nRF24 Windows 10 IoT Core Test Harness

After modifying the Raspbery PI nRF24L01 shields I built a single page single button Universal Windows Platforms(UWP) test harness (using the techfooninja RF24 library) to check everything was working as expected.

I used a couple of Netduinos and Raspbery PI devices to as test clients.

public sealed partial class MainPage : Page
{
   private const byte ChipEnablePin = 25;
   private const byte ChipSelectPin = 0;
   private const byte InterruptPin = 17;
   private const byte Channel = 10;
   private RF24 radio;

   public MainPage()
   {
      this.InitializeComponent();

      this.radio = new RF24();

      this.radio.OnDataReceived += this.Radio_OnDataReceived;
      this.radio.OnTransmitFailed += this.Radio_OnTransmitFailed;
      this.radio.OnTransmitSuccess += this.Radio_OnTransmitSuccess;

      this.radio.Initialize(ChipEnablePin, ChipSelectPin, InterruptPin);
      this.radio.Address = Encoding.UTF8.GetBytes("Base1");
      this.radio.Channel = Channel;
      this.radio.PowerLevel = PowerLevel.Low;
      this.radio.DataRate = DataRate.DR250Kbps;

      this.radio.IsEnabled = true;

      Debug.WriteLine("Address: " + Encoding.UTF8.GetString(this.radio.Address));
      Debug.WriteLine("Channel: " + this.radio.Channel);
      Debug.WriteLine("DataRate: " + this.radio.DataRate);
      Debug.WriteLine("PA: " + this.radio.PowerLevel);
      Debug.WriteLine("IsAutoAcknowledge: " + this.radio.IsAutoAcknowledge);
      Debug.WriteLine("IsDynamicAcknowledge: " + this.radio.IsDynamicAcknowledge);
      Debug.WriteLine("IsDynamicPayload: " + this.radio.IsDynamicPayload);
      Debug.WriteLine("IsEnabled: " + this.radio.IsEnabled);
      Debug.WriteLine("IsInitialized: " + this.radio.IsInitialized);
      Debug.WriteLine("IsPowered: " + this.radio.IsPowered);
   }

   private void Radio_OnDataReceived(byte[] data)
   {
     string dataUTF8 = Encoding.UTF8.GetString(data);

     Debug.WriteLine(string.Format("Received: {0}", dataUTF8));
   }

   private void buttonSend_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
   {
      this.radio.SendTo(Encoding.UTF8.GetBytes("Duino"), Encoding.UTF8.GetBytes(DateTime.UtcNow.ToString("yy-MM-dd hh:mm:ss"))) ;
   }

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

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

Interrupt Triggered: FallingEdge
Data Sent!
Radio_OnTransmitSuccess
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
Received: 20.4 70.7
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
Data Sent!
Radio_OnTransmitSuccess
Interrupt Triggered: RisingEdge
Interrupt Triggered: FallingEdge
Received: 20.3 70.8
Interrupt Triggered: RisingEdge

The Raspberry PI could reliably receive and transmit messages.

nRF24 Windows 10 IoT Core Hardware

Taking my own advice I decided to purchase a couple of Raspberry Pi to NRF24L01 shields from Ceech a vendor on Tindie.

The nRF24L01 libraries for my .Net Micro framework and WIndows 10 IoT Core devices use an interrupt driver approach rather than polling status registers to see what is going on.

Like most Raspberry PI shields intended to be used with a *nix based operating system the interrupt pin was not connected to a General Purpose Input/Output (GPIO) pin.

NRF24PiPlateModification

My first step was to add a jumper wire from the pin 8 on the nRF24L01 to GPIO pin 17 on Raspberry PI connector.

I then downloaded the techfooninja Radios.RF24 library for Windows IoT core and update the configuration to suit my modifcations. In the TestApp the modifications were limited to changing the interrupt pin from GPI 4 to GPO 17

private const byte IRQ_PIN = 4;

private const byte IRQ_PIN = 17;

I used a socket for the nRF24L01 device so I can trial different devices, for a production system I would solder the device to the shield to improve reliability.

RPiWithnRF24Plate

I then ran the my test application software in a stress test rig overnight to check for any reliability issues. The 5 x netduino devices were sending messages every 500mSec

RPIStressTester

nRF24L01 Raspberry PI Gateway Hardware

For those who came to my MS Ignite AU Intelligent Cloud booth session

Building Wireless Field Gateways

Connecting wireless sensor nodes to the cloud is not the mission it used to be, because the Azure team (and many OS projects) have developed tooling which can help hobbyist and professional developers build solutions. How could you build a home scale robust, reliable and secure solution with off the shelf kit without blowing the budget?

