MPGuino release one workspace

[Magister]

There is already a wiki at the home project at opengauge - Google Code

[wagonman76]

Well so far so good. Ratshack got my parts in yesterday so last night after cutting wood I got the guino all wired up. Today at lunchtime I got past the administrator stuff and was able to install the USB drivers. I flipped through all the screens and it works perfectly at least on the bench.

I left it running for a couple hours to see if the display would garble (I used my green one) and it stayed fine. But I did notice that some contrast and brightness settings make the display act funny, so I just avoid those settings. There are plenty of good settings to choose from.

Hopefully tonight I can try it in the car. Ill take a pic of what I got so far too. Ive got an idea for a case too.

I do have one question. I notice the protoshield relocates the reset button. Does anyone know which pins to tap into on the board to do that? Id like to put my 4th tact switch off to the side as a reset button, so once it is in the case, if I need to reset it, I wont have to take it apart.

[Yoshi]

The RESET input is pin-1 of ATmega168.
http://webzone.k3.mah.se/k3dacu/ardu.../schematic.gif

Yoshi

[wagonman76]

About the reset, I did see a reset pin. But what does the other side of the switch connect to? Ground?

Heres a pic of what Ive done. I put the switches and components on a thin strip of circuit board that fits down from the display. So the display and buttons up top, and Freeduino on the back. It will be mounted in a plastic case when done.

I wired it into the car tonight. It gives back information, but all wacky. Speed says about 16 mph, when idling in park. Kind of jumps around when driving. I wonder what is supposed to be coming off the VSS wire. Mine works by sending power back to the ECM, so I am picking up pulses on the ground side. Do I need to pick up positive power pulses somehow?

One thing I am thinking may be wrong is that I tapped into the cruise control module because it was easier to get to. It uses the same 4000 pulses/mile as the speedo, but since the cruise is not turned on, it is probably not sending power and making pulses and might be picking up stray signals instead. Since I dont have a working cruise stick right now, I should find my old wire and bridge 2 wires so it is on all the time, then try that.

My injectors work by 2 banks of 3 injectors firing at a time, each grounding through a separate switch in the ECM. So I tapped into one of the wires on the ground side of the injectors. Then I doubled the microseconds/gal value in the guino since I am technically getting only half the fuel pulses. Online sources http://www.nitrostreet.com/injectors.htm say my injectors are 15 lb/hr, so I based that on fuel at 6 lb/gal and did the math for 3 firing at once. Ended up with 480,000,000 microseconds/gal.

My mpg says 99.9 all the time, which does not make sense even if the speed was off by the amount on the display. So something must be fishy.

Also the screen never went garbled or anything. However, every time I would shut off the engine, the buttons would no longer function. But after restarting the car and the unit getting data, they would work again. Unless I either hit reset, or unplugged the power for a second, then they would work again.

Also, I understand the screen is supposed to time out after 7 minutes? Mine never turned off even after like 20 minutes, so I unplugged it and brought it in the house for the night. I havent actually done the math on the default variable though, I figured it would be right.

[dcb]

It sounds like you have your injector connected to the vss pin on the guino for one, let's double check the vehicle interface wiring for starters. If the mph changes when you are parked but rev the engine then this is likely at least one thing that isn't right.

Edit: Is that a bonefide arduino there?

[Yoshi]

Originally Posted by wagonman76

About the reset, I did see a reset pin. But what does the other side of the switch connect to? Ground?

Have you checked the schematic shown at my post?
The S1 is actually the standard reset button connected to ground on the Arduino.

Yoshi

[wagonman76]

Thank you dcb. You wouldnt believe how many times I checked, and still, sure enough, I had the VSS and INJ wires backwards. I switched them and now the data seems to make much more sense. First off it shows zilch for speed, or distance or mpg. That would explain my hunch with the VSS signal. Tomorrow Ill bridge the cruise wires to keep it turned on and see if I get the signal. Accessing the speedo wire will require taking half the dash apart. I went down the road and back about 1/2 mile total. It showed the amount of time the injectors were open and that I used 0.03 gallons which seems like a good start for now.

