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1  Using Arduino / Sensors / Re: Fuel Pressure Sensor for Vehicle Application on: January 28, 2013, 08:25:44 pm
the simplest solution (I think) would be to use an analog oil pressure sensor

I hadn't thought to use an automotive oil pressure sender... So something like this perhaps?
http://amzn.com/B00029JXMA

This is where I'm rather unsure about how "most" pressure units work. Are they linear output, such that getting a handful of readings from it I can map the rest out pretty easily? Because I'm not finding a spec sheet for it, and I wouldn't really expect to find one for a cheap generic unit like that.

Thoughts? It certainly borders on cheap enough to play around with, but I don't like burning $20s either if someone can tell me that's all I'd be doing smiley
2  Using Arduino / Sensors / Re: Fuel Pressure Sensor for Vehicle Application on: January 25, 2013, 12:27:08 pm
Well when I think of "old cars",   it is not fuel injection that I have in mind.

I guess 3 bars sounds high ,  if you don't have fuel injection,   and it sounds low,  if you do have fuel injection.

For antique 1969 fuel injection,  it probably sounds about right.   

Yeah. The definition of old keeps on changing. While the car is an 89, the body dates to 1984, which means the thing was designed 30 years ago. That's a long time in the automotive world so when choosing between calling it a "new car" or an "old car" I tend to go with the latter, even if it is post many of the seminal car advancements of the last 60 years.

3  Using Arduino / Sensors / Re: Fuel Pressure Sensor for Vehicle Application on: January 24, 2013, 01:32:28 pm
Quote
Thanks guys! Let me know if you think I'm missing any parameters that should be taken into consideration when trying to make this measurement.

Probably the most important property for the pressure sensor you select for your application is it's compatibility with the media it's measuring, gasoline in your case.

 Make no mistake that the required diaphragm isolated barrier is what makes such sensors cost significantly more then the sensors with no such barrier protection for the sensing element. You tend to get what you pay for in this line of sensors.

Lefty

Thanks, Lefty. The Data sheet states
"Chemical Compatibilities:   Any gas or liquid
compatible with 304L & 316L Stainless Steel.  For
example,  Motor Oil, Diesel, Hydraulic fluid, brake fluid,
water, waste water, Hydrogen, Nitrogen, and Air."


So I think I'm good. And it's nice to know what I'm paying for when buying a $100 pressure sensor!
4  Using Arduino / Sensors / Re: Fuel Pressure Sensor for Vehicle Application on: January 23, 2013, 08:45:41 pm
Hey! A Reply! I'll take it smiley

The car is a 1989 BMW 325i, and uses a standard Bosch FPR. and I'm positive that's the correct pressure.

Out of curiosity, do you think it's oddly high, oddly low, or odd that it's measured in Bars? smiley
5  Using Arduino / Sensors / Re: Fuel Pressure Sensor for Vehicle Application on: January 23, 2013, 03:12:50 pm
I wish I knew if the 21 views and no replies means that I'm spot on, or so far out in left field that I'm not worth helping...

Since I can't decide which one it probably is, I'm probably out in left field, aren't I?  smiley-sad
6  Using Arduino / Sensors / Fuel Pressure Sensor for Vehicle Application on: January 21, 2013, 05:06:57 pm
I'm looking for some validation on my choice of products for my intended purpose. I'm a software engineer (UI level) with an old car as a mechanical hobby. Sometimes these two things collide in the middle would of electronics that I know so little about.

Quick explanation of my project: To use my arduino to moitor and log vehicle parameters for the purposes of letting the operator know when those parameters are out of bounds.

My current questions revolve around monitoring the fuel pressure, and the correct pressure sensor to use. I'm trying to come up to speed on the world of sensors and how one describes the sensors, but I could use some help in knowing if my chosen sensor will fit the bill. I try and avoid as many "$90 whoopies!" as I can.

