Thread: /hobd - extended OBD2 based trip computer for WinCE/PocketPC/WinMobile/Windows

OK, so I just tested it, if I just choose a COM port it won't connect, but if I choose one of the bt devices that appear in the list (and are the devices I have actually paired with win mobile) then it connects and works fine..

Can you please tell me what is short term fuel economy short?

Another thing I noticed is that if I'm rolling in a gear with throttle off, hobd still shows consumption but in general and in most cars it should be 0 (zero) as the injectors back off and do not spray any more gas into the engine.. Any comments on that?

Also I think I lost the HUD option, the lamda and fuel trims screens.. I only see General and Trip computer in Settings>Screens.. Are they located somewhere else?

Of course you have to choose BT device if you use BT device

Can you please tell me what is short term fuel economy short?

That is what its named after - short term fuel economy.
Thats an MPG calculated using a short time period (couple of seconds) - to show you your instant consumption.

Another thing I noticed is that if I'm rolling in a gear with throttle off, hobd still shows consumption but in general and in most cars it should be 0 (zero) as the injectors back off and do not spray any more gas into the engine.. Any comments on that?

Since hobd reads MAF, all you see is what your vehicle gives to hobd.
This means vehicle's ECU still informs that air is flowing (even if there is no fuel injection).

To support fuel trimming with throttle off a special PID should be used. Some vehicles report it via "PID 03" (A2 Open loop due to engine load OR fuel cut due to deacceleration ).
I don't have any information on how consistent this PID in "wild" so decided not to use it (to avoid possible jerks).

Originally Posted by cail

Of course you have to choose BT device if you use BT device


That is what its named after - short term fuel economy.
Thats an MPG calculated using a short time period (couple of seconds) - to show you your instant consumption.


Since hobd reads MAF, all you see is what your vehicle gives to hobd.
This means vehicle's ECU still informs that air is flowing (even if there is no fuel injection).

To support fuel trimming with throttle off a special PID should be used. Some vehicles report it via "PID 03" (A2 Open loop due to engine load OR fuel cut due to deacceleration ).
I don't have any information on how consistent this PID in "wild" so decided not to use it (to avoid possible jerks).

Yes this PID is usually not supported..

Regarding the COM, BT creates a vitrual port, so even if you choose COM or BT device it should be working, that's why I asked you that..

Short term FC is different from instance from what I saw in your app.. I see you have average, instant and short, that's why I asked what is it.. So probably it is an average of some short period of seconds, that's all I can understand, right? I don't know why you chose this though.. Maybe because the car's trip computer does this as well?

Regarding the COM, BT creates a vitrual port, so even if you choose COM or BT device it should be working, that's why I asked you that..

Right, but hobd needs no virtual port - it can do raw BT.

Short term FC is different from instance from what I saw in your app.. I see you have average, instant and short, that's why I asked what is it.. So probably it is an average of some short period of seconds, that's all I can understand, right? I don't know why you chose this though.. Maybe because the car's trip computer does this as well?

Ah, I've misunderstood your question.
The difference between short and instant fuel consumption sensors is calculation interval. Instant is couple of seconds and short is couple of minutes.
Car's tripcomputers normally has only one value, but having two (or, basically three including the total trip MPG) is very useful (at least for me).

Originally Posted by cail

Right, but hobd needs no virtual port - it can do raw BT.

Oh ok that's cool...

Originally Posted by cail

Right, but hobd needs no virtual port - it can do raw BT.
Ah, I've misunderstood your question.
The difference between short and instant fuel consumption sensors is calculation interval. Instant is couple of seconds and short is couple of minutes.
Car's tripcomputers normally has only one value, but having two (or, basically three including the total trip MPG) is very useful (at least for me).

Yeah actually this is like a smoother presentation of instant mpg I would say.. As it does not have the peaks of instant fc it could be used for assesing the driver's ability to drive in economy mode..

Originally Posted by cail

Right, but hobd needs no virtual port - it can do raw BT.

Does this mean that it only supports a particular Bluetooth chipset?

Originally Posted by Vitaliy

Does this mean that it only supports a particular Bluetooth chipset?

hobd uses .net bluetooth library which knows about MS and widcomm stacks. So its not a chipset, but installed stack matters.
Anyway, as Nitroking correctly noticed, you may always map BT service onto virtual COM port and use that COM port in HOBD for connectivity.

News for justchat_1. I've added a borderless mode into 0.53 build it its now possible to seamlessly integrate HOBD into any frontend app (I've tried OpenMobile and it interacts fine).
Also, as said above, I've made a split and separated non-ui part "hobdcore" into a separate assembly. So it now may be used by thirdparty apps to work with ELM327 in .net code.
The updates could be found on a github.

Originally Posted by cail

News for justchat_1. I've added a borderless mode into 0.53 build it its now possible to seamlessly integrate HOBD into any frontend app (I've tried OpenMobile and it interacts fine).

Thats pretty cool...

Originally Posted by cail

Also, as said above, I've made a split and separated non-ui part "hobdcore" into a separate assembly. So it now may be used by thirdparty apps to work with ELM327 in .net code.
The updates could be found on a github.

but thats great news!!!! One question...how well does your app handle polling? For example, if I wanted to have five controls displaying data at the same time and they all poll data as fast as they can, will your plugin balance the requests and ensure requests only happen as fast as the OBDII device can support?

Originally Posted by justchat_1

Thats pretty cool...
but thats great news!!!! One question...how well does your app handle polling? For example, if I wanted to have five controls displaying data at the same time and they all poll data as fast as they can, will your plugin balance the requests and ensure requests only happen as fast as the OBDII device can support?

HOBD uses a sensor registry concept, where all sensors are managed by a central engine. It normally runs as a separate thread, but can also be manually scheduled. So all sensors reading is scheduled equally by this engine.

I've explicitly tried to reach maximum reading speed (just because primary HOBD's target is slow wince hardware). Beside this hobd supports sensor reading period. This means if you have three fast sensors and one slow (f.e. coolant temperature), it'll read three in a loop and only periodically (say each 20 seconds) will readout fourth (temp).