Edit: I readjusted the microseconds/gal variable back to the 240,000,000 (based on 6 injectors per pulse) and though I dont have a distance reading yet, now the gallons reading seems to be pretty close based on my drive to work after getting gas. .50 gallons used over 16.0 miles in the rain. Perhaps both banks of injectors fire with each pulse even though they are on separate circuits.

Edit: I checked this morning and the buttons do work now after the ignition is turned off. But the display still wont time out even after 1.5 hrs, so I unplugged it and brought it in. Timeout variable is set to the default 420,000,000 microseconds.

But this thing seems to be off to a good start. Your work is amazing, thank you so much for sharing this with us.

Yep thats a pre-made Arduino board under there. Plastic between them to keep them insulated. When in the car, I keep the arduino and display wrapped separately, and all 3 rubberbanded together. Cant wait to make an enclosure.

[wagonman76]

Originally Posted by Yoshi

Have you checked the schematic shown at my post?
The S1 is actually the standard reset button connected to ground on the Arduino.

Yoshi

Thank you Yoshi. I did look at the schematic, but didnt notice that was the reset up there in the corner. For some reason I was thinking the circle where it said reset was the reset button, and I was thinking it needed to be connected to 5v thru a 10 resistor. Guess Ive been looking at too many tactile switches. Im not the best at reading schematics but Im learning.

That makes it a lot easier, only one more wire to run to my front button board.

[wagonman76]

Well so far so good. I hooked up power to the cruise control and it works quite well. For now I think the mpg reading is pretty accurate. I get a lot better idea of how my car uses gas. Also I like how I see hundredths of a gallon and how little things like going to the top of the driveway uses the same as idling over a mile down a hill up to a stop sign. And how I can get 40-50 mpg by just backing off the throttle a tad while still maintaining speed. This is gonna be great going downstate tomorrow. The instant mpg feature alone is worth its weight in gold.

Eventually Ill put it in a project box, but for now I made a case from coroplast and packing tape, and attached some mounting it so it sets right in front of me so I can still see the tach and get to the HVAC. I have attached a pic.

It still does have some issues, like the display never times out, and sometimes the buttons wont do anything unless I reset (even though the display continues to update on whatever screen it is on). I suppose it could be fixed by a small relay connected to a switched with ignition wire that cuts power to the display when the car is off. Also sometimes it shows my speed as a few mph even when I have been stopped for some time. But the mpg goes right to zero after stopping, which is more important. Maybe the speed glitch will be fixed with the new software update that was posted yesterday.

[wagonman76]

First long trip with the mpguino today. I had no issue with button operation freezing up. The only issue is the display not timing out. However the mpguino itself does time out after probably about 7 minutes and resets the "current" reading.

EDIT: I got a datasheet on my display. It says pins 15 and 16 are not used. That would explain why my brightness setting does nothing. The backlight is part of the LCD and is not externally controlled, like a cheapo car stereo. Unless I can change the programming, I wonder if I could just put another 2N3906 transistor thats switched with ignition breaking the 5v line to the display. Or a maybe a small relay.

I was also wondering, are there any known issues of leaving it exposed to the sun all day in a hot car? Or leaving it in a car all weekend at 20 below zero? If so, I thought of putting a 9v battery in parallel, so if I took it out of the car, it would keep its settings.

The distance reading is dead nuts. Actual speed is a few mph less than my speedometer, which I figured anyway since whenever I go past those speed radar signs it always reads a few mph low. But the odometer reading is dead nuts to the tenth of a mile.

The gallons reading I would say is pretty accurate. Yesterday after filling up I drove to work in the rain and came home and got 31.5 mpg. Today there was a fierce wind from the west all day. The full drive down there got me 36.1 mpg, shielded partially from the wind. The freeway portion coming back I could only get 30 mpg, I had no west shielding and was getting blown all over the place. A few miles after the freeway I filled up, with another broken pump with a clogged filter that wouldnt pump fast enough to kick itself off. Filled right up and spilled a few drops, 33.1 mpg total tank according to that. Mpguino reading for todays trip showed 34.0 mpg. Had the pump kicked off correctly I would have come out extremely close with the mpguino. The rest of the way home with partial west wind shielding got me 36.1 mpg again.

My variables seem all good, Im leaving them alone for now. They should also be accurate when I switch the unit to my 6000 wagon this winter, since it uses the same injectors and vss pulses.