Sparkfun nRF24L01 module &Adafruit perma proto hat

NRF24L01 Raspberry PI DIY Gateway Hardware

BoM (all prices as at Feb 2016)

You will also need some short lengths of wire and a soldering iron.

For those who want an “off the shelf” solution (still requires a minor modification for interrupt support) I have used the Raspberry Pi to NRF24l01+ Shield USD9.90

2015-09-25t072754-447z-20150925_091942-855x570_q85_pad_rcrop

Instructions for modifications and software to follow.

Mikrobus.Net Quail Robot

In a previous post I had replaced a Netduino and Elecfreaks Joystick shield based remote control with a MikrobusNet Quail, thumbstick click and an nRF-C click. The next step was to replace the Netduino on the robot chassis with a MikrobusNet Quail, a pair of DC Motor Clicks and an nRF-C click.

Bill of materials (prices in USD as at Feb 2016)

The first version of the robot uses a pair of battery packs one for the motors the other for the Quail board.

MikrobusNetQual4WDRobot

The drivers developed by MikroBUSNet team greatly reduced the amount of code I had to write to get the robot to work.

public class Program
{
   private static double Scale = 100.0;
   private static byte RobotControlChannel = 10;
   private static byte[] ControllerAddress = Encoding.UTF8.GetBytes("RC1");
   private static byte[] RobotAddress = Encoding.UTF8.GetBytes("RB1");
   private static TimeSpan MessageMaximumInterval = new TimeSpan(0, 0, 1);
   private static DateTime _MessageLastReceivedAt = DateTime.UtcNow;
   private static DCMotorClick motor1 = new DCMotorClick(Hardware.SocketOne);
   private static DCMotorClick motor2 = new DCMotorClick(Hardware.SocketTwo);

public static void Main()
{
   NRFC nrf = new NRFC(Hardware.SocketFour);
   nrf.Configure(RobotAddress, RobotControlChannel);
   nrf.OnTransmitFailed += nrf_OnTransmitFailed;
   nrf.OnTransmitSuccess += nrf_OnTransmitSuccess;
   nrf.OnDataReceived += nrf_OnDataReceived;
   nrf.Enable();

   Timer CommunicationsMonitorTimer = new Timer(CommunicationsMonitorTimerProc, null, 500, 500);

   Thread.Sleep(Timeout.Infinite);
}

static void nrf_OnDataReceived(byte[] data)
{
   Hardware.Led1.Write(true);
   _MessageLastReceivedAt = DateTime.UtcNow;

   if (data.Length != 5)
   {
   return;
   }

   Debug.Print("M1D=" + data[0].ToString() + " M2D=" + data[1].ToString() + " M1S=" + data[2].ToString() + " M2S=" + data[3].ToString());
   if (data[0] == 1)
   {
      motor1.Move(DCMotorClick.Directions.Forward, (data[2] / Scale ));
   }
   else
   {
     motor1.Move(DCMotorClick.Directions.Backward, (data[2] / Scale ));
   }

   if (data[1] == 1)
   {
      motor2.Move(DCMotorClick.Directions.Forward, (data[3] / Scale ));
   }
   else
   {
      motor2.Move(DCMotorClick.Directions.Backward, (data[3] / Scale ));
   }
}

private static void CommunicationsMonitorTimerProc(object status)
{
   if ((DateTime.UtcNow - _MessageLastReceivedAt) > MessageMaximumInterval)
   {
      Debug.Print("Communications timeout");

      motor1.Move(MBN.Modules.DCMotorClick.Directions.Forward, 0.0);
      motor2.Move(MBN.Modules.DCMotorClick.Directions.Forward, 0.0);
   }
}

I have kept the communications monitoring functionality which stops the motors when the robot gets out of range of the remote control software fails.

 

 

 

Mikrobus.Net Quail Robot Remote Control

In a previous pair of posts  (part1 & part2) in February 2014 I built a 4WD Robot and remote control using a pair of Netduinos, an elecfreaks Smart Car Chassis 4WD, an elecfreaks joystick 2.4, an Embedded coolness nRF24Lo1 shield and a Pololu MC33926 motor shield.

My Quail device looked like a good platform for building a handheld control with a different form factor.

Bill of materials (prices in USD as at Jan 2016)

Quail4WDRobotController

The Quail device and battery pack aren’t quite small enough to work with one hand. A Mikrobus.Net Dalmatian or Tuatara based remote might be easier to use.

I tried using the thumbstick button pushed message for the horn functionality but it made the throttle and heading jump.

