netNF Electric Longboard Part 1

Wiichuck connectivity

Roughly four years ago I build myself an electric longboard as summer transport. It initially had a controller built with a devDuino V2.2 which after a while I “upgraded” to a GHI Electronics .NET Microframework device.

Configuring the original netMF based longboard

Now that GHI Electronics no longer supports the FEZ Panda III I figured upgrading to a device that runs the nanoFramework would be a good compromise.

I control the speed of the longboard with a generic wireless wii nunchuk. So my first project is porting the .NET Micro Framework Toolbox code to the nanoFramework.

wireless controller test rig

My test rig uses (prices as at Aug 2020) the following parts

  • Netduino 3 Wifi
  • Grove-Base Shield V2.0 for Arduino USD4.45
  • Grove-Universal 4 Pin Bucked 5cm cable(5 PCs Pack) USD1.90
  • Grove-Nunchuck USD2.90
  • Generic wireless WII nunchuk

My changes were mainly related to the Inter Integrated Circuit(I2C) configuration and the reading+writing of registers.

/// <summary>
/// Initialises a new Wii Nunchuk
/// </summary>
/// <param name="busId">The unique identifier of the I²C to use.</param>
/// <param name="slaveAddress">The I²C address</param>
/// <param name="busSpeed">The bus speed, an enumeration that defaults to StandardMode</param>
/// <param name="sharingMode">The sharing mode, an enumeration that defaults to Shared.</param>
public WiiNunchuk(string busId, ushort slaveAddress = 0x52, I2cBusSpeed busSpeed = I2cBusSpeed.StandardMode, I2cSharingMode sharingMode = I2cSharingMode.Shared)
   {
      I2cTransferResult result;

      // This initialisation routine seems to work. I got it at http://wiibrew.org/wiki/Wiimote/Extension_Controllers#The_New_Way
      Device = I2cDevice.FromId(busId, new I2cConnectionSettings(slaveAddress)
      {
         BusSpeed = busSpeed,
         SharingMode = sharingMode,
      });

      result = Device.WritePartial(new byte[] { 0xf0, 0x55 });
      if (result.Status != I2cTransferStatus.FullTransfer)
      {
         throw new ApplicationException("Something went wrong reading the Nunchuk. Did you use proper pull-up resistors?");
      }

      result = Device.WritePartial(new byte[] { 0xfb, 0x00 });
      if (result.Status != I2cTransferStatus.FullTransfer)
      {
         throw new ApplicationException("Something went wrong reading the Nunchuk. Did you use proper pull-up resistors?");
      }

      this.Device.Write(new byte[] { 0xf0, 0x55 });
      this.Device.Write(new byte[] { 0xfb, 0x00 });
   }

   /// <summary>
   /// Reads all data from the nunchuk
   /// </summary>
   public void Read()
   {
      byte[] WaitWriteBuffer = { 0 };
      I2cTransferResult result;

      result = Device.WritePartial(WaitWriteBuffer);
      if (result.Status != I2cTransferStatus.FullTransfer)
      {
         throw new ApplicationException("Something went wrong reading the Nunchuk. Did you use proper pull-up resistors?");
      }

      byte[] ReadBuffer = new byte[6];
      result = Device.ReadPartial(ReadBuffer);
      if (result.Status != I2cTransferStatus.FullTransfer)
      {
         throw new ApplicationException("Something went wrong reading the Nunchuk. Did you use proper pull-up resistors?");
      }

      // Parses data according to http://wiibrew.org/wiki/Wiimote/Extension_Controllers/Nunchuck#Data_Format

      // Analog stick
      this.AnalogStickX = ReadBuffer[0];
      this.AnalogStickY = ReadBuffer[1];

      // Accelerometer
      ushort AX = (ushort)(ReadBuffer[2] << 2);
      ushort AY = (ushort)(ReadBuffer[3] << 2);
      ushort AZ = (ushort)(ReadBuffer[4] << 2);
      AZ += (ushort)((ReadBuffer[5] & 0xc0) >> 6); // 0xc0 = 11000000
      AY += (ushort)((ReadBuffer[5] & 0x30) >> 4); // 0x30 = 00110000
      AX += (ushort)((ReadBuffer[5] & 0x0c) >> 2); // 0x0c = 00001100
      this.AcceleroMeterX = AX;
      this.AcceleroMeterY = AY;
      this.AcceleroMeterZ = AZ;

