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

NetMF MP3 Player Part 3

Building on the file listing code from the previous post in the next class we built a basic multi threaded music player using an enhanced version of the Vs1053B driver based on the softelectrotech.and bluecone code.

The code uses five interrupt ports (I used 5 buttons on the 4 analog ports on the Seeedstudio V2 Base shield and D5 to make it easier to fit the Mp3 shield)

As the Vs1053 driver is now running asynchronously it fires an event when the current track has finished playing

   public class Program
   {
      static string[] MusicFiles;
      static Vs1053B player = new Vs1053B(Pins.GPIO_PIN_D2, Pins.GPIO_PIN_D6, Pins.GPIO_PIN_D7, Pins.GPIO_PIN_D8);
      static byte volume = 200;
      static int trackNumber = 1;
      static public string TrackFilename { get { return MusicFiles[trackNumber - 1]; } }

      public static void Main()
      {
         MusicFiles = Directory.GetFiles(@"\SD");

         foreach( string file in MusicFiles)
         {
            Debug.Print(file);
         }

         InterruptPort playPause = new InterruptPort(Pins.GPIO_PIN_D5, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);
         playPause.OnInterrupt += playPause_OnInterrupt;

         InterruptPort volumeUp = new InterruptPort(Pins.GPIO_PIN_A0, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);
         volumeUp.OnInterrupt += volumeUp_OnInterrupt;

         InterruptPort volumeDown = new InterruptPort(Pins.GPIO_PIN_A1, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);
         volumeDown.OnInterrupt += volumeDown_OnInterrupt;

         InterruptPort previousTrack = new InterruptPort(Pins.GPIO_PIN_A2, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);
         previousTrack.OnInterrupt += previousTrack_OnInterrupt;

         InterruptPort nextTrack = new InterruptPort(Pins.GPIO_PIN_A3, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);
         nextTrack.OnInterrupt += nextTrack_OnInterrupt;

         player.SetVolume(volume);
         player.Filename = TrackFilename;
         player.onMusicFinished += player_onMusicFinished;

         player.Play();

         Thread.Sleep(Timeout.Infinite);
      }

      static void player_onMusicFinished()
      {
         trackNumber += 1;

         if (trackNumber > MusicFiles.Length)
         {
            trackNumber = 1;
         }
         Debug.Print("player_onMusicFinished " + trackNumber + " of " + MusicFiles.Length);

         player.Filename = TrackFilename;
      }

      static void previousTrack_OnInterrupt(uint data1, uint data2, DateTime time)
      {
         trackNumber -= 1;

         if (trackNumber < 1)          {             trackNumber = MusicFiles.Length;          }          Debug.Print("previousTrack_OnInterrupt " + trackNumber + " of " + MusicFiles.Length);          player.CancelPlayback();          player.Filename = TrackFilename;       }       static void nextTrack_OnInterrupt(uint data1, uint data2, DateTime time)       {          trackNumber += 1;          if (trackNumber > MusicFiles.Length)
         {
            trackNumber = 1;
         }
         Debug.Print("nextTrack_OnInterrupt " + trackNumber + " of " + MusicFiles.Length);

         player.CancelPlayback();
         player.Filename = TrackFilename;
      }

      static void playPause_OnInterrupt(uint data1, uint data2, DateTime time)
      {
         Debug.Print("playPause_OnInterrupt ");
         if (player.IsPaused())
         {
            player.Resume();
         }
         else
         {
            player.Pause();
         }
      }

      static void volumeDown_OnInterrupt(uint data1, uint data2, DateTime time)
      {
         Debug.Print("volumeDown_OnInterrupt " + volume);
         if (volume > 0)
         {
            volume -= 1;
         }
         player.SetVolume(volume);
      }

      static void volumeUp_OnInterrupt(uint data1, uint data2, DateTime time)
      {
         Debug.Print("volumeUp_OnInterrupt " + volume);
         if (volume < 255)
         {
            volume += 1;
         }
         player.SetVolume(volume);
      }
   }

Next steps are to ignore contact bounce on the buttons and play MP3 files in a more consistent order
musicplayerv2

Netduino with Mp3 Shield and 5 button UI

Netduino Mp3 player with 5 button UI

NetMF MP3 Player Part 2

Building on the file listing code from the previous post in the next class we wrote the simplest possible NetMF code to play all of MP3 files on an SD Card. The Mp3 player shields I have all use a Vs1053B chip to decode the MP3 byte stream. This sample uses the driver code from softelectrotech.

public static void Main()
{
   Vs1053B player = new Vs1053B(Pins.GPIO_PIN_D2, Pins.GPIO_PIN_D6, Pins.GPIO_PIN_D7, Pins.GPIO_PIN_D8);
   string[] MusicFiles = Directory.GetFiles(@"\SD");
   player.SetVolume(180, 180);

   // Print a list of all the files on the SD card.
   foreach (string file in MusicFiles)
   {
      Debug.Print(file);
   }

   foreach (string file in MusicFiles)
   {
      Debug.Print("Play start " + file);

      player.Play(file, true);

      Debug.Print("Play finish " + file);
   }
}

Some of the students observed the order of the files was not what they were expecting. The order of the files appeared to depend on how they were copied to the memory card.