The first version of the code is just to test the wireless link, the motor speed code needs a little work.(Currently the device won’t rotate with motors going in opposite directions)

public class Program
{
   private const double Deadband = 0.1;
   private static double Scale = 100.0;
   private static byte RobotControlChannel = 10;
   private static byte[] ControllerAddress = Encoding.UTF8.GetBytes("RC1");
   private static byte[] RobotAddress = Encoding.UTF8.GetBytes("RB1");

   public static void Main()
   {
      ThumbstickClick thumbStick = new ThumbstickClick(Hardware.SocketThree);
      thumbStick.ThumbstickOrientation = ThumbstickClick.Orientation.RotateZeroDegrees;
      thumbStick.Calibrate();

      NRFC nrf = new NRFC(Hardware.SocketFour);
      nrf.Configure(ControllerAddress, RobotControlChannel );
      nrf.OnTransmitFailed += nrf_OnTransmitFailed;
      nrf.OnTransmitSuccess += nrf_OnTransmitSuccess;
      nrf.Enable();

      while (true)
      {
         byte motor1Direction, motor2Direction;
         byte motor1Speed, motor2Speed;
         double x = thumbStick.GetPosition().X;
         double y = thumbStick.GetPosition().Y;

         Debug.Print("X=: + x.ToString("F1") + " Y=" + y.ToString("F1") + " IsPressed=" + thumbStick.IsPressed);

         // See if joystick x or y is in centre deadband
         if (System.Math.Abs(x) < Deadband)
         {
            x = 0.0;
         }

         // See if joystick y is in centre deadband
         if (System.Math.Abs(y) < Deadband)
         {
            y = 0.0;
         }

         // Set direction of both motors, no swivel on spot yet
         if (y >= 0.0)
         {
            motor1Direction = (byte)1;
            motor2Direction = (byte)1;
         }
         else
         {
            motor1Direction = (byte)0;
            motor2Direction = (byte)0;
         }

         // Straight ahead/backward
         if (x == 0.0)
         {
            motor1Speed = (byte)(System.Math.Abs(y) * Scale);
            motor2Speed = (byte)(System.Math.Abs(y) * Scale);
         }
         // Turning right
         else if (x > 0.0)
         {
            motor1Speed = (byte)(System.Math.Abs(y) * Scale);
            motor2Speed = (byte)(System.Math.Abs(y) * (1.0 - System.Math.Abs(x)) * Scale);
         }
         // Turning left
         else
         {
            motor1Speed = (byte)(System.Math.Abs(y) * (1.0 - System.Math.Abs(x)) * Scale);
            motor2Speed = (byte)(System.Math.Abs(y) * Scale);
         }

         Debug.Print("X=" + x.ToString("F1") + " Y=" + y.ToString("F1") + " IsPressed=" + thumbStick.IsPressed + " M1D=" + motor1Direction.ToString() + " M2D=" + motor2Direction.ToString() + " M1S=" + motor1Speed.ToString() + " M2S=" + motor2Speed.ToString());

         byte[] command =
         {
            motor1Direction,
            motor2Direction,
            motor1Speed,
            motor2Speed,
            (byte)0)
         };
         nrf.SendTo(RobotAddress, command );

         MBN.Hardware.Led1.Write(true);

         Thread.Sleep(250);
      }
   }

   static void nrf_OnTransmitSuccess()
   {
     MBN.Hardware.Led1.Write(false);
     Debug.Print("nrf_OnTransmitSuccess");
   }

   static void nrf_OnTransmitFailed()
   {
      Debug.Print("nrf_OnTransmitFailed");
   }
}

The Mikrobus.Net team have done a great job with the number and quality of the drivers for the Mikroe click boards. The Mikroe click boards are individually packaged with professionally written click specific and handling instructions.

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))
{
 Int.Write(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(&quot;Quail&quot;);
private static readonly byte[] gatewayAddress = Encoding.UTF8.GetBytes(&quot;12345&quot;);
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;
   nRF24Click.Enable();

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

   Thread.Sleep(XivelyUpdateDelay);

   while (true)
   {
      string temperatureMessage = XivelyGatewayChannelIdTemperature + weatherClick.ReadTemperature().ToString("F1");
      Debug.Print(temperatureMessage);
      MBN.Hardware.Led1.Write(true);
      nRF24Click.SendTo(gatewayAddress, Encoding.UTF8.GetBytes(temperatureMessage));

      Thread.Sleep(XivelyUpdateDelay);

      string humidityMessage = XivelyGatewayChannelIdHumidity + weatherClick.ReadHumidity().ToString("F1");
      Debug.Print(humidityMessage);
      MBN.Hardware.Led1.Write(true);
      nRF24Click.SendTo(gatewayAddress, Encoding.UTF8.GetBytes(humidityMessage));

      Thread.Sleep(XivelyUpdateDelay);
   }
}

static void nRF24Click_OnTransmitSuccess()
{
   MBN.Hardware.Led1.Write(false);
   if (MBN.Hardware.Led2.Read())
   {
      MBN.Hardware.Led2.Write(false);
   }

   Debug.Print("nRF24Click_OnTransmitSuccess");
}

static void nRF24Click_OnTransmitFailed()
{
   MBN.Hardware.Led2.Write(true);

   Debug.Print("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.

