OBD II Driver Improvement Suggestion

Mike · June 5, 2012, 1:40pm

My ODB II module is arriving today, so I began to study the provided driver software.

The driver internals support the selection of English or Metric units for appropriate measurements,
but the OBD_II class, which is the interface to the user, does not allow for changing the
selection from the default, which is English.

It is possible to configure the module for Metric units, by not using the code generated
by the designer, and manually configuring the module constructor after adding a using or two.

I suggest a method/property be added to the OBD_II class for setting the measurement units.

Low priority for me. Others?

Steven_ghielectroncs · June 5, 2012, 1:59pm

We plan on changing the driver quite a bit in the next release to allow users to better use the underlying OBDII class. For now, your best bet would be to just use the OBDII class, that way you have full control over the commands and units.

RorschachUK · June 5, 2012, 2:08pm

Ideally, it might want to be more finely configurable than just a straight choice like that. For instance, here in the UK we have a somewhat confused system whereby we use miles and mph, but we now buy fuel in litres and talk about fuel tank capacities in litres. On the other hand we still most often refer to fuel consumption in miles per gallon even though we’re buying it at the pump in litres. Even more confusingly, the British definition of gallons (the Imperial gallon) differs from the US gallon, it’s about 20% bigger, making it doubly confusing what might be meant by configuring to use ‘English’ units, as I imagine that would mean US gallons and not anything that’s ever been in use in England. So for OBDII-based guages in my car, I would want speed in mph, distances in miles, fuel consumption in mpg (using Imperial gallons) but to enter fuel added to the tank in litres. This is usually possible in OBDII-based car computers available here, although I expect they’re just handling the unit conversions in software from whatever units the hardware’s measuring in.

mhectorgato · June 5, 2012, 2:16pm

I just gave the driver a cursory glance, but I noticed that there seem to be many more PIDs (iirc) than what the driver exposes.

My plan was to extend the driver when I got around to working with this device.

One other suggestion for a future HW rev – could the OBDII be used as a power module as well? If I understood this correctly, then I am assuming that the OBDII port is putting out ~12v :

[quote]/// Gets the battery voltage reading. Note that this value is read
/// directly off the supply pin from the OBD port[/quote]

Mike · June 5, 2012, 2:16pm

Hi Steven:

I think you mean the underlying ElmDriver class?

I am fine with the default English measurements for now. Just wanted to let the PTB know about the absence of an interface at the OBD_II level.

Steven_ghielectroncs · June 5, 2012, 2:33pm

Haha yeah thats what I meant.

dnasitzes · March 12, 2013, 2:01pm

I am trying to connect to the OBD_II module with the Hydra and continuously receive the following error (car is on and sitting in car running program with OBD_II module plugged in).

An unhandled exception of type ‘System.Exception’ occurred in GTM.GHIElectronics.OBD_II.dll

Additional information: Failed to connect to the ELM327

It seems to get caught at this line of code:
obd_II.Connect();

Any suggestions? I’m been stuck on this for a while now with no luck. I might be overlooking something simple (I hope) that maybe someone with experience with this device can share with me.

Steven_ghielectroncs · March 12, 2013, 2:07pm

That error means that the Hydra cannot communicate with the ELM327 chip that is inside the module.

Can you share:
[ul]the code that you are using
how you have the module plugged into your mainboard
how the module is attached to your car[/ul]

dnasitzes · March 12, 2013, 2:17pm

I am connecting the modules as shown below on port 7 of the Hydra. I connected the adapter straight end into the OBD port of the car.
Using this OBD_II module: http://ghielectronics.com/catalog/product/365

Program.Generated.CS

using Gadgeteer;
using GTM = Gadgeteer.Modules;

namespace Hydra_OBD2
{
    public partial class Program : Gadgeteer.Program
    {
        // GTM.Module definitions
        Gadgeteer.Modules.GHIElectronics.LED7C led7c;
        Gadgeteer.Modules.GHIElectronics.UsbClientDP usbClientDP;
        Gadgeteer.Modules.GHIElectronics.OBD_II obd_II;

        public static void Main()
        {
            //Important to initialize the Mainboard first
            Mainboard = new GHIElectronics.Gadgeteer.FEZHydra();			

            Program program = new Program();
            program.InitializeModules();
            program.ProgramStarted();
            program.Run(); // Starts Dispatcher
        }

        private void InitializeModules()
        {   
            // Initialize GTM.Modules and event handlers here.		
            usbClientDP = new GTM.GHIElectronics.UsbClientDP(2);
		
            obd_II = new GTM.GHIElectronics.OBD_II(7);
		
            led7c = new GTM.GHIElectronics.LED7C(14);

        }
    }
}

Program.cs

using System;
using System.Collections;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Presentation;
using Microsoft.SPOT.Presentation.Controls;
using Microsoft.SPOT.Presentation.Media;

using Elm327.Core;

using GT = Gadgeteer;
using GTM = Gadgeteer.Modules;
using Gadgeteer.Modules.GHIElectronics;

namespace Hydra_OBD2
{
    public partial class Program
    {
        String VIN, fuelType, obdProtocol;
        Double fuelLevel, battVolts, ambAirTemp, engCoolTemp, intAirTemp, rpm, throttlePos, speed;