\SD\05 Sunday Bloody Sunday.mp3
\SD\06 Bad.mp3
\SD\07 Where the Streets Have No Name.mp3
\SD\08 I Will Follow.mp3
\SD\09 The Unforgettable Fire.mp3
\SD\10 Sweetest Thing [The Single Mix].mp3
\SD\11 Desire.mp3
\SD\12 When Love Comes to Town.mp3
\SD\13 Angel of Harlem.mp3
\SD\14 All I Want Is You.mp3
\SD\01 Pride (In the Name of Love).mp3
\SD\02 New Year's Day.mp3
\SD\03 With or Without You.mp3
\SD\04 I Still Haven't Found What I'm Looking For.mp3
Playback
Play start \SD\05 Sunday Bloody Sunday.mp3
Play finish \SD\05 Sunday Bloody Sunday.mp3
Play start \SD\06 Bad.mp3

All of the students observed that the tacks were being played synchronously which didn’t allow you to change the volume or interrupt the playback to pause the current track or change the track being played.

The next steps were to ensure the music files were sorted into a consistent order and that playback was not synchronous.

MusicPlayerSyncBasic code

NetMF MP3 Player Part 1

For one of my class projects the students build an NetMF MP3 player using a Netduino, MP3 shield, MicroSD card and some code. The first step is to learn about files, and directories by enumerating the contents of the MicroSD card.

public static void Main()
 {
    string[] musicFiles = Directory.GetFiles(@"\SD");

    foreach (string musicFile in musicFiles)
    {
       Debug.Print(musicFile);
    }
}

The NetMF implementation of GetFiles doesn’t support wildcards (unlike the full .Net Framework) so the list of files has to be manually filtered.

public static void Main()
{
   string[] musicFiles = Directory.GetFiles(@"\SD");

   foreach (string musicFile in musicFiles)
   {
      if (filePath.IndexOf(".mp3") != -1)
      {
         Debug.Print(musicFile);
      }
   }
}

The code above displayed
\SD\01 Pride (In the Name of Love).mp3
\SD\02 New Year’s Day.mp3
\SD\03 With or Without You.mp3
\SD\04 I Still Haven’t Found What I’m Looking For.mp3
\SD\05 Sunday Bloody Sunday.mp3
\SD\06 Bad.mp3
\SD\07 Where the Streets Have No Name.mp3
\SD\08 I Will Follow.mp3
\SD\09 The Unforgettable Fire.mp3
\SD\10 Sweetest Thing [The Single Mix].mp3
\SD\11 Desire.mp3
\SD\12 When Love Comes to Town.mp3
\SD\13 Angel of Harlem.mp3
\SD\14 All I Want Is You.mp3

For this project Directory.GetFiles was used (rather than Directory.EnumerateFiles) because the list files on the MicroSD will be used in other parts of the application.

The parsing and processing of file paths is important and can if done wrong can introduce hard to find issues(e.g. directory traversal attacks)

Debug.Print(musicFile .Substring( 0, musicFile.LastIndexOf(".mp3")));

Updating the code to use the built in System.IO.Path functionality

public static void Main()
{
   string[] MusicFiles = Directory.GetFiles(@"\SD");

   foreach (string musicFile in MusicFiles)
   {
      if (Path.GetExtension(musicFile) == ".mp3" )
      {
         Debug.Print(Path.GetFileNameWithoutExtension(musicFile));
      }
   }
}

The next step is to load and play the MP3 files using a provided library.

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.

NetMF Electric Longboard Part 2

In part 1 I got the wireless WiiChuck working with a plug n play setup using a SeeedStudio Grove base shield, Wii Chuck adaptor, modified 5CM cable and FEZ Lemur. The FEZ Lemur is limited to a 5VDC supply which wasn’t going to work so well with the 6VDC output of my HobbyKing HK150 ESC without some extra electronics.

GHI Electronics also sell the FEZ Panda III which has a 6VDC-9VDC voltage range and more processing power which would be useful for my next project a dual motor longboard with traction control and anti lock braking .

I also figured vibration could be a problem for the plug n play setup so I built a custom shield for my wireless Wii Chuck dual motor longboard control using an Arduino protoshield, and a Wii-Nunchuck breakout board. The shield provides a solid mount for the wireless Wii chuck dongle and power for the NetMF board from the output of the ESC.

