OpenAPI specification(OAS) metadata.

My initial attempts using the Swagger Editor and NSwag on the AdaFruit.IO public API description didn’t go so well. (for more info see this AdaFruit.IO support forum thread) You may need to manually modify the type of the id field in Data & DataResponse, plus possibly other responses.

After figuring out how to set the API key, my code which uploads simulates three individual feeds and one feed group appears to work reliably.

/*

Copyright ® 2018 Jan devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE.

http://www.devmobile.co.nz

 */
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using AdaFruit.IO;

namespace AdaFruit.IO
{
   public partial class Client
   {
      string adaFruitIOApiKey = "yourAPIKey";

      partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, string url)
      {
         client.DefaultRequestHeaders.Add("X-AIO-Key", adaFruitIOApiKey);
      }
   }
}

namespace devMobile.IoT.Adafruit.IO.Desktop
{
   class Program
   {
      static void Main(string[] args)
      {
         string userName = "YourUserName"; // This is mixed case & case sensitive
         // The feed group and feed key are forced to lower case by UI
         const string feedGroup = "devduinov2-dot-2";
         const string temperatureKey = "t";
         const double temperatureBase = 20.0;
         const double temperatureRange = 10.0;
         const string humidityKey = "h";
         const double humidityBase = 70.0;
         const double humidityRange = 20.0;
         const string batteryVoltageKey = "v";
         const double batteryVoltageBase = 3.00;
         const double batteryVoltageRange = -1.00;
         TimeSpan feedUpdateDelay = new TimeSpan(0, 0, 15);
         TimeSpan groupUpdateDelay = new TimeSpan(0, 0, 30);
         Random random = new Random();

         while (true)
         {
            Client client = new Client();
            double temperature = temperatureBase + random.NextDouble() * temperatureRange;
            double humidity = humidityBase + random.NextDouble() * humidityRange;
            double batteryVoltage = batteryVoltageBase + random.NextDouble() * batteryVoltageRange;

            Debug.WriteLine("Temperature {0}°C  Humidity {1}%  Battery Voltage {2}V", temperature.ToString("F1"), humidity.ToString("F0"), batteryVoltage.ToString("F2"));

            // First Update the 3 feeds individually
            // Temperature
            Datum temperatureDatum = new Datum()
            {
               Value = temperature.ToString("F1"),
            };
            client.CreateDataAsync(userName, temperatureKey, temperatureDatum).Wait();
            Task.Delay(feedUpdateDelay).Wait();

            // Humidity
            Datum humidityDatum = new Datum()
            {
               Value = humidity.ToString("F0"),
            };
            client.CreateDataAsync(userName, humidityKey, humidityDatum).Wait();
            Task.Delay(feedUpdateDelay).Wait();

            // Battery
            Datum batteryDatum = new Datum()
            {
               Value = batteryVoltage.ToString("F2"),
            };
            client.CreateDataAsync(userName, batteryVoltageKey, batteryDatum).Wait();
            Task.Delay(feedUpdateDelay).Wait();

            // Then update a feed in a group
            Group_feed_data devDuinoData = new Group_feed_data();

            devDuinoData.Feeds.Add(new Anonymous2() { Key = temperatureKey, Value = temperature.ToString("F1")});
            devDuinoData.Feeds.Add(new Anonymous2() { Key = humidityKey, Value = humidity.ToString("F0")});
            devDuinoData.Feeds.Add(new Anonymous2() { Key = batteryVoltageKey, Value = batteryVoltage.ToString("F2")});

            client.CreateGroupDataAsync(userName, feedGroup, devDuinoData).Wait();
            Task.Delay(groupUpdateDelay).Wait();
         }
      }
   }
}

AdaFruit IO basic Netduino HTTP client

I use Netduino devices for teaching and my students often build projects which need a cloud based service like AdaFruit.IO to capture, store and display their sensor data.

My Proof of Concept (PoC) which uses a slightly modified version of the AdaFruit.IO basic desktop HTTP client code has been running on several Netduino 2 Plus, Netduino 3 Ethernet and Netduino 3 Wifi devices for the last couple of days and looks pretty robust.

The Netduino 3 Wifi device also supports https for improved security and privacy. They also make great field gateways as they can run off solar/battery power.

N2PN3WDashBoard

The devices have been uploading temperature and humidity measurements from a Silicon labs Si7005 sensor. (Outside sensor suffering from sunstrike)

N3WifiTemperatureAndHumiditySensor

program.cs

*

Copyright ® 2017 December devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE.

http://www.devmobile.co.nz

*/
using System;
using System.Net;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Microsoft.SPOT.Net.NetworkInformation;
using SecretLabs.NETMF.Hardware.Netduino;
using devMobile.NetMF.Sensor;
using devMobile.IoT.NetMF;

namespace devMobile.IoT.AdaFruitIO.NetMF.Client
{
   public class Program
   {
      private const string adaFruitIOApiBaseUrl = @"https://IO.adafruit.com/api/v2/";
      private const string group = "netduino3";
      private const string temperatureFeedKey = "t";
      private const string humidityFeedKey = "h";
      private const string adaFruitUserName = "YourUserName";
      private const string adaFruitIOApiKey = "YourAPIKey";
      private static readonly TimeSpan timerDueAfter = new TimeSpan(0, 0, 15);
      private static readonly TimeSpan timerPeriod = new TimeSpan(0, 0, 30);
      private static OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
      private static SiliconLabsSI7005 sensor = new SiliconLabsSI7005();
      private static AdaFruitIoClient adaFruitIoClient = new AdaFruitIoClient(adaFruitUserName, adaFruitIOApiKey, adaFruitIOApiBaseUrl);

      public static void Main()
      {
         // Wait for Network address if DHCP
         NetworkInterface networkInterface = NetworkInterface.GetAllNetworkInterfaces()[0];
         if (networkInterface.IsDhcpEnabled)
         {
            Debug.Print(" Waiting for DHCP IP address");

            while (NetworkInterface.GetAllNetworkInterfaces()[0].IPAddress == IPAddress.Any.ToString())
            {
               Debug.Print(" .");
               led.Write(!led.Read());
               Thread.Sleep(250);
            }
            led.Write(false);
         }