I think I've narrowed it down to the following set of sensor:
http://www.digikey.com/scripts/dksearch/dksus.dll?FV=fff4001e%2Cfff800b3%2C2400035%2C3680003%2C45c009d&vendor=0&mnonly=0&newproducts=0&ptm=0&fid=0&quantity=0&PV252=26

What remains, I am not sure about. For example, for the Arduino and my purpose, which is the ideal output range, 0.5v-4.5v or 1v-5v? How about input voltage? 8v-30v sounds super flexible, but what is the trade off? Any chance that the Hall effect might make a measurable impact on the readings?

The following are all the project parameters that I'm aware of for this particular sensor:
  • Pressure of fuel line 3 bars (43.5psi). High pressure unlikely, mostly detecting low pressure.
  • Under hood sensor location. Need to withstand heat and remain uneffected. However, a cooler location can be chosen so it shouldn't need to withstand anything close to 100C
  • Optional voltage for powering: Varying 12.6v-14v car power Or 5v Arduino output.
  • Accurate to within 5 PSI

And for the sake of argument, let's assume for a second that I know how to blow things up, and not blow things up. Unless someone thinks the sensor will be susceptible to fuel or failure based on the characteristics of the sensor's data sheet, let's start with choosing the sensor and assume I'll be safe smiley

Thanks guys! Let me know if you think I'm missing any parameters that should be taken into consideration when trying to make this measurement.
7  Forum 2005-2010 (read only) / Interfacing / Re: Minicom doesn't pick up serial communication on: May 10, 2010, 01:08:58 am
I'm open to all suggestions and clarifications!

I'm aware that one can't have both the Arduino USB serial AND pin 0 and 1 (tx/rx) active at the same time. That is correct?
That's the reason the code is what it is right now. I don't have an independent power source at the moment, so I need the USB plugged in for power.

But if you mean on the receiving end using the same port, I can assure you it's two different ports, because it's two different hardware devices smiley
8  Forum 2005-2010 (read only) / Interfacing / Re: Minicom doesn't pick up serial communication on: May 09, 2010, 09:22:45 pm
Thanks for the quick reply!

I took a look through the datasheets, and there is some good info in there. However the one other thing besides baud rate that I KNOW is correct is the device/port number.

I'm making a new cable now, just to eliminate that as a potential problem. However I've gone through my breadboard and wires with a multi meter to make sure things are going where I think they should be. Not that it's in the least bit complicated  :-?
And sorry about not using a CODE tag, but I wasn't sure what it is on this board, and out of the half million buttons I don't see one for adding code tags smiley-sad
9  Forum 2005-2010 (read only) / Interfacing / Minicom doesn't pick up serial communication on: May 09, 2010, 08:46:26 pm
Long time lurker, first time being an OP. I've searched high and low for an answer, and I'm finally resorting to any help this gracious community can offer.

I have grand plans in mind, but being new to the Arduino, I'm attempting baby steps. eventually I want the arduino to communicate via the rx/tx lines to my own personal software project. As a first step, I wanted to see if I could get the arduino to send data to minicom, a solid well known cmd line program for serial communication. However even that first step has failed, and I really don't know why.

Here is what is running on the arduino, put there by the 018 IDE running on OSX.

#include <NewSoftSerial.h>

NewSoftSerial mySerial(2, 3);

void setup()  
{

  Serial.begin(4800);
  mySerial.begin(4800);
}

void loop()
{
  Serial.println("Hello, world!");
     mySerial.println("Hello, world?");
     delay(500);
}


Here is what I know:
The USB cable is connected, and the Arduino serial monitor picks up the traffic over the USB cable.
I am wired rx <--> tx and vice-versa
The baud rates are matched on the sending and receiving.
minicom is in a state of "OFFLINE", which has something to do with a DCD line?
The tx LED on the arduino fires repeatedly with the proper delay.

My knowledge of serial communication and minicom are close to nil. It's probably a settings problem, but I can't for the life of me figure it out, or find someone else that has explained it.

Any help out there?
10  Forum 2005-2010 (read only) / Development / Serial Read in Objective C under OSX? on: May 25, 2009, 03:12:40 pm
Greetings everyone!
I'm quite new to the Arduino community, and have only last night gotten one of the sample programs up and running.

