rando

Well the first part is the type of solution I was thinking about. If you can get the PIC to report the pulse period (either last or average) that should give you good precision. The data rate back to the serial port would then only effect latency rather than latency and precision. In addition to period measurements, an aggregate count would be nice too. That way if you get an error on the serial stream or otherwise let the serial buffer overflow, you'd still have an accurate aggregate count of pulses. That count equates to total distance traveled. The period measurement gives you average speed over the pulse distance.

If you assume we can get some sort of measurement of fuel flow and you'd be able to make a full fledged trip computer (avg and real-time miles per gallon, etc). Woohoo!

__________________
2004 4runner

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DjBac

I have a Viper alarm, but as you mentioned it doen't take the state of the handbrake?
What kind of relays will I need??

DjBac

Any Updates??

Ricky327

What kind of relays will I need??

The standard car relay should do the job.


Any Updates??

Im still working on it. I think the hardware design is setted.

Im still playing around with whats the best way to parse the command as it get received character by character by the relay board.

I will give an update as soon as something is worth mentioning

DjBac

OK!!!
Thanx for the help with the relays!!!

DjBac

Is there any update about the project???

2nau-t

ALREADY BEEN DONE AND WITH USB AND HIGHLY PROGRAMABLE WITH BASIC OR C++
USING <A HREF="http://www.phidgetsusa.com/catalogue.asp">PHIDGETS</A>
FOUND THANKS TO FRODO

chuckctv

use of a basic stamp is actually a great idea,you can have your computer software send a 2 digit code to the stamp everytime it sends a request, this way if the computer locks/malfunctions or even during startup/shutdown, no control over the relays will occur (unless you think theirs a chance when the computer malfunctions it will randomly send the 2 digit request code and then a code reconized to change the relay state; (chances are the same as winning lotto)). so although the stamp concept will increase the cost, it really is a great preventive measure....

chuck

Ricky327

ALREADY BEEN DONE AND WITH USB AND HIGHLY PROGRAMABLE WITH BASIC OR C++


Yes we know they exist

The point of the project is purely for carPC environment.

For examples :

The inputs must take in the dirty 12V with selectable pull-ups/pull-downs. Depending on which part of the car electric its connected to...for example the IGNITION sense require input pull-down while door pins sense require pull-up. Most I/O board take in standard TTL...5V max with no definable pulls.

The ADC must also take up to 12V or more for battery voltage measurements. The voltage range should be adjustable.

The board should be able to drive a standard car relays. Most cant source/sink enough current for this type of relays...some dont even come with a driver.

The board should operate at car battery voltage.

I must say I like the USB on that one though, But its not really designed to be used for car PC unless modified or did I miss something?

DjBac

Phidget's kits are very good!!!
The voltmeters can handle up to 30V...
And the input/output card upt to 30V I think!!!

If I am wrong please correct me!!!!

Ricky327

Having looked at their kits :

http://www.phidgetsusa.com/tutorials...ifferences.asp

The Phidget 8/8/8 Interface Kit

8 Digital Inputs
Switch triggered - The digital inputs require only closing the inputs to the ground terminal via a switch, button, etc. No voltage should be used. The refresh rate is 125Hz for the Digital Input.

It says you only need to short the inputs to the ground. That clearly says all the inputs are pulled up to +5V. It need to be modified if you need to sense if a +5 or +12V is present such as the ignition.

8 Digital Outputs
The digital outputs put out +5V when turned on and 0V when off. The Digital Outputs have a refresh rate of approximately 125Hz.

This board will not drive car relays directly. You will need to add 8 relay driver thats capable of sourcing/sinking 150mA or so.

8 Analog Inputs
The analog inputs receive a voltage between 0 and +5V. The value is converted into a number in the code between 0 and 1000 respectively. The refresh rate on the Analog Input is 65 Hz.

As you said it can take up to 30V...thats probably true or not but the maximum it can measure before saturating is 5V. A voltage divided is needed to scale down the car battery voltage from +12V down to +5V or so.


