Mikrobus.Net Quail, Weather & nRF-C clicks and xively

My next proof of concept uses a Weather click and nRF C click to upload temperature and humidity data to a Xively gateway running on a spare Netduino 2 Plus. I have a couple of Azure Event hub gateways (direct & queued) which require a Netduino 3 Wifi (for TLS/AMQPS support) and I’ll build a client for them in a coming post.

I initially purchased an nRF T click but something wasn’t quite right with its interrupt output. The interrupt line wasn’t getting pulled low at all so there were no send success/failure events. If I disabled the pull up resistor and strobed the interrupt pin on start-up the device would work for a while.

using (OutputPort Int = new OutputPort(socket.Int, true))


_irqPin = new InterruptPort(socket.Int, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);

The code sends a reading every 10 seconds and has been running for a couple of days. It strobes Led1 for each successful send and turns on Led2 when a send fails.

private static readonly byte[] deviceAddress = Encoding.UTF8.GetBytes("Quail");
private static readonly byte[] gatewayAddress = Encoding.UTF8.GetBytes("12345");
private const byte gatewayChannel = 10;
private const NRFC.DataRate gatewayDataRate = NRFC.DataRate.DR1Mbps;
private const int XivelyUpdateDelay = 10000;
private const char XivelyGatewayChannelIdTemperature = 'J';
private const char XivelyGatewayChannelIdHumidity = 'K';

public static void Main()
   NRFC nRF24Click = new NRFC(Hardware.SocketFour);
   nRF24Click.Configure(deviceAddress, gatewayChannel, gatewayDataRate);
   nRF24Click.OnTransmitFailed += nRF24Click_OnTransmitFailed;
   nRF24Click.OnTransmitSuccess += nRF24Click_OnTransmitSuccess;

   // Configure the weather click
   WeatherClick weatherClick = new WeatherClick(Hardware.SocketOne, WeatherClick.I2CAddresses.Address0);


   while (true)
      string temperatureMessage = XivelyGatewayChannelIdTemperature + weatherClick.ReadTemperature().ToString("F1");
      nRF24Click.SendTo(gatewayAddress, Encoding.UTF8.GetBytes(temperatureMessage));


      string humidityMessage = XivelyGatewayChannelIdHumidity + weatherClick.ReadHumidity().ToString("F1");
      nRF24Click.SendTo(gatewayAddress, Encoding.UTF8.GetBytes(humidityMessage));


static void nRF24Click_OnTransmitSuccess()
   if (MBN.Hardware.Led2.Read())


static void nRF24Click_OnTransmitFailed()


I need to have a look at interfacing some more sensors and soak testing the solution.

The MikroBus.Net team have done a great job with the number & quality of the drivers they have available.

Mikrobus.Net Quail, EthClick and xively

My second proof of concept application for the Mikrobus.Net Quail and EthClick uploads temperature and humidity data to Xively every 30 seconds for display and analysis.

Temperature and humidity Xively data stream

Temperature and humidity Xively data stream

The Xively REST API uses an HTTP PUT which initially didn’t work because the payload was not getting attached.

I patched the AssembleRequest method in the EtherClick driver to fix this issue.

private byte[] AssembleRequest()
   var a = RequestType;
   a += " " + Path + " " + Protocol + "\r\nHost: ";
   a += Host + "\r\n";

   foreach (object aHeader in Headers.Keys)
      a += (string)aHeader + ": " + (string)Headers[aHeader] + "\r\n";

   a += "\r\n"; // Cache-Control: no-cache\r\n  //Accept-Charset: utf-8;\r\n

   if (Content != null && Content != string.Empty && (RequestType == "POST" || RequestType == "PUT")) a += Content;

   return Encoding.UTF8.GetBytes(a);

The code reads the WeatherClick temperature and humidity values then assembles a CSV payload which it uploads with an HTTP PUT

public class Program
   private const string xivelyHost = @"api.xively.com";
   private const string xivelyApiKey = @"YourAPIKey";
   private const string xivelyFeedId = @"YourFeedID";

   public static void Main()
      WeatherClick weatherClick = new WeatherClick(Hardware.SocketOne, WeatherClick.I2CAddresses.Address0);

      EthClick ethClick = new EthClick(Hardware.SocketTwo);
      ethClick.Start(ethClick.GenerateUniqueMacAddress("devMobileSoftware"), "QuailDevice");

      // Wait for an internet connection
      while (true)
         if (ethClick.ConnectedToInternet)
            Debug.Print("Connected to Internet");
         Debug.Print("Waiting on Internet connection");

      while (true)
         Debug.Print("T " + weatherClick.ReadTemperature().ToString("F1") + " H " + weatherClick.ReadHumidity().ToString("F1") + " P " + weatherClick.ReadPressure(PressureCompensationModes.Uncompensated).ToString("F1"));

         HttpRequest request = new HttpRequest(@"http://" + xivelyHost + @"/v2/feeds/" + xivelyFeedId + @".csv");
         request.Host = xivelyHost;
         request.RequestType = "PUT";
         request.Headers.Add("Content-Type", "text/csv");
         request.Headers.Add("X-ApiKey", xivelyApiKey );

         request.Content = "OfficeT," + weatherClick.ReadTemperature().ToString("F1") + "\r\n" + "OfficeH," + weatherClick.ReadHumidity().ToString("F1") ;
         request.Headers.Add("Content-Length", request.Content.Length.ToString());

         var response = request.Send();
         if (response != null)
            Debug.Print("Response: " + response.Message);
            Debug.Print("No response");
MikrobustNet Quail with Eth and Weather Clicks

MikrobustNet Quail with Eth and Weather Clicks

This proof of concept code appears to be reliable and has run for days at a time. The IP stack looks like it needs a bit more work.

