Any interest in developing an open source fuel economy gauge/computer?

[MetroMPG]

Fair enough on the open/registration issue.

Any suggestions on splitting this thread / starting new ones to better organize the process? I don't mind acting as "club secretary".

So far we have 5 people who've purchased *duinos, and who have expressed interest in development/testing of some capacity:

dcb
s2man
me
larrydag
Whoops

[Whoops]

My recommendation, at the moment would be to set up a separate thread for the Arduino.

I just finished typing in a far more lengthy answer, but my login timed out and I forgot to make a copy before I refreshed the page, so that's gone.

In any case, here is what I recall and the rest must not have been important.

We could make something initially that was rot gut cheap, using just 3 LED's. What we are principally interested in is whether the ratio of the injector pulse width, relative to the speedometer pulse width, is going up, going down, or within some window, staying the same. This could correspond to the LED's.

Alternatively, we could go down a stand alone, LED or LCD 4 character display with a couple of buttons.

Or, we could just feed the pulse widths of the two inputs out the serial connection, to a device, which could be a Palm, Blackberry or PC. The time would be Arnuio time, but a user interface on any of the three could interpret that and scale it, according to a adjustment from the user.

Greek bable?

[Coyote X]

a 16x4 or 20x4 lcd is not that expensive and can be directly connected to the Arduino. I think we should go ahead and settle on the size of the screen so everyone can get one and start working on building the interface part of the system. Also the number and position of the buttons would be helpful.

The calculation part is pretty easy really, just a few numbers to manipulate. The sensor interface is also pretty simple. The only thing that is going to take some time is making sure the variables don't overflow and getting an easy to use interface figured out.

http://priusdiy.fc2web.com/image/SCHEMA05.jpg is the supermid schematic and what I was thinking of is basically the same but he already has the numbers filled in. Look in the top left for the injector and tach input circuit.

Those 2 inputs and the lcd interface it is pretty much ready to code up and make work.

I already have lots of 20x4 displays and buttons and junk so as soon as I get around to ordering the arduino I will have everything I need to start building a menu system for it. But it will probably be after school is out before I get into it really.

Another output option would be to hook up an analog meter to it. A 10k rpm tach could be driven to show 0-100mpg by driving it with pulses from the controller. A vss based speedometer could be driven to show mpg instead of mph

[s2man]

Originally Posted by dcb

number of high cycles ...total number of cycles, and vss tics

Originally Posted by dcb

another value for the total number of injector pulses (RPM would be nice).

I thought we were sending three values from the controller: 1) VSS pulse count per second (or other interval). 2) Injector pulse count per second. 3) Injector pulse width. Which cycles are you referring to? Though stored in the controller as two or three byte binary numbers, data will be sent as characters, one byte each, via serial communication.

Gathering these data will use all of three our timer/counters. I figure the high-resolution timer should be used for pulse width & counting. The second for counting the VSS pulses. And the third for our one-second timer. This will preclude any future pulse width modulation output. (But we've still got the analog outputs available, Coyote )

On threads: yes, separate threads for Arduino, code, i/o, palm, etc.

@ Coyote. Thanks for the supermid schematic. I"ll copy the injector input layout (as soon as I figure out what a 2SA1015 is ). I don't think we need tach input though, we need VSS. Is that what he is referring to by 'tach'? You've got LCD experience, I say you pick one and let us know the part number.

On RS232 vs USB. I still don't see the issue. It seems the early 'Palm serial ports' used TTL. (Cables are available for both USB and RS232 to Palm serial). Later Palms used RS232. And even newer ones use USB. TTL, RS232 and USB are all serial; Just get an adapter cable. dbc, can you confirm the Palm ports?

I got my Arduino Saturday. I did my 'hello world' that evening via both blinky light and output to my laptop. Sunday I soldered up my protoype shield and read up on timer/counters. I've been busy with a visiting mother in law since then , and now I'm getting ready for a river clean up this weekend. Shoot. I had hoped to have some input counting coded this week.

[diesel_john]

Just to try and help any way i can.


The VSS signal on '90's Ford is 132 Hz @ 60 MPH
voltage 1.5 to 5.5
resistance 190 to 240 ohms

the injector fires every 2 engine revolutions, grounded by the EEC(Ford)
so injector pulse X 2 is rev's

the injector pulse varies from idle @ 3ms.(car)
to 17ms.(truck) @ 55MPH
resistance 11 to 18 ohms

does not include throttle body injection,
peak hold injection,or
early flex fuel with extra cold start injector.

[larrydag]

I have my Freeguino up and running now. At least it is blinking at me. I built the USB version. I'll probably build the serial version in the middle of next week.

A couple of notes when building the freeguino.

1. LED's have polarity. I destroyed one LED because of this. Make sure the positive (long side) goes into the bottom hole if looking at the Freeduino board. You can orient the Freeduino board if you see the word "Freeduino" right side up and the USB port is on the left. LED's are diodes which need to be oriented in the correct direction.

2. The freeduino assembly forgets to include C1 and C9 in the instructions.

3. When soldering the female headers tack one pin first then complete the rest of the pins. The tack will put the headers in place so you can quickly solder the rest of the pins. It is crucial to make sure they are aligned. Tacking the first pin will help with the alignment.

[Chris D.]

I'd like to request it also be enabled to play the game "Pong"

[dcb]

I assume you've seen this:
http://www.arduino.cc/cgi-bin/yabb2/...num=1187659197

[Chris D.]

[larrydag]

Originally Posted by Chris D.

I'd like to request it also be enabled to play the game "Pong"

Forget pong. I want full heads-up display on the driver side window that shows MPG, SPEEDO, COMPASS, TACH, and ODOMETER. Now that would be slick. Also to include a target acquisition system for those gas guzzlers in my way of P&G'ing.