Netduino 3 Wifi Queued Azure Event Hub Field Gateway V1.0

My ADSL connection had been a bit flaky which had meant I had lost some sensor data with my initial Azure Event Hub gateway. In attempt make the solution more robust this version of the gateway queues unsent messages using the on-board MicroSD card support.

The code assumes that a file move is an “atomic operation”, so it streams the events received from the devices into a temporary directory (configurable) then moves them to the upload directory (configurable).

This code is proof of concept and needs to be soak tested, improved error handling and some additional multi threading locking added plus the magic constants refactored.

This code is called in the nRF24 receive messages handler

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

   // Ensure that we have a payload
   if (data.Length < 1 )
   {
      Debug.Print( "ERROR - Message has no payload" ) ;
      return ;
   }

   string message = new String(Encoding.UTF8.GetChars(data));
   Debug.Print("+" + DateTime.UtcNow.ToString("HH:mm:ss") + " L=" + data.Length + " M=" + message);

   string filename = DateTime.UtcNow.ToString("yyyyMMddhhmmssff") + ".txt";

   string tempDirectory = Path.Combine("\\sd", "temp");
   string tempFilePath = Path.Combine(tempDirectory, filename);

   string queueDirectory = Path.Combine("\\sd", "data");
   string queueFilePath = Path.Combine(queueDirectory, filename);

   File.WriteAllBytes(tempFilePath, data);

   File.Move(tempFilePath, queueFilePath);

   new Microsoft.SPOT.IO.VolumeInfo("\\sd").FlushAll();
}

A timer initiates the upload process which uses the AMQPNetlite library

bool UploadInProgress = false;

      
void uploaderCallback(object state)
{
   Debug.Print("uploaderCallback - start");

   if (UploadInProgress)
   {
      return;
   }
   UploadInProgress = true;

   string[] eventFilesToSend = Directory.GetFiles(Path.Combine("\\sd", "data")) ;

   if ( eventFilesToSend.Length == 0 )
   {
      Debug.Print("uploaderCallback - no files");
      UploadInProgress = false;
      return ;
   }

   try
   {
      Debug.Print("uploaderCallback - Connect");
      Connection connection = new Connection(new Address(serviceBusHost, serviceBusPort, serviceBusSasKeyName, serviceBusSasKey));

      Session session = new Session(connection);

      SenderLink sender = new SenderLink(session, "send-link", eventHubName);

      for (int index = 0; index < System.Math.Min(eventUploadBatchSizeMaximum, eventFilesToSend.Length); index++)
      {
         string eventFile = eventFilesToSend[ index ] ;

         Debug.Print("-" + DateTime.UtcNow.ToString("HH:mm:ss") + " " + eventFile ); ;

         Message message = new Message()
         {
            BodySection = new Data()
            {
               Binary = File.ReadAllBytes(eventFile),
            },
         ApplicationProperties = new Amqp.Framing.ApplicationProperties(),
         };

         FileInfo fileInfo = new FileInfo(eventFile);

         message.ApplicationProperties["AcquiredAtUtc"] = fileInfo.CreationTimeUtc;
         message.ApplicationProperties["UploadedAtUtc"] = DateTime.UtcNow;
         message.ApplicationProperties["GatewayId"] = gatewayId;
         message.ApplicationProperties["DeviceId"] = deviceId;
         message.ApplicationProperties["EventId"] = Guid.NewGuid();

         sender.Send(message);

         File.Delete(eventFile);

         new Microsoft.SPOT.IO.VolumeInfo("\\sd").FlushAll();
      }

      sender.Close();
      session.Close();
      connection.Close();
   }
   catch (Exception ex)
   {
      Debug.Print("ERROR: Upload failed with error: " + ex.Message);
   }
   finally
   {
      Debug.Print("uploaderCallback - finally");
      UploadInProgress = false;
   }
}

The timer period and number of files uploaded in each batch is configurable. I need to test the application to see how it handles power outages and MicroSD card corruption. The source is Netduino NRF24L01 AMQPNetLite Queued Azure EventHub Gatewaywith all the usual caveats.

This project wouldn’t have been possible without