Netduino 3 Wifi xively nRF24L01 Gateway

The first version of this code acquired data from a number of *duino devices and uploaded it to xively for a week without any problems(bar my ADSL modem dropping out every so often which it recovered from without human intervention). The data streams are the temperature and humidity for the three bedrooms in my house (the most reliable stream is Bedroom 1). Next version will use the new Netduino.IP stack and run on a Netduino 2 Plus

Netduino 3 Wifi with nRF24L01 shield

Netduino 3 Wifi + nRF24L01 shield

To make the software easy to setup all the gateway configuration is stored on a MicroSD and can be modified with a text editor. When the application starts it looks for a file in the root directory of the MicroSD card called app.config. If the file does not exist an empty template is created.


The first byte of each (upto 32 byte) nRF24L01 message is used to determine the Xively channel.

For testing I used a simple *duino program which uploads temperature and humidity readings every 5 seconds. It’s not terribly efficient or elegant and is just to illustrate how to package up the data.

#include <RF24_config>
#include <nRF24L01.h>
#include <SPI.h>
#include <RF24.h>
#include "Wire.h"
#include <TH02_dev.h>

//UNO R3 with embedded coolness board
//RF24 radio(3, 7);
//devDuino  with onboard
RF24 radio(8, 7);

char payload[32] = "";
const uint64_t pipe = 0x3165736142LL; // Base1 pay attention to byte ordering and address length

void setup()



  /* Power up,delay 150ms,until voltage is stable */



void loop()
  float temperature = TH02.ReadTemperature();
  float humidity = TH02.ReadHumidity();


  payload[0] = 'A';
  dtostrf(temperature, 5, 1, &payload[1]);
  boolean result = radio.write(payload, strlen(payload));
  if (result)
    Serial.println("T Ok...");
    Serial.println("T failed.");

  payload[0] = 'B';
  dtostrf(humidity, 5, 1, &payload[1]);
  result = radio.write(payload, strlen(payload));
  if (result)
    Serial.println("H Ok...");
    Serial.println("H failed.");



The gateway code creates a thread for each call to the Xively REST API. (In future the code may need to limit the number of concurrent requests)

private void OnReceive(byte[] data)

   // Ensure that we have a valid payload
   if ( data.Length == 0 )
      Debug.Print( "ERROR - Message has no payload" ) ;
      return ;

   // Extract the device id
   string deviceId = xivelyApiChannleIDPrefix + data[0].ToString();
   string message = new String(Encoding.UTF8.GetChars(data, 1, data.Length - 1));

   string xivelyApiChannel = appSettings.GetString( deviceId, string.Empty ) ;
   if ( xivelyApiChannel.Length == 0 )
      Debug.Print("ERROR - Inbound message has unknown channel " + deviceId);
      return ;
   Debug.Print(DateTime.Now.ToString("HH:mm:ss") + " " + xivelyApiChannel + " " + message); ;

   Thread thread = new Thread(() =&gt; xivelyFeedUpdate(xivelyApiChannel, message ));

private void xivelyFeedUpdate( string channel, string value)
   #region Assertions
   Debug.Assert(channel != null);
   Debug.Assert(channel != string.Empty );
   Debug.Assert(value != null);

      WebProxy webProxy = null;

      if (webProxyAddress.Length &gt; 1)
         webProxy = new WebProxy(webProxyAddress, webProxyPort);

      using (HttpWebRequest request = (HttpWebRequest)WebRequest.Create(xivelyApiBaseUrl + xivelyApiFeedID + xivelyApiEndpoint))
         byte[] buffer = Encoding.UTF8.GetBytes(channel + "," + value);

         DateTime httpRequestedStartedAtUtc = DateTime.UtcNow;

         if (webProxy != null)
            request.Proxy = webProxy;
         request.Method = "PUT";
         request.ContentLength = buffer.Length;
         request.ContentType = xivelyApiContentType;
         request.Headers.Add("X-ApiKey", xivelyApiKey);
         request.KeepAlive = false;
         request.Timeout = httpRequestTimeoutmSec;
         request.ReadWriteTimeout = httpRequestReadWriteTimeoutmSec;

         // request body
         Debug.Print("HTTP request");
         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());
   catch (Exception ex)

To use this code download the Nordic nRF24L01 library from Codeplex then include that plus my Netduino NRF24L01 Xively Gateway in a new solution and it should just work.

Deploy the application to a Netduino 2 Plus or Netduino 3 Wifi device and run it to create the app.config file, then use a text editor to update the file with your Xively & device settings.

I’ll upload this and a couple of other projects to GitHub shortly.

Bill of materials (prices as at July 2015)

Netduino 3 Wifi xively nRF24L01 Gateway data stream live

The gateway is now live, I’m regularly updating the Netduino 3 wifi code and the client arduino, devDuino + netduino devices so there maybe short periods of downtime and/or missing data points.

The stream is available here and is currently just temperature and humidity readings from two bedrooms updating roughly once a minute.

I live in New Zealand which is currently UTC + 12.