Arduino - Torque

I think this is going to be very similar to what Gary is planning to do so. I need to reread that thread again as it's been a couple of weeks.

In my 80 I have the typical set of 3 gauges screwed under the dash and really like having them.
In the 86 I want that info but don't want the physical gauges.

My stereo being a true android head unit can run the app Torque but without the OBDII port it doesn't help much.

I've been looking for ways to go about this and still be 'invisible' - wireless sensors (expensive and battery powered), micro/megasquirt (expensive and overkill) - but nothing really fit the bill. I've kind of shied away from the arduino option for no real reason but earlier this week I stumbled across this . I may be really late to the party but was pretty excited to see this.

Now it seems like Arduino is the way to go. Sadly I know next to nothing about it so will have a lot of questions. There is a good arduino forum but considering the electrical brain power on this forum combined with the knowledge of the application vehicle, I have high hopes that this project is possible.

Here is what I am looking for at this time:

1. Engine coolant temp
2. Oil pressure
3. Transmission temp
4. Transmission temp 2 (GVOD)
5. Voltmeter (optional)

As I said, I don't even know what all will be needed but for a starting point I'd like to nail down the long run wiring.
The reason for this is that I want to install the unit in my console and would like to run the wiring now since I am getting ready to install the console to avoid pulling the seats and lifting the carpet again (ideally). The wiring won't be connected to anything yet - just zip tied out of the way on either end.

Already in the console I have 8 awg power and ground going to a BlueSeas 6 fuse block. Relays can be installed as needed.

This is likely not as simple of an answer as I am thinking it is but for 5 sensors how many runs and of what gauge should I install?

I am thinking I can and want to use standard automotive 2 wire sensors. So does that mean 10 wires need to run back to the arduino? I was told that certain sensors could all run on the same wire and the arduino could identify them by address but I haven't found much info on that.

Gary - if you have already covered this ground or someone else has here, please let me know and I'll do more reading. Right now I am a bit overwhelmed and googled out.

Scott - I'll follow that link in the morning.  But for now, I don't think you want to get into multiplexing sensors on a single wire.  So plan on at least one wire per sender and two, signal and ground, would be better.

And your plans are very similar to mine.  I intend to have the Arduino provide not only everything but the tranny temps, but to have an alarm when one of them is over or under the reading.

So, we need to work together on this.  The Arduino has plenty of power to do all we want it to do.

Thanks Gary. The single wire approach didn't sound too appealing in this case and with the automotive sensors I am not even sure it's an option.
Two wires it is. What awg do you think? Seems like a lot of projects use cat6 for this stuff so while I'd use automotive wire seems like it won't much in the way of size.
The longest run would be to the gvod and if guess that at maybe 15 one way.

Morning.  I've now read the bit about Torque.  If I understand correctly, you run the application called Torque on an Android device and it connects to the Arduino via Bluetooth.  And you connect the sensors to the Arduino.  So basically all you are using Torque for is the display.

As for the senders, most of the gauges in the your truck have one wire and use the engine as the return, with an exception being the fuel tank which should have its own ground wire as the straps don't ground very well.  But those senders are going to a gauge that has no smarts and just uses the current to generate heat, so variations get damped out very easily.  But obviously the Arduino is smart and can read the info from the sender several times per second.  So if there is noise on it the Arduino will get varying results.  But varying results can easily be averaged by the Arduino.

In my case I plan to just tap into the wire from the coolant temp and oil pressure senders and read the voltage, which I think will be nicely damped due to the large current being sent to the gauges.  And battery voltage will be easy as well.

But the tranny temps will require new circuits.  What senders do you plan to use?  You could use stock coolant temp senders, if they read the right range, and use the same approach as the ones for the gauges.  But you'll need a bit stronger voltage regulator for the ICVR.  I think I spec'd two in the write-up, and the larger one should be fine to handle two more senders.

And for that, all you'd need is maybe #16 wire.  One wire per sender, assuming the transmissions are grounded.  But if you are going with another type sender then small coax won't hurt as you'll use the shield as your ground to prevent noise on the wire.  However, the wire size in whatever coax you use will be overkill.  So a Cat 6 will work and give you more capability than you need.  Or two Cat 5's.