      // Buttons
      ButtonC = (ReadBuffer[5] & 0x02) != 0x02;    // 0x02 = 00000010
      ButtonZ = (ReadBuffer[5] & 0x01) != 0x01;    // 0x01 = 00000001
}

The nanoFramework code polls for the joystick position and accelerometer values every 100mSec

public class Program
{
   public static void Main()
   {
      Debug.WriteLine("devMobile.Longboard.WiiNunchuckTest starting");
      Debug.WriteLine(I2cDevice.GetDeviceSelector());

      try
      {
         WiiNunchuk nunchuk = new WiiNunchuk("I2C1");

         while (true)
         {
            nunchuk.Read();

            Debug.WriteLine($"JoyX: {nunchuk.AnalogStickX} JoyY:{nunchuk.AnalogStickY} AX:{nunchuk.AcceleroMeterX} AY:{nunchuk.AcceleroMeterY} AZ:{nunchuk.AcceleroMeterZ} BtnC:{nunchuk.ButtonC} BtnZ:{nunchuk.ButtonZ}");

            Thread.Sleep(100);
         }
      }
      catch (Exception ex)
      {
         Debug.WriteLine(ex.Message);
      }
   }
}

The setup to use for the I2C port was determined by looking at the board.h and target_windows_devices_I2C_config.cpp file

//
// Copyright (c) 2018 The nanoFramework project contributors
// See LICENSE file in the project root for full license information.
//

#include <win_dev_i2c_native_target.h>

//////////
// I2C1 //
//////////

// pin configuration for I2C1
// port for SCL pin is: GPIOB
// port for SDA pin is: GPIOB
// SCL pin: is GPIOB_6
// SDA pin: is GPIOB_7
// GPIO alternate pin function is 4 (see alternate function mapping table in device datasheet)
I2C_CONFIG_PINS(1, GPIOB, GPIOB, 6, 7, 4)

Then checking this against the Netduino 3 Wifi schematic.

This image has an empty alt attribute; its file name is netduinoschematic-1.jpg

After some experimentation with how to detect if an I2C read or write had failed the debugging console output began displaying reasonable value

The thread '<No Name>' (0x2) has exited with code 0 (0x0).
devMobile.Longboard.WiiNunchuckTest starting
I2C1
JoyX: 128 JoyY:128 AX:520 AY:508 AZ:708 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:520 AY:504 AZ:716 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:524 AY:508 AZ:716 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:524 AY:536 AZ:708 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:516 AY:528 AZ:724 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:492 AY:524 AZ:720 BtnC:True BtnZ:False
JoyX: 128 JoyY:128 AX:508 AY:528 AZ:700 BtnC:True BtnZ:False
JoyX: 128 JoyY:128 AX:504 AY:532 AZ:716 BtnC:True BtnZ:False
JoyX: 128 JoyY:128 AX:512 AY:532 AZ:724 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:516 AY:532 AZ:712 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:520 AY:532 AZ:708 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:524 AY:532 AZ:708 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:480 AY:504 AZ:688 BtnC:True BtnZ:True
JoyX: 128 JoyY:128 AX:480 AY:520 AZ:728 BtnC:False BtnZ:True
JoyX: 128 JoyY:128 AX:512 AY:520 AZ:704 BtnC:False BtnZ:True
JoyX: 128 JoyY:128 AX:512 AY:548 AZ:708 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:504 AY:516 AZ:728 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:548 AY:536 AZ:704 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:500 AY:528 AZ:728 BtnC:True BtnZ:False
JoyX: 128 JoyY:128 AX:496 AY:524 AZ:716 BtnC:True BtnZ:False
JoyX: 128 JoyY:128 AX:528 AY:536 AZ:696 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:540 AY:540 AZ:720 BtnC:False BtnZ:False
JoyX: 128 JoyY:128 AX:500 AY:520 AZ:684 BtnC:False BtnZ:False
JoyX: 128 JoyY:0 AX:520 AY:508 AZ:696 BtnC:False BtnZ:False
JoyX: 29 JoyY:0 AX:488 AY:576 AZ:716 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:532 AY:540 AZ:700 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:492 AY:512 AZ:708 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:492 AY:516 AZ:708 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:504 AY:512 AZ:708 BtnC:False BtnZ:False
JoyX: 27 JoyY:128 AX:508 AY:520 AZ:700 BtnC:False BtnZ:False
JoyX: 106 JoyY:128 AX:504 AY:516 AZ:700 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:496 AY:520 AZ:700 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:512 AY:532 AZ:716 BtnC:False BtnZ:False
JoyX: 0 JoyY:128 AX:500 AY:516 AZ:708 BtnC:False BtnZ:False
JoyX: 85 JoyY:113 AX:500 AY:536 AZ:720 BtnC:False BtnZ:False
JoyX: 128 JoyY:110 AX:512 AY:532 AZ:712 BtnC:False BtnZ:False
JoyX: 128 JoyY:90 AX:516 AY:528 AZ:716 BtnC:False BtnZ:False
JoyX: 128 JoyY:43 AX:508 AY:468 AZ:660 BtnC:False BtnZ:False
JoyX: 128 JoyY:0 AX:508 AY:532 AZ:712 BtnC:False BtnZ:False
JoyX: 128 JoyY:0 AX:496 AY:524 AZ:716 BtnC:False BtnZ:False