I'm in the "Feasibility and Research" part of my project planning, so I have some general questions that google just isn't answering for me. I'm hoping someone around here can.

A tiny bit of background: I'm a recent CS graduate, with little electronic experience, and no real OSX programming experience. As a personal project, I want to read simple analog signals using the Arduino, and pass those signals to my computer as integer values. I would then write a program in Objective C, and be able to read those integer values in and display them.

But before I dive in, what I can not find an answer to, is if it's possible to read in a "serial port" in Objective C/OSX from the Arduino board, while they are connected via USB. The Arduino IDE appears to do just this sort of thing, however since I can find no examples or talk of it on the internet, I'm a bit nervous that what I want to do is impossible, or near enough to it that no one bothers.

Can anyone answer this for me?
Examples/ links to how-tos would be awesome, but unnecessary at this point. Knowing it's possible is what I really care about :-)

Thanks everyone!
~Tyler
11  Forum 2005-2010 (read only) / Interfacing / Re: Connecting Arduino to iPhone/iPod serial on: August 23, 2010, 02:52:39 pm
That would be awesome.  I'll probably work on it too since my project is an educational endeavor. Still, an iPod touch display screen falls into the feature creep category of my project smiley
12  Forum 2005-2010 (read only) / Interfacing / Re: Connecting Arduino to iPhone/iPod serial on: August 22, 2010, 09:37:25 pm
Son of a.... I have the 1.4 breakout, and I was not aware of the manufacturing error. 30 seconds with a soldering iron and I had my iod touch screaming "Hello World!" that was produced by the arduino! Conrad, I could almost kiss you  ;D

Now to figure out how to get at that serial input from ObjectiveC code running on the touch... If you decide to open source that part of your project, I'd be very interested in it. I've never done any sort of port communication in ObjectiveC...or any language for that matter   :-/
13  Forum 2005-2010 (read only) / Interfacing / Re: Connecting Arduino to iPhone/iPod serial on: August 04, 2010, 05:21:29 pm
I used a voltage divider and triple checked it because I don't care to buy a new iPod touch right now ;-)

I don't have the hardware to intercept the arduino tx line and see if there is anything coming out...
This is why I'd love to find someone who has pulled it off. First, it'd show me that it's actually possible, and second, if they shared any piece of their project I could duplicate it on my own and see if it's my hardware that's bad, my code, or my design.
14  Forum 2005-2010 (read only) / Interfacing / Re: Connecting Arduino to iPhone/iPod serial on: August 04, 2010, 05:07:14 pm
I set it all up and got no results.

I did the following:

1. Jailbroke my iPod touch
2. Installed cmd line app to monitor serial comm on the iPod (forget the name now)
3. Connected the tx->rx and vice-versa.
4. Dropped the Arduino voltage down to something the iPod touch could handle (3.3v)
5. Wrote my sketch to spit out serial comm from the Arduino to be read by the iPhone.

Everything appeared to be set up right. Programs ran, no smoke appeared, but nothing showed up on the iPod touch side.

I would be VERY interested to see if anyone has managed to get serial traffic from the Arduino to an iPhone, and what they code looks like. Right now I'm at a total loss for what I am doing wrong (assuming its possible), and I don't even know where to begin trouble shooting since it could be anything at this point.

So does anyone know of a project that has managed this? No Wireless, no 3rd party protocals, no standard play/pause commands, but true serial communication TO the iPod Touch.

15  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Picking a board, newbie help needed on: March 13, 2009, 02:58:43 am
Thank you very much yet again for the info!
Google had yet to find that particular wiki :-)

So this all looks very doable without becoming a(n) EE.
Unless someone cares to contradict my current understanding, or someone else's advice, I guess my only other question is this: Is it programatically, either in Sketch or in whichever computer-side language is chosen, to read in multiple analog signals concurrently? I'm not asking "how", so much as "is it possible with ease". I want to make sure I can get this board to do what I want it to do, without becoming a EE, before I purchase it and sink time into a project. After all, I do still have this darned CS degree to finish ;-)
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