Arduino:
I am considering this one: Bluno Mega 2560 - An Arduino Mega 2560 with Bluetooth 4.0
It has enough analog inputs and it would make for a simpler install having the BT already built in

Sensors:
While these are generally GM sensors (TX3 I believe is the standard name), they seem to be easier to find information for than Fords (TX61?) and are just as readily available. These would be for all the temp sensors (coolant, transmission, gvod).

There is a kit that contains:

x1 15326386 - Sensor
x1 12162194 - Metri-Pack 150.2 Keyed Connector
x3 12124076 - 22-20 AWG Terminals
100% Calibration Certified
Thermistor Technology
Typical Voltage Supply: 5V DC
Operating Temperature: -40 C to 135 C
Sensor Body Material: Brass
Hex Size: 18.90 mm (3/4")
Thread Size: 3/8" - 18 NPTF
Sealing Pressure: 145 kPa
Thermal Time Constant: ** 18 to 24 seconds

You are correct about the usage and Torque being a display application.
In my setup I won't have any ICVR's, right? Those are just for mechanical gauges?

Since these are 2 terminal sensors I will be running a power and a ground to each.

Here is where it's going to show that I have no experience with electrical circuits at this level and themistors...

How many amps would one sensor pull (I feel like I am missing something obvious by asking this)?
How do I figure out if I can put all of those on the single 5v pin of the arduino?

The answers to the amps will likely cover this but you lost me a bit on the 16awg and the cat6 as those are very different in the awg of the wires. Let's forget the cat6 and say I will be running normal automotive wire. I can run 16awg but is that needed? Seems like most arduino sensors are running more around the 20awg and smaller wire although length is unknown to me on those. I don't think I'd go smaller than 18 for durability but I am running out of space in my firewall penetration so 18 would be preferable over 16.

I have answers, but since this is your discussion with Gary I'm only replying to say I'm watching the thread intently.

Jim - PLEASE add your answers.

Scott - That Arduino looks good.  One of the many reasons I've not bought an Arduino to play with is that they are evolving rapidly, and new ones like this one come out frequently.  The addition of Bluetooth is a big help.

But, just make sure that if you need daughter boards or modules, like to control lots of current, they are available for that unit.  I doubt you will need daughter boards, but just in case.

As for the kit, is it associated with Arduinos?  Like sold by people that also sell Arduinos?  It looks like it should work fine from what I can see.  But I ask because if it is they might have the tables or code to convert the output to temp.

No, you won't have an ICVR.  The Arduino will provide 5v to send to the "sensor" so it can then read the voltage returned.  But, this reference says "The 5V output pin is good for ~400 mA on USB, ~900 mA when using an external power adapter."  So the total you can draw depends on the source for the Arduino itself.

Do you know the resistance range of the sensors?  You could easily calculate the current.  I=E/R.  You know E=5 so if if you knew the range of R you'd have it.  For instance, a Bullnose sending unit has a range of 12 to 72 ohms.  At full temp the 12 ohms would give you 5/12 = 417 ma.  Obviously you won't want to use many of those, but maybe the Chevy one is a higher resistance?

Which brings us to wire size.  16ga is way overkill, and the WireBarn site shows that even 22ga wire can easily handle .5A for 20 feet.  But the 20 or 22ga wire that might be more appropriate is harder to work with.  So that's your call.

Some places like Sparkfun have all kinds of Arduino, while others like Adafruit lean on Rasberry Pi.
I think both have their merits.
Haven't heard of the Bluetooth board Scott is looking at but see no reason it doesn't meet the standard.

Expansion boards are just that.
All they need is the socket. Beyond that they should pull their own weight.

I'd assume temp sensors are simple thermistors and pressure sensors are either piezo or barometers.
So the board is acting as a comparator. Out - return = x
In this regard current doesn't matter at all, but higher voltage means less current, and less current means smaller wires needed.

Scott, i wouldn't be at all afraid of using 20-22Ga. wire.
Look at the ubiquitous USB cord. They're everywhere, and take plenty of abuse.

Thanks guys!
It appears the Bluno line (3rd party) isn't extremely common based on the google hits but having the BT already combined is really appealing. Especially when wanting to keep the footprint as clean as possible.

That kit is just a generic GM temp sensor so no ties to Arduino.
Have been looking at this
Using the max resistance of 47.5 (at 150C/302F) that puts me at 105mA. At 93C/200F it would be around 24mA.

I found this diagram here

So are those resistors going to drop the current even more (significantly)? I = 5 / 2800 = 1.8mA
2800 being 2200 + 550 + 47.5