The Phidget 0/16/16 Interface Kit

16 Digital Inputs
These inputs require that an external voltage source supply the power to input. A voltage of 4 to 30VDC will be read as a high or logical 1, below 3VDC will be read as a low or logical 0. The input is high impedance which means the current will be limited. The refresh rate is 125Hz for the Digital Input.

Sourcing a voltage up to +30V is fine for detecting +12V presence in a car. But what if you want to detect a closed door pins where the pins short the input to the ground? Alot of switches in the car tend to short its input to the ground. So again this need to be modified to cater for that.

16 Digital Outputs
These outputs require that an external voltage source supply the power. The outputs can sink up to 30VDC at 2A. This type of output is commonly referred to as "low side switching" The Digital Outputs have a refresh rate of approximately 125Hz.

This is fine as it can drive the relays directly. 2A sinking is over kill just to drive a relay though...all thats needed to drive a standard car relay is about 150-200mA.


The Phidget 0/0/4 Interface Kit

4 Digital Outputs
The 0/0/4 is a slightly different animal. This Interface Kit uses relays for it's outputs allowing it to switch up to 250VAC at 10A or 100VDC at 5A. This Interface Kit could be used in projects that need to turn on/off larger loads; incandescent lights, relays, solenoids, motors, etc.

Only support 4 fixed relays


Im sure I havent missed anything unless Im looking at the wrong page But the point is, none of the kit can work with the car without modifiying them or buying more than one items. As I said the only thing I liked about the kits is that they are all on USB port.

Only if microchip make flash USB PIC, Ill go USB all the way with my design. Unfortunately the USB PIC they have are only OTP. Windowed version of it for developements are not cheap.

But relax...I still dont have any update worth mentioning. Im still discussing some part of the design with another member in here and havent come to a 100% conclusion yet. And I have been away and been busy for the last few weeks. But as promised it will get done soon...very soon I hope

DjBac

I suppose you are right!!
but for voltage measuring there is a sensor (-30V to +30V)...

So I will just have to wait!!!

strandtc

Unless I missed something about the board you are making, since you are using serial as your communications method, you can only use as many boards as you have serial ports.. right? (Unless you plan on hving some sort of inter-board communication)

With Phidgets you can plug in as many devices as needed to complete the project. The 30V sensor is pretty plug and play (I have one.. havn't tested it yet though). And the relay baord uses good sealed relays suitable for automotive use.

I'm open to options, but what I have seen so far is pretty good for just being able to place and order, and have a working board in hand. I don't like the 5V stuff with Phidgets.. but so far its pretty easy to integrate with 12V

-Chris

Ricky327

Unless I missed something about the board you are making, since you are using serial as your communications method, you can only use as many boards as you have serial ports.. right?

Thats right. Although not cost effective but a USB-SERIAL converter can be used. This is the reason why I wanted to go USB but unfortunately its not possible for me to do it at this time.

(Unless you plan on hving some sort of inter-board communication)

Thats another idea I have been discussing with another member in here...maybe a plug in board. But then how many relays, inputs, ADC, DAC...etc does one really need? I hope 8 x relays, 8 x inputs and 4 x ADC is more than enough for most application. A DAC maybe useful? I cant think of any application though.

And the relay baord uses good sealed relays suitable for automotive use.

The relays maybe sealed but the board they are mounted on is not? I still like the idea of the relays being off board. It gives the flexibilty of placing the relays closer to the device that need controlling...running a long fat wire into the relayboard and back out again to control a high power device is not a good idea. Ill say keep that fat wire short while the relay control wire can go around the car

The 30V sensor is pretty plug and play (I have one.. havn't tested it yet though).

Please do let us know the results.

DjBac

Phidgets kits (0/16/16) use for outputs switches to the ground!!! what does this mean?? Can this be used for A/C controlling? Maybe with a relay to each switch?

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