The next test rig will be getting Pulse Width Modulation(PWM) working.

EVolocity 3 Axis G-Meter

A telemetry system could be used to monitor the progress of your electric vehicle and provide feedback to the team & driver about how efficiently/fast it is being driven. As part of a telemetry system lateral, longitudinal, and vertical acceleration could be monitored using a cheap ADXL345 mems accelerometer

Netduino based 3D GMeter

Netduino based 3D G-Meter

Bill of Materials for my engineering proof of concept (Prices as at May 2015)

The sample code reads the acceleration data from the ADXL345 using a driver originally created by Love Electronics. It then displays the magnitude of the scaled acceleration on 3 x LED Bars using code written by Famoury Toure

OutputPort Xcin = new OutputPort(Pins.GPIO_PIN_D0, false);
OutputPort Xdin = new OutputPort(Pins.GPIO_PIN_D1, false);
OutputPort Ycin = new OutputPort(Pins.GPIO_PIN_D3, false);
OutputPort Ydin = new OutputPort(Pins.GPIO_PIN_D4, false);
OutputPort Zcin = new OutputPort(Pins.GPIO_PIN_D5, false);
OutputPort Zdin = new OutputPort(Pins.GPIO_PIN_D6, false);

GroveLedBarGraph Xbar = new GroveLedBarGraph(Xcin, Xdin);
GroveLedBarGraph Ybar = new GroveLedBarGraph(Ycin, Ydin);
GroveLedBarGraph Zbar = new GroveLedBarGraph(Zcin, Zdin);

using (OutputPort i2cPort = new OutputPort(Pins.GPIO_PIN_SDA, true))
{
   i2cPort.Write(false);
}

ADXL345 accel = new ADXL345(0x53);
accel.EnsureConnected();
accel.Range = 2;
accel.FullResolution = true;
accel.EnableMeasurements();
accel.SetDataRate(0x0F);

while (true)
{
   accel.ReadAllAxis();

   uint xValue = (uint)(((accel.ScaledXAxisG / 1.0 ) + 1.0) * 5.0) ;
   uint xbar = 1;
   xbar = xbar << (int)xValue;
   Xbar.setLED(xbar);

   uint yValue = (uint)(((accel.ScaledYAxisG / 1.0) + 1.0) * 5.0);
   uint ybar = 1;
   ybar = ybar << (int)yValue;
   Ybar.setLED(ybar);

   uint zValue = (uint)((-(accel.ScaledZAxisG / 1.0) + 2.0) * 5.0);
   uint zbar = 1;
   zbar = zbar << (int)zValue;
   Zbar.setLED(zbar);

   Thread.Sleep(20);
   }
}

EV Telemetry Demo

At EV Camp in June 2014 I talked about real-time telemetry for the electric carts. This is a demo of how this could be done using a couple of Netduinos, nRF24L01 modules and some other hardware