 

FEZ Panda III Protoshield for longboard with RC Servo for testing

FEZ Panda II Protoshield for longboard RC Servo test

I tested the shield wiring using a Radio Control (RC) Servo so the scope of disaster was greatly reduced. (The red jumper wire is supplying 3v3 to the servo for testing)

using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Toolbox.NETMF.Hardware;

public class Program
{
   private const int NunchukYMinimum = 0;
   private const int NunchukYMaximum = 255;
   private const int PWMPeriodMicroseconds = 20000;
   private const int DurationMinimum = 1250;
   private const int DurationMaximum = 1750;

   public static void Main()
   {
      WiiNunchuk Nunchuk = new WiiNunchuk();
      PWM pwm = new PWM(GHI.Pins.FEZPandaIII.PwmOutput.D6, PWMPeriodMicroseconds, DurationMinimum, PWM.ScaleFactor.Microseconds, false);

      pwm.Start();

      while (true)
      {
         // Reads all values
         Nunchuk.Read();

         Debug.Print(Nunchuk.AnalogStickX.ToString() + " " + Nunchuk.AnalogStickY.ToString());

         uint duration = (uint)map(Nunchuk.AnalogStickY, NunchukYMinimum, NunchukYMaximum, DurationMinimum, DurationMaximum);

         Debug.Print("Duration " + duration.ToString());
         pwm.Duration = duration;

         Thread.Sleep(100);
      }
   }

   private static long map(long x, long inputMinimum, long inputMaximum, long outputMinimum, long outputMaximum)
   {
      return (x - inputMinimum) * (outputMaximum - outputMinimum) / (inputMaximum - inputMinimum) + outputMinimum;
   }
}

I then connected the setup to my longboard ESC and it worked. (need a right angle connection for FEZ Panda III power)

Longboard with FEZ Panda III board based controller

Longboard with FEZ Panda III board based controller

The proof of concept software worked, the next step is to add throttle mapping and failure mode handling e.g. loss of communications with the Wiichuck.

NetMF Electric Longboard Part 1

When I first built my electric longboard I started with a devicter devduino V2 running a modified version of the Wiiceiver code from AustinDavid.com. This plug n play setup has worked really well and proved quite robust considering the hostile environment it is working in.

devduino V2 longboard controller, wiresless Wiichuck ESC and batteries

devduino V2 controller

I had been thinking about purchasing a dual motor kit and experimenting with traction control and anti lock braking (after a couple of close calls indoor on a tiled floor) which would require a bit more processing power.

The first version of my NetMF controller will be powered by a GHI Electronics FEZ Lemur which is an ARM Cortex M4 based System on a Chip (SoC) running at 84MHz.

The FEZ Lemur is an Arduino pinout-compatible mainboard but with the Inter-Integrated Circuit (I2C) pins on D2-Serial Data Line(SDA) and D3-Serial Clock Line (SCL).

My first proof of concept (PoC) uses a standard wii Nunchuk and some jumper wires.

FEZ Lemur and Nunchuck connected with jumper wires and seeedstudio adaptor

FEZ Lemur Wii NunChuck interface

Bill of materials (Prices in USD as at Mar 2016)

I then tested my hardware setup with an application based on the driver software written by Szymon Kobalczyk and it worked. I have used this software on a couple of projects but have never been able to get to work with my wireless Wii Nunchuk.

I compared the Arduino wiiceiver code and the C# version and found the initialisation process was different. I then did some research and found that the WiiNunChuk driver of the .Net Micro Framework Toolbox by Stefan Thoolen used a similar approach as the wiiceiver code.

using System;
using System.Threading;
using Microsoft.SPOT;
using Toolbox.NETMF.Hardware;

public class Program
{
   public static void Main()
   {
      WiiNunchuk nunchuk = new WiiNunchuk();

      while (true)
      {
         // Reads all values
         nunchuk.Read();

         Debug.Print(nunchuk.AnalogStickX + " " + nunchuk.AnalogStickY);

         Thread.Sleep(100);
      }
   }
}

I then tried the wireless Wii NunChuk device and it worked (The tape is to stop the wireless dongle falling off due to vibration when mounted on my skateboard)

FEZ Lemur Wireless Wii NunChuck interface

FEZ Lemur Wireless Wii NunChuck interface

The PoC was working so now I needed to make it more robust and plug n play. For many of my projects I use the Seeedstudio Grove system which provides plug n play digital inputs, digital outputs, analog inputs and I2C connectivity for *duino (and other) format devices.

The Seeedstudio base shield V2 can be configured for *duino devices which implement I2C connectivity on the Analog Input pins 4 & 5 or dedicated pins SDA & SCL pins.

FEZ Lemur Wireless Wii NunChuck PnP interface

FEZ Lemur Wireless Wii NunChuck interface

To get the SeeedStudion Base Shield to work with my FEZ Lemur I had to put a twist in the jumper cable to get the SDA & SCL the right way round and plug it into the D2 socket.

NOTE : put some tape on the top of the MicroSD card socket to stop a accidental short circuit.

Seeedstudio 5CM cable with SDA & SCL Pins reversed.

5CM cable with SDA & SCL Pins reversed

Connecting to G30_G30...Connected
128 128
128 128
128 128
128 128
128 128
128 128
128 128
128 170
80 209
63 255
128 255
128 255
128 255
128 255
244 255
255 255
255 250
255 210
255 128
255 128
255 128
255 107
255 5
255 0
255 0
128 0
128 0
41 0
24 0
0 103
0 128
0 128
8 235
77 255
128 255
128 255
128 128
128 128

Next step is to get inerface to the 150A Electronic Speed Control(ESC) working.