         // Display network config for debugging
         Debug.Print("Network configuration");
         Debug.Print(" Network interface type : " + networkInterface.NetworkInterfaceType.ToString());
         Debug.Print(" MAC Address : " + BytesToHexString(networkInterface.PhysicalAddress));
         Debug.Print(" DHCP enabled : " + networkInterface.IsDhcpEnabled.ToString());
         Debug.Print(" Dynamic DNS enabled : " + networkInterface.IsDynamicDnsEnabled.ToString());
         Debug.Print(" IP Address : " + networkInterface.IPAddress.ToString());
         Debug.Print(" Subnet Mask : " + networkInterface.SubnetMask.ToString());
         Debug.Print(" Gateway : " + networkInterface.GatewayAddress.ToString());

         foreach (string dnsAddress in networkInterface.DnsAddresses)
         {
            Debug.Print(" DNS Server : " + dnsAddress.ToString());
         }

         Timer humidityAndtemperatureUpdates = new Timer(HumidityAndTemperatureTimerProc, null, timerDueAfter, timerPeriod);

         Thread.Sleep(Timeout.Infinite);
      }

      static private void HumidityAndTemperatureTimerProc(object state)
      {
         led.Write(true);

         try
         {
            double humidity = sensor.Humidity();

            Debug.Print(" Humidity " + humidity.ToString("F0") + "%");
            adaFruitIoClient.FeedUpdate(group, humidityFeedKey, humidity.ToString("F0"));
         }
         catch (Exception ex)
         {
            Debug.Print("Humidifty read+update failed " + ex.Message);

            return;
         }

         try
         {
            double temperature = sensor.Temperature();

            Debug.Print(" Temperature " + temperature.ToString("F1") + "°C");
            adaFruitIoClient.FeedUpdate(group, temperatureFeedKey, temperature.ToString("F1"));
         }
         catch (Exception ex)
         {
            Debug.Print("Temperature read+update failed " + ex.Message);

            return;
         }

         led.Write(false);
      }

      private static string BytesToHexString(byte[] bytes)
      {
         string hexString = string.Empty;

         // Create a character array for hexidecimal conversion.
         const string hexChars = "0123456789ABCDEF";

         // Loop through the bytes.
         for (byte b = 0; b < bytes.Length; b++)          {             if (b > 0)
               hexString += "-";

            // Grab the top 4 bits and append the hex equivalent to the return string.
            hexString += hexChars[bytes[b] >> 4];

            // Mask off the upper 4 bits to get the rest of it.
            hexString += hexChars[bytes[b] & 0x0F];
         }

         return hexString;
      }
   }
}

AdaFruit.IO client.cs, handles feed groups and individual feeds

/*

Copyright ® 2017 December devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE.

http://www.devmobile.co.nz

*/
using System;
using System.IO;
using System.Net;
using System.Text;
using Microsoft.SPOT;

namespace devMobile.IoT.NetMF
{
   public class AdaFruitIoClient
   {
      private const string apiBaseUrlDefault = @"http://IO.adafruit.com/api/v2/";
      private string apiBaseUrl = "";
      private string userName = "";
      private string apiKey = "";
      private int httpRequestTimeoutmSec;
      private int httpRequestReadWriteTimeoutmSec;

      public AdaFruitIoClient(string userName, string apiKey, string apiBaseUrl = apiBaseUrlDefault, int httpRequestTimeoutmSec = 2500, int httpRequestReadWriteTimeoutmSec = 5000)
      {
         this.apiBaseUrl = apiBaseUrl;
         this.userName = userName;
         this.apiKey = apiKey;
         this.httpRequestReadWriteTimeoutmSec = httpRequestReadWriteTimeoutmSec;
         this.httpRequestTimeoutmSec = httpRequestTimeoutmSec;
      }

      public void FeedUpdate(string group, string feedKey, string value)
      {
         string feedUrl;

         if (group.Trim() == string.Empty)
         {
            feedUrl = apiBaseUrl + userName + @"/feeds/" + feedKey + @"/data";
         }
         else
         {
            feedUrl = apiBaseUrl + userName + @"/feeds/" + group.Trim() + "." + feedKey + @"/data";
         }

         HttpWebRequest request = (HttpWebRequest)WebRequest.Create(feedUrl);
         {
            string payload = @"{""value"": """ + value + @"""}";
            byte[] buffer = Encoding.UTF8.GetBytes(payload);

            DateTime httpRequestedStartedAtUtc = DateTime.UtcNow;

            request.Method = "POST";
            request.ContentLength = buffer.Length;
            request.ContentType = @"application/json";
            request.Headers.Add("X-AIO-Key", apiKey);
            request.KeepAlive = false;
            request.Timeout = this.httpRequestTimeoutmSec;
            request.ReadWriteTimeout = this.httpRequestReadWriteTimeoutmSec;

            using (Stream stream = request.GetRequestStream())
            {
               stream.Write(buffer, 0, buffer.Length);
            }

            using (var response = (HttpWebResponse)request.GetResponse())
            {
               Debug.Print(" Status: " + response.StatusCode + " : " + response.StatusDescription);
            }

            TimeSpan duration = DateTime.UtcNow - httpRequestedStartedAtUtc;
            Debug.Print(" Duration: " + duration.ToString());
         }
      }
   }
}

Bill of materials for PoC