Automotive HVAC Phidget Interface

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NitroTech

Automotive HVAC Phidget Interface

Postby NitroTech » Tue Nov 11, 2008 7:33 pm

Hello,

I want to explore the application of a Phidget Interfaced to an electronic manual HVAC control head in a vehicle. I'm looking to install a carPC and control HVAC operations. I have a few questions to see if this is possible with this product.

Firstly, an onscreen graphic interface would present user controls for the HVAC selections, would the Phidget accept commands in this manner to perform the function selected?

Secondly, the mode and temperature dials have 9 and 16 positions respectively. These dials are potentiometers. So basically a variable resistor divider changing input voltage to the brain of the HVAC control head. Could a Phidget substitute the input voltages? For example in theory the temp selector with 16 positions inputs voltages based on 5V feed. With an effective working range of 0.1 to 4.9V you would have a .3V change with each position. So .4 - .7 - 1.0 - 1.3 - 1.6V and so on.

Could the Phidget output these voltages on a single circuit to the HVAC control head, of course based on the input from the onscreen interface?

So basically the Phidget Interface would mimic the manual controls. Any help would be appreciated. Thanks.

fitchett
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Postby fitchett » Wed Nov 12, 2008 8:33 am

Regarding the GUI - providing you are able to code the GUI and map what the user is choosing on the functionality provided by Phidgets, then yes, this is no problem. Phidgets are just one part of computer applications written by our users.

On the output side, cars are tricky things to interface with. To replace a potentiometer, you would have to replace it with a isolated digital potentiometer of the same resistance. We do not make a phidget that exposes such a device.

Chester

NitroTech

Postby NitroTech » Wed Nov 12, 2008 11:03 am

For applying the input voltage to the pot(the board), to accomplish this I would physically remove the center pin (wiper)to the board and then apply the required voltage via a circuit from the Phidget. Physical removal of the pot wouldn't be required. Could this be achieved with a Phidget?

fitchett
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Posts: 263
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Postby fitchett » Wed Nov 12, 2008 1:47 pm

We don't recommend it.

Chester


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