Telemetry Demo

Accelerometer and Throttle Position Telemetry

Bill of materials (Prices as at July 2014)

  • 2 x Netduino Plus 2 USD60,NZD108 or Netduino 2 USD33,NZD60
  • 2 x Embedded Coolness nRF24L01shields V1.1b + high power modules AUD17.85
  • 2 x Grove Base Shields V2 USD8.90
  • 1 x Grove ADX345 Accelerometer USD9.90
  • 1 x Grove Rotary Angle Sensor USD2.90
  • 1 x Grove 16×2 LCD USD13.90 (Using earlier serial display in pictures)

The mobile device configures the Gralin nRF24L01 library, initialises the Love Electronics ADXL345 Accelerometer library, and creates two timers, one for the throttle position the other for the accelerometer.

_module.OnTransmitFailed += OnSendFailure;
_module.OnTransmitSuccess += OnSendSuccess;
_module.Initialize(SPI.SPI_module.SPI1, Pins.GPIO_PIN_D7, Pins.GPIO_PIN_D3, Pins.GPIO_PIN_D2);
_module.Configure(myAddress, channel);
_module.Enable();

accel.EnsureConnected();
accel.Range = 2;
accel.FullResolution = true;
accel.EnableMeasurements();
accel.SetDataRate(0x0F);

Timer throttlePositionUpdates = new Timer(throttleTimerProc, null, 500, 500);
Timer accelerometerUpdates = new Timer(AccelerometerTimerProc, null, 500, 500);

Thread.Sleep( Timeout.Infinite ) ;

The Accelerometer timer reads the x, y & z accelerations then sends the data as an ASCII string (rather than Unicode) to save space (maximum message length is 32 bytes)

private void AccelerometerTimerProc(object state)
{
accel.ReadAllAxis();
Debug.Print("A- X = " + accel.ScaledXAxisG.ToString("F2") + " Y = " + accel.ScaledYAxisG.ToString("F2") + " Z = " + accel.ScaledZAxisG.ToString("F2"));

_module.SendTo(baseStationAddress, Encoding.UTF8.GetBytes("A " + accel.ScaledXAxisG.ToString("F1") + " " + accel.ScaledYAxisG.ToString("F1") + " " + accel.ScaledZAxisG.ToString("F1")));
}

The base station works in a similar way, configuring the nRF24L01 library then displaying the received messages on the LCD Display.

MPU 6050 Quadcopter IMU has arrived

The  3 x MPU 6050 breakout boards (GY521) I ordered on Alibaba arrived from China yesterday. I’m looking at using a device which has both an accelerometer & gyroscope in one package rather than an IMU assembled from several discrete devices to make the software simpler (only one I2C bus address).

To make the Microsoft I2C implementation work with multiple discrete devices usually requires a layer of abstraction like commonly used AbstractI2CDevice class which I was wanting to avoid in this project.

The test rig for my light weight high performance driver, a netduino 2 plus & breakout board.

Image

If I need a compass to make the Quadcopter controller work I’ll upgrade to an MPU 9150.

I2C read rates on Netduino Plus vs Netduino plus 2

As part of my quadcopter project I purchased a Netduino Plus 2 for the flight controller. The increased performance 48MHz vs. 168MHz CPU and other improvements looked like it could make it possible to implement most or all of the control algorithms in C#.

So I could compare the performance of the I2C interfaces I setup two test rigs which polled an ADXL345 Accelerometer (using the Love Electronics sample code) 10,000 times for X,Y & Z acceleration values.

NetduinoPlusAccelerometer

The different I2C pins on the Netduino plus 2 required some jumper cables

Netduino2PlusAccelerometer

Both devices were running NetMF 4.2 and I monitored the output of the test harness using MF Deploy.

Netduino Plus

22.2797,22.3126,22.3313,22.3129,22.3590,22.3689,22.3497,22.3049,22.3649,22.3836

Average 22.3 seconds roughly 450/sec

Netduino Plus 2

6.8312,6.8059,6.8003,6.8051,6.8319,6.7999,6.8104,6.8194,6.8233,6.8096

Average 6.8 seconds roughly 1470/sec