        // This method is run when the mainboard is powered up or reset.   
        void ProgramStarted()
        {
            led7c.SetColor(LED7C.LEDColor.Red);
            Debug.Print("Program Started");
            
            getVehicleData();

        }
        void getVehicleData()
        {
            obd_II.Connect();
            
            bool connect = obd_II.Connected;
            while (connect == false)
            {
                led7c.SetColor(LED7C.LEDColor.Red);
                Thread.Sleep(1000);
                led7c.SetColor(LED7C.LEDColor.White);
                Thread.Sleep(1000);
                connect = obd_II.Connected;
            }
            if (connect == true) led7c.SetColor(LED7C.LEDColor.Green);

            // Debug Printing is Enabled
            obd_II.DebugPrintEnabled = true;

            // Gets ELM357 Version Number
            string elmversid = obd_II.elm.ElmVersionID;

            // Get Initial Parameters
            obd_II.GetAmbientAirTemp();
            obd_II.GetBatteryVoltage();
            obd_II.GetEngineCoolantTemp();
            obd_II.GetFuelLevel();
            obd_II.GetIntakeAirTemp();
            obd_II.GetOBDProtocolType();
            obd_II.GetRPM();
            obd_II.GetThrottlePosition();
            obd_II.GetVehicleFuelType();
            obd_II.GetVehicleSpeed();
            obd_II.GetVIN();
    }
}

Architect · March 12, 2013, 2:19pm

Using code tags will make your post more readable. This can be done in two ways:[ol]
Click the “101010” icon and paste your code between the

 tags or...
Select the code within your post and click the "101010" icon.[/ol]
(Generated by QuickReply)

dnasitzes · March 12, 2013, 2:29pm

I am connecting the modules as shown below on port 7 of the Hydra. I connected the adapter straight end into the OBD port of the car.
Using this OBD_II module: http://ghielectronics.com/catalog/product/365

Program.Generated.CS

using Gadgeteer;
 using GTM = Gadgeteer.Modules;

 namespace Hydra_OBD2
 {
 public partial class Program : Gadgeteer.Program
 {
 // GTM.Module definitions
 Gadgeteer.Modules.GHIElectronics.LED7C led7c;
 Gadgeteer.Modules.GHIElectronics.UsbClientDP usbClientDP;
 Gadgeteer.Modules.GHIElectronics.OBD_II obd_II;

 public static void Main()
 {
 //Important to initialize the Mainboard first
 Mainboard = new GHIElectronics.Gadgeteer.FEZHydra(); 

 Program program = new Program();
 program.InitializeModules();
 program.ProgramStarted();
 program.Run(); // Starts Dispatcher
 }

 private void InitializeModules()
 { 
 // Initialize GTM.Modules and event handlers here. 
 usbClientDP = new GTM.GHIElectronics.UsbClientDP(2);

 obd_II = new GTM.GHIElectronics.OBD_II(7);

 led7c = new GTM.GHIElectronics.LED7C(14);

 }
 }
 }

Program.cs

using System;
 using System.Collections;
 using System.Threading;
 using Microsoft.SPOT;
 using Microsoft.SPOT.Presentation;
 using Microsoft.SPOT.Presentation.Controls;
 using Microsoft.SPOT.Presentation.Media;

 using Elm327.Core;

 using GT = Gadgeteer;
 using GTM = Gadgeteer.Modules;
 using Gadgeteer.Modules.GHIElectronics;

 namespace Hydra_OBD2
 {
 public partial class Program
 {
 String VIN, fuelType, obdProtocol;
 Double fuelLevel, battVolts, ambAirTemp, engCoolTemp, intAirTemp, rpm, throttlePos, speed;

 // This method is run when the mainboard is powered up or reset. 
 void ProgramStarted()
 {
 led7c.SetColor(LED7C.LEDColor.Red);
 Debug.Print("Program Started");

 getVehicleData();

 }
 void getVehicleData()
 {
 obd_II.Connect();

 bool connect = obd_II.Connected;
 while (connect == false)
 {
 led7c.SetColor(LED7C.LEDColor.Red);
 Thread.Sleep(1000);
 led7c.SetColor(LED7C.LEDColor.White);
 Thread.Sleep(1000);
 connect = obd_II.Connected;
 }
 if (connect == true) led7c.SetColor(LED7C.LEDColor.Green);

 // Debug Printing is Enabled
 obd_II.DebugPrintEnabled = true;

 // Gets ELM357 Version Number
 string elmversid = obd_II.elm.ElmVersionID;

 // Get Initial Parameters
 obd_II.GetAmbientAirTemp();
 obd_II.GetBatteryVoltage();
 obd_II.GetEngineCoolantTemp();
 obd_II.GetFuelLevel();
 obd_II.GetIntakeAirTemp();
 obd_II.GetOBDProtocolType();
 obd_II.GetRPM();
 obd_II.GetThrottlePosition();
 obd_II.GetVehicleFuelType();
 obd_II.GetVehicleSpeed();
 obd_II.GetVIN();
 }
 }

Architect: Any prettier? Thanks

Architect · March 12, 2013, 2:37pm