Wireless field gateway Netduino client V2

This revised 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.

In this version of the protocol the message type & device identifier are nibbles packed into the first bye of the message. This saved a byte but limits the number of message types and device identifier length

//---------------------------------------------------------------------------------
// Copyright (c) 2018, 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("T&H01");
      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 single byte header ( payload type nibble & deviceIdentifierLength nibble ) + deviceIdentifier into first byte of payload
         byte[] payload = new byte[ 1 + deviceIdentifier.Length + values.Length];
         payload[0] =  (byte)((1 << 4) | deviceIdentifier.Length );
         Array.Copy(deviceIdentifier, 0, payload, 1, deviceIdentifier.Length);

         Encoding.UTF8.GetBytes(values, 0, values.Length, payload, deviceIdentifier.Length + 1 );

         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  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;
      }
   }
}

Bill of materials (prices as at March 2018)

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

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

nRF24 Windows 10 IoT Core Background Task

First step is to build a basic Windows 10 IoT Core background task which can receive and display messages sent from a variety of devices across an nRF24L01 wireless link.

If you create a new “Windows IoT Core” “Background Application” project then copy this code into StartupTasks.cs the namespace has to be changed in the C# file, project properties\library\Default namespace and “Package.appxmanifest”\declarations\Entry Point.

/*

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.Diagnostics;
using System.Text;
using Radios.RF24;
using Windows.ApplicationModel.Background;

namespace devmobile.IoTCore.nRF24BackgroundTask
{
    public sealed class StartupTask : IBackgroundTask
    {
      private const byte ChipEnablePin = 25;
      private const byte ChipSelectPin = 0;
      private const byte nRF24InterruptPin = 17;
      private const string BaseStationAddress = "Base1";
      private const byte nRF24Channel = 10;
      private RF24 Radio = new RF24();
      private BackgroundTaskDeferral deferral;

      public void Run(IBackgroundTaskInstance taskInstance)
        {
         Radio.OnDataReceived += Radio_OnDataReceived;
         Radio.OnTransmitFailed += Radio_OnTransmitFailed;
         Radio.OnTransmitSuccess += Radio_OnTransmitSuccess;

         Radio.Initialize(ChipEnablePin, ChipSelectPin, nRF24InterruptPin);
         Radio.Address = Encoding.UTF8.GetBytes(BaseStationAddress);
         Radio.Channel = nRF24Channel;
         Radio.PowerLevel = PowerLevel.High;
         Radio.DataRate = DataRate.DR250Kbps;
         Radio.IsEnabled = true;

         Debug.WriteLine("Address: " + Encoding.UTF8.GetString(Radio.Address));
         Debug.WriteLine("PA: " + Radio.PowerLevel);
         Debug.WriteLine("IsAutoAcknowledge: " + Radio.IsAutoAcknowledge);
         Debug.WriteLine("Channel: " + Radio.Channel);
         Debug.WriteLine("DataRate: " + Radio.DataRate);
         Debug.WriteLine("IsDynamicAcknowledge: " + Radio.IsDyanmicAcknowledge);
         Debug.WriteLine("IsDynamicPayload: " + Radio.IsDynamicPayload);
         Debug.WriteLine("IsEnabled: " + Radio.IsEnabled);
         Debug.WriteLine("Frequency: " + Radio.Frequency);
         Debug.WriteLine("IsInitialized: " + Radio.IsInitialized);
         Debug.WriteLine("IsPowered: " + Radio.IsPowered);

         deferral = taskInstance.GetDeferral();

         Debug.WriteLine("Run completed");
      }

      private void Radio_OnDataReceived(byte[] data)
      {
         // Display as Unicode
         string unicodeText = Encoding.UTF8.GetString(data);
         Debug.WriteLine("Unicode - Payload Length {0} Unicode Length {1} Unicode text {2}", data.Length, unicodeText.Length, unicodeText);

         // display as hex
         Debug.WriteLine("Hex - Length {0} Payload {1}", data.Length, BitConverter.ToString(data));
      }

      private void Radio_OnTransmitSuccess()
      {
         Debug.WriteLine("Transmit Succeeded!");
      }

      private void Radio_OnTransmitFailed()
      {
         Debug.WriteLine("Transmit Failed!");
      }
   }
}

This was displayed in the output window of Visual Studio

Address: Base1
PA: 15
IsAutoAcknowledge: True
Channel: 10
DataRate: DR250Kbps
IsDynamicAcknowledge: False
IsDynamicPayload: True
IsEnabled: True
Frequency: 2410
IsInitialized: True
IsPowered: True
Run completed

Interrupt Triggered: FallingEdge
Unicode – Payload Length 19 Unicode Length 19 Unicode text T  23.8,H  73,V 3.26
Hex – Length 19 Payload 54-20-32-33-2E-38-2C-48-20-20-37-33-2C-56-20-33-2E-32-36
Interrupt Triggered: RisingEdge

Note the odd formatting of the Temperature and humidity values which is due to the way dtostrf function in the Atmel AVR library works.

