Electric Longboard devDuino V2 Controller

I really wanted to get the longboard working so I had a look at buying Wiiceiver from AustinDavid.com.

The source code is available on Github and I had a spare devicter devDuino Sensor Node V2 sitting on my desk. With some modification (changing pins numbers and removing all references to the second LED) I got the wiiceiver code running on my devDuino.

The Electronic Speed Controller(ESC) and the plastic lunch box (containing the batteries and devDuino) are attached to the deck with 3M Command adhesive strips. The first set of command adhesive strips I tried were for hanging pictures and had a Velcro quick release system. This approach was a failure and the ESC & electronics box fell off after 10-15 minutes use. The Velcro backing tape was getting pulled in the wrong direction so was unable to hold the weight of the electronics when vibration levels increased. I tried them because a “quick release” capability would be handy but I have gone back to using conventional 3M Command adhesive strips and these are working well.

devDuino V2 and ESC on longboard

devDuino based controller interfaced with ESC and wireless WiiChuk

Initial rides went well, though I need to recalibrate the acceleration and braking ramp up/down settings to suit my hardware and riding style.

Bill of Materials for this project (Prices as at Feb 2015)

  • Single Motor Mechanical Electric Longboard Kit USD223
  • Turnigy Aerodrive SK3-6364-245kv Brushless Outrunner Motor USD70.68
  • HobbyKing 150A High Performance Brushless Car ESC USD68.99
  • ZIPPY Flightmax 5000mAh battery X 2 USD31.99 each
  • HXT4mm Battery Harness 14AWG for 2 Packs in Series USD2.43
  • HXT 4mm Gold Connector with Protector (10pcs/set)
  • devDuino Sensor Node V2 USD15.99
  • Grove Nunchuck adaptor USD2.90
  • Grove Branch Cable for Servo USD4.90
  • Wireless Nunchuck NZD25.00
  • Moose 9.5×42 Longboard Flush Mount Deck Green Stain NZD57

WARNING – Disconnect the power supply pin on the Grove Branch Cable for Servos as the ESC will supply sufficient current to make the batteries on the devDuino go pop. Wrap some tape around the other servo connector so it can’t cause a short circuit.

Thanks to Austin David for making the code for the Wiiciever open source, if anyone is interested in my code I can tidy it up and share.

/*
 * Pin IDs -- NOT LOCATIONS !!!
 * don't change these ever; see "pinLocation" below for
 * actual locations
 */
#define RED_LED_ID   0
//#define GREEN_LED_ID 1

#define ESC_PPM_ID   2
//#define ESC2_PPM_ID   6
#define ESC_GROUND 00     // hard-wired

//#define WII_POWER_ID 3
//#define WII_GROUND 00     // hard-wired

#define WII_SCL_ID   4
#define WII_SDA_ID   5

I made my devDuino look like a V3 wiiceiver

int pinLocation(int pinID) {
  int pinMap[7][3] = {
  // v1, v2, v3
    {8,   8,  9},  // RED_LED     any digital pin
    {7,   6,  8},  // GREEN_LED   any digital pin
    {10,  9,  3},  // ESC_PPM     PWM required
    {9,  11,  5},  // WII_POWER   any digital pin
    {19, 19, 19}, // WII_SCL     A5, don't change
    {18, 18, 18}, // WII_SDA     A4, don't change
    {0,  10, 0}, // ESC2_PPM    PWM required
  };

The rest of my changes were commenting out all references to the Green LED as the devDuino only has one onboard LED.

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.

Electric Vehicle Camp 2014-06

The Hardware

The software

Flash an LED

OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
while ( true)
{
   Led.Write(!Led.Read())
   Thread.Sleep(500)
}

Digital Input – Polled

InputPort button = new InputPort(Pins.ONBOARD_SW1, false, Port.ResistorMode.Disabled);
OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
while (true)
{
   led.Write(button.Read());
   Thread.Sleep(1000);
}

Digital Input – Interrupt

static OutputPort interuptled = new OutputPort(Pins.ONBOARD_LED, false);
InterruptPort button = new InterruptPort(Pins.ONBOARD_SW1, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeHigh);
button.OnInterrupt += new NativeEventHandler(button_OnInterrupt);</span></code>

Thread.Sleep(Timeout.Infinite);
static void button_OnInterrupt(uint data1, uint data2, DateTime time)
{
   interuptled.Write(!interuptled.Read());
}

Analog Input

AnalogInput Sensor = new AnalogInput(Cpu.AnalogChannel.ANALOG_0);
while ( true)
{
   Debug.Print( "Value " + Sensor.Read("F2"));
   Thread.Sleep(500)
}

Pulse Width Modulation Output

AnalogInput brightness = new AnalogInput(AnalogChannels.ANALOG_PIN_A0);
PWM led = new PWM(PWMChannels.PWM_PIN_D5, 1000, 0.0, false);

led.Start();

while (true)
{
   Debug.Print("Brightness " + led.DutyCycle.ToString("F2"));
   led.DutyCycle = brightness.Read();
   Thread.Sleep(500);
}
led.Stop();

Telemetry – Mobile station

Configure the NRF24L01 library for the  elecfreaks Joystick ShieldV2.4, for more detail see this post 

_module.OnDataReceived += OnReceive;
_module.OnTransmitFailed += OnSendFailure;
_module.OnTransmitSuccess += OnSendSuccess;
_module.Initialize(SPI.SPI_module.SPI1, Pins.GPIO_PIN_D10, Pins.GPIO_PIN_D9, Pins.GPIO_PIN_D1);
_module.Configure(myAddress, channel);
_module.Enable();

Timer joystickPositionUpdates = new Timer(JoyStickTimerProc, null, 500, 500);
Thread.Sleep( Timeout.Infinite ) ;

Send the data to the base station (converting it from Unicode to ASCII)

private void JoyStickTimerProc(object state)
{
   double xVal = x.Read();
   double yVal = y.Read();
   Debug.Print("X " + xVal.ToString("F1") + " Y &" + yVal.ToString("F1"));

   _module.SendTo(baseStationAddress, Encoding.UTF8.GetBytes( xVal.ToString("F1") + " " + yVal.ToString("F1")));
}

Telemetry – Base Station

Configure the NRF24L01 library for the Embedded Coolness board, for more detail see this post

private readonly NRF24L01Plus _module;

_module.OnDataReceived += OnReceive;
_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();

Display the inbound message (converting it from ASCII to Unicode)

private void OnReceive(byte[] data)
{
string message = new String(Encoding.UTF8.GetChars(data));
Debug.Print("Receive " + message); ;
}