Category Archives: evolocity

EVolocity 3 Axis G-Meter

Posted on by

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);
   }
}

EVolocity Innovation Challenge Parking Aids

Posted on by

At evelocity boot camp on the 22nd of March we talked about aids for use in the parking challenge. For example, a Netduino and one or more ultrasonic rangers could be used to measure the distance to obstacles placed around the car park.

In the picture below the LED bar is displaying the distance to the base shield box with each LED segment representing 2cm.
Netduino based Park Distance Control

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

This code is just to illustrate how this could done and should not be used in production

public class Program
{
   private static OutputPort triggerOutput;
   private static InterruptPort echoInterrupt;
   private static long pulseStartTicks;
   private static GroveLedBarGraph distanceBar;
   private const int MillimetersPerBar = 20;

   public static void Main()
   {
      OutputPort distanceCin = new OutputPort(Pins.GPIO_PIN_D8, false);
      OutputPort distanceDin = new OutputPort(Pins.GPIO_PIN_D9, false);

      distanceBar = new GroveLedBarGraph(distanceCin, distanceDin);

      triggerOutput = new OutputPort(Pins.GPIO_PIN_D5, false);
      echoInterrupt = new InterruptPort(Pins.GPIO_PIN_D4,
         true,
         Port.ResistorMode.Disabled,
         Port.InterruptMode.InterruptEdgeBoth);

      echoInterrupt.OnInterrupt += new NativeEventHandler(echoInterruptPort_OnInterrupt);

      Timer distanceUpdate = new Timer(distanceUpdateCallbackProc, null, 0, 500);

      Thread.Sleep(Timeout.Infinite);
   }

   public static void distanceUpdateCallbackProc(object state)
   {
      triggerOutput.Write(false);
      Thread.Sleep(2);
      triggerOutput.Write(true);
      Thread.Sleep(10);
      triggerOutput.Write(false);
      Thread.Sleep(2);
   }

   static void echoInterruptPort_OnInterrupt(uint data1, uint data2, DateTime time)
   {
      long pulseWidthTicks;

      if (data2 == 1) // leading edge, start of pulse
      {
         pulseStartTicks = time.Ticks;
      }
      else
      {
         pulseWidthTicks = time.Ticks - pulseStartTicks;

         long distance = pulseWidthTicks / 58;

         Debug.Print("distance = " + distance.ToString() + "mm");

         uint ledBar = 1;
         ledBar = ledBar <<(int)(distance / MillimetersPerBar );
         distanceBar.setLED(ledBar);
      }
   }
}