Also noticed the techfooninja nRF24 library has configurable output power level which I will try to retrofit onto the Gralin NetMF library.

Next, several simple Arduino, devDuino V2.2, Seeeduino V4.2 and Netduino 2/3 clients (plus possibly some others)

nRF24 Windows 10 IoT Core reboot

My first live deployment of the nRF24L01 Windows 10 IoT Core field gateway is now scheduled for mid Q1 2018 so time for a reboot. After digging out my Raspbery PI 2/3 devices and the nRF24L01+ shield (with modifications detailed here) I have a basic plan with some milestones.

My aim is to be able to wirelessly acquire data from several dozen Arduino, devduino, seeeduino, and Netduino devices, Then, using a field gateway on a Raspberry PI running Windows 10 IoT Core upload it to Microsoft IoT Central

First bit of code – Bleepy a simple background application to test the piezo beeper on the RPI NRF24 Shield

namespace devmobile.IoTCore.Bleepy
{
   public sealed class StartupTask : IBackgroundTask
   {
      private BackgroundTaskDeferral deferral;
      private const int ledPinNumber = 4;
      private GpioPin ledGpioPin;
      private ThreadPoolTimer timer;

      public void Run(IBackgroundTaskInstance taskInstance)
      {
         var gpioController = GpioController.GetDefault();
         if (gpioController == null)
         {
            Debug.WriteLine("GpioController.GetDefault failed");
            return;
         }

         ledGpioPin = gpioController.OpenPin(ledPinNumber);
         if (ledGpioPin == null)
         {
            Debug.WriteLine("gpioController.OpenPin failed");
            return;
         }

         ledGpioPin.SetDriveMode(GpioPinDriveMode.Output);

         this.timer = ThreadPoolTimer.CreatePeriodicTimer(Timer_Tick, TimeSpan.FromMilliseconds(500));

         deferral = taskInstance.GetDeferral();

         Debug.WriteLine("Rum completed");
      }

      private void Timer_Tick(ThreadPoolTimer timer)
      {
         GpioPinValue currentPinValue = ledGpioPin.Read();

         if (currentPinValue == GpioPinValue.High)
         {
            ledGpioPin.Write(GpioPinValue.Low);
         }
         else
         {
            ledGpioPin.Write(GpioPinValue.High);
         }
      }
   }
}

Note the blob of blu tack over the piezo beeper to mute noise
nRF24ShieldMuted

Netduino + SeeedStudio Grove LCD RGB Backlight

For the last year I have been teaching introductory programing classes using Netduino devices and Seeedstudio sensors which were sponsored by Microsoft New Zealand. The kits are based on a Grove Starter Kit for Arduino/Genuino 101 which contain a Grove LCD RGB Backlight display.

Seeedstudio have published an Arduino driver for the display and it looks like Sirsnork used this as the basis for his Netduino NetMF Port. In class a few people have commented that they have had difficulty getting the driver to work on a Netduino 2 or Netduino Plus 2 device.

I think the two main issues are the lack of termination resistors on the Grove RGB Backlight. Possibly the missing R9 & R10 in the picture below?

SeeedStudioRGBLCDBack

I have found the easiest way to work around this issue is to have another I2C device (In this case it’s a Grove 3 Axis Accelerometer ±16G)

SeeedStudioNetduinoAndRGBLCD

The other is the need to strobe the Serial Data Line (SDA) of the I2C port on later Netduino devices to get it to work

using System;
using System.Threading;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;

namespace SeeedStudio.Grove.RGBLCD
{
   public class Program
   {
      public static void Main()
      {
         using (OutputPort i2cPort = new OutputPort(Pins.GPIO_PIN_SDA, true))
         {
            i2cPort.Write(false);
         }

.....

With the I2C bus terminated and the SDA port strobe I have found the Netduino and display work as expected.