View Full Version : New project for getting automotive sensor readings and controlling relays with

11-24-2009, 05:23 AM
I am working on a project to allow for A PC to control a number od relays for automotive switching as well as aquiring data from many automotive type sensors and sending this info via an rs232 connection. My questions are:

Is the BS2 the chip to use or perhaps the propeller, or even another microchip product? The BS2 and Picbasic are the easiest for me to use.

I can easily communicate with the PC with RS232 but could be better for me in .NET to use ethernet. Easy to do ethernet on the chip side?

Should I use nice 12bit A/D chips for the data aquisition of the sensors and pass that to the main chip or just use the internal A/D?

Can I use a standard hardware setup for getting values from resistive type sensors as well as 0-5vdc sensors or do they have to be seperate inputs?

Id like to build the hardware to be as compatiable as possible with many different sensors on the hardware side and just make changes to the software in the PC to handle the rest.



11-24-2009, 05:42 AM
I have read the pulses from the MAF and RPM sensors by tapping into the ECU using a BS2. It is very easy to do

However the BS2 lacks the speed to be able to modify these signals in real time and send them back to the ECU.
Even with a PWMPal the result is the car bouncing all over the place...

So it depends what you are going to do with these signals

11-25-2009, 12:20 AM
I'm actually working slowly on a similar project . Still waiting to get he BS2PX chip and board etc...
But here is where I'm going with it!

Got myself a ELM-327 to read info from CAR Computer. Works great !
Bought a nice ACER one Netbook (no Hard drive, all SSD's) lovely !
Getting all kinds of sensors, GPS, COMPASS etc... got the COMPASS for now... works ok!

Now, getting to program and test some of it on my regular BS2. The PX version is way faster and more options... so can't wait to get my hands on it.. http://forums.parallax.com/images/smilies/wink.gif waiting for a sale from Parallax... hint hint!

Next is to use VB to talk back and forth to the BS2PX (testing with BS2 for now). And also, getting all info from anywhere on the internet on how to talk to the ELM-327 to read speed, load, temp etc... from a VB application.

Then do a nice display using VB and use maybe a 10 inch touch screen, attach to the Netbook.

It's a long project... I got time http://forums.parallax.com/images/smilies/wink.gif
Because I'm way noob in electronics, its longer than its supposed to be...

It is not as much as you are doing, but eventually, we may be able to exchange notes or something!


11-25-2009, 05:43 AM
Try this Demo of Centrafuse. I believe it will read your ELM already and do everything else you want it to do


11-25-2009, 08:26 AM
I will be measuring sensors that are not covered by OBD2 like nitrous bottle pressure, aftermarket fuel system pressure, oil temperature, intake pressure and temperature.

11-25-2009, 08:57 AM
I guess the ELM would not covered everything, but some info in there might be usefull..LOAD , intake temp, engine temp, air intake pressure... just might help.

As for the centrafuse, not sure, I want to design my own compass, altimeter and display some engine info with my own dial... etc...
I'll have a look! So if i could design my own stuff in there,,it would be great !


11-25-2009, 11:12 AM
You need to start making a list of the sensors you want to monitor and what their outputs are and what range you can expect from them. When you have that then you can decide what you want to use to measure them and how.

- Stephen

11-25-2009, 11:58 AM
All of the sensors are either 0-5 volts dc or resistive based, say between 10 and 1k ohms. I figure that seperate ADC's in the 10-12 bit range would be best with I2C output to a processor. The part that always gets be is being accurate when measuring resistance. Would you happen to know of a nice versital chip that measures resistance and splits out a digital value with me having to worry about different resistance ranges?

Thanks for the reply's all!