The nanoFrameworkcode polls the wii nunchuk for the joystick position every 100mSec and then updates the PWM duty cycle.
By convention the ESSC PWM frequency is 50Hz (a pulse ever 20mSec) and the duration of the pulse is 1000uSec(minimum throttle) to 2000uSec(maximum throttle), note the change of units.
After converting to the same units there is a pulse every 20mSec and its duration is 1mSec too 2mSec. Then converting the durations to the active duty cycle percentage (for the PWM SetActiveDutyCyclePercentage) the duration of the pulse is 5% to 10%.
I need to re-calibrate the ESC for these durations and ensure that reverse is disabled. Then tinker with the brake (braking percent & percent drag brake) and acceleration(initial acceleration low, medium, high, very high) configurations of my ESC to make the longboard easier to ride.
Next I will look at configurable throttle maps (to make it easier for new and different weight users), then using one of the wii-nunchuk buttons for cruise control (keeping the throttle steady when riding is difficult) and how the software reacts when the connection with nunchuk fails
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.
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.
After some experimentation with how to detect if an I2C read or write had failed the debugging console output began displaying reasonable value
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 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
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.
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 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 ElectronicsFEZ 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.
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
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 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.
Moose 9.5×42 Longboard Flush Mount Deck Green Stain NZ57
Initial trials of the Wireless Nunchuck have not been very positive. As the Netduino device starts the connection to the handset is dropped. Need to do some more investigation to see if I can get this to work otherwise I will have to use a wired Nunchuck.
