MPGuino release one workspace

[MilesPerTank]

Ok.

Ill update the vss constant to the above posted 4100 and that should take care of my speedo.

[dcb]

Yah, or 4104, close enough, let me know if that works ( it should).

Edit, I must have fixed the double vss issue

Edit #2, I can't say for sure what is going on there just yet, I have 8208 in a geo and it looks pretty solid. Let me know where you land with an accurate VSS.

[dcb]

Update, fixing hanging at 71.5 minutes issue in progress (need to update signal generator too).

[diesel_john]

Originally Posted by dcb

Well I think the 95-98 saturns are afflicted. dieselJohns truck might be, but he put a check valve in the vacuum system and is counting on the 02 sensor to correct maybe? Maybe john can go into detail about the side effects of the check valve, if any.

I am taking off all mods. to the fuel pressure regulator. I was wrong in my hypothesis, the injector based mileage computer works just fine with the stock fuel pressure.

Pics on MAP sensor operation.

[dcb]

Thanks for the update John.



71 minute update: I've updated the code in post 1 and am testing the 70 minute issue on the bench now. It takes a while to debug problems that take 70 minutes to reproduce

update #2, It is still running after 81 minutes so I think we are clear. I'll leave it running (need more guinos).

[dcb]

Tank Raw Data
IJ3440.0uS284920
IC405740VC147544 //display format may overflow, but model is intact.

Tank display
Time 650:57 minutes 78120 loops
Miles 214.86
Gallons 3.79
MPG 56.74
MPH 8.81

Instant Raw Data
IJ000.00uS044064
IC018.00VC027.00 (toggles between 27 and 28)

Instant display
MPH ~20
MPG 41.67


so @ 651 minutes, we have made 78120 1/2 second loops.

Fuel check:
the injector was open for ~ 44064 microseconds per loop
so that is 3442279680 microseconds of open injector time
and we have 3440 seconds displayed in IJ for the trip, close enough!!

Injector count: 78120 * 18 = 1406160, displayed 405740 (assuming leading one isn't displayed), again, close enough. We don't care about injector count except for RPM calculations which we havent tackled yet.

Distance check: 78120 * 27.5 = 2148300, displayed 147544 (assuming leading 2 isn't displayed), again close enough for a quick sanity check like this.

So the data collection logic and the data model appears to be reasonably sound, no? I think the remaining display glitches are a display problem. Note, the tank mph has started creeping up again while typing this.

[dcb]

I don't know if it is a mph clue, but I checked at 1121 minutes and the trip mph was at 0.63 and climbing. 370 miles registered. Everything looks stable (free mem, cpu usage, mpg readings, etc). Signal generator is still generating fine too.

next display glitch: @ 1400 minutes, noticed tank mpg was 4.06, miles 33.21, gal 8.16

[AndrewJ]

Just thought I'd post up to say that my LCD died...

I'll look into the situation tomorrow, luckily I just recived a new freeduino and LCD (to make a second MPGuino) in the mail, so I have another LCD to mess with.

Any suggestions for troubleshooting the LCD? I think it's just the LCD because the 'duino's LED's blink normally when powered up, but the display is blank with the backlight off.

[dcb]

Originally Posted by AndrewJ

Just thought I'd post up to say that my LCD died...

I'll look into the situation tomorrow, luckily I just recived a new freeduino and LCD (to make a second MPGuino) in the mail, so I have another LCD to mess with.

Any suggestions for troubleshooting the LCD? I think it's just the LCD because the 'duino's LED's blink normally when powered up, but the display is blank with the backlight off.

Can you jumper power to the led and see if it still lights up? It could be a common ground, or common power thing, any points in your system that would be a common point of failure for the LCD and backlight? Have you looked at it from all angles in case the contrast got wonked somehow?

Also, are you disconnecting the power or hitting the reset button? The LCD doesn't currently like the reset button and prefers to initialize from a power up (especially annoying in development mode).

Last thing I can think of: have you tried reprogramming the guino? Sometimes the atmel chips gets confused during a brownout and needs to be reprogrammed, occasionally they even need a new bootloader (PITA) so be real deliberate with the power hookup.

If not, see if the new chip works in the old guino. If it does and the old chip doesn't then you can send the old chip to me and I'll see if I can do an autopsy on it and find the cause of death.

Let me know what you find out.

[cmags]

Hey, when powering the 'guino on the bench, what spec power supplies are you guys using? I have a 12v, 200mA supply that happened to fit well and used that for the basic blink tests and such to ensure the 'duino was working, but when I hook up the LCD, blink doesn't even run. So, either my LCD is toasted (its from the parts bin so its possible), or the power supply just doesn't have enough oomph.

[dcb]

Mine is 15V, 500ma. I think the LED backlight alone needs 200ma when on full.

[Yoshi]

Originally Posted by dcb

at some point during the long test, the trip mph dropped to 8.5mph instead of 20mph, probably overflowing, instant is fine.

I checked your numbers and program code.
In the mph() routine, there is one, (vssPulses*3600).

You saw 2,148,300 (vssPulses), then vssPulses*3600=7,733,880,000, which is 0x1CCF9A4C0 in hex. It becomes more than 32bit, or more than the unsigned long range.

Yoshi

[cmags]

Originally Posted by dcb

Mine is 15V, 500ma. I think the LED backlight alone needs 200ma when on full.

Yea, I just ordered new LCDs, because when I plugged in my laptop adapter (16V, 4.5A), it ran the blink test program just fine, but the second I plug in my LCD, the 7508 starts overheating and I have to pull the power within a second or so or things would definitely smoke. Must be a short on the LCD. I'll try to fix it later, but it wasn't backlit anyway so I've got these incoming:

http://cgi.ebay.com/ws/eBayISAPI.dll...m=160247143835

So after that, I should be OK on the hardware. I still need to find that VSS hookup, but I've found a few references to it in my car's wiring diagrams - just need to translate diagram to actual harness location.

I still need to know what information about my injectors I need to know to determine my custom constants in the code. I've read through and found references to specs such as open time and duty cycle and flow rate for the injectors, but I'm quite lost. Is there some newbie information on injectors for determining what I need to know to get this project moving?

[dcb]

FYI, no backlight on those too. I was just checking them out yesterday in fact. You can just point an LED at it I suppose and coat the back of the LED with black paint so it doesn't glare.

The other LCD caveat that paulb gave me was that the temperature range on some LCDs isn't very good. They just go blank below a certain temperature. The "official" one looks like it is 0 deg C ~ +50 deg C per the spec. We might want to reconsider that display before winter gets here. There are a bunch on mouser.com that claim -20 to +70 operating temp for not a lot of money.

[cmags]

Awww, crap. I saw the schematic on the page and it showed the LED+ and LED- so I thought it was backlit. Damn. Maybe I can get him to cancel the order.... thanks for the heads up though.

[dcb]

Sorry dude, the auction was definately misleading, you have a case. They put a schematic up there with LED +- on it.

[MilesPerTank]

I've got a nice 40x4 LCD that is LED back lit. I'm not even going to try to run it off a 7805 unless i can find something much lower than 12V as the input voltage.

I/we should hunt down a decent sized power resister and run it inline with the 7805 in all honesty.

[cmags]

Damn, this is what I got back from the seller:

Hi,

We tried to stop your shipment, unfortunately, the post master left with all of our shipments of the day and from the weekend. On any other day we may have been able to stop shipment, but on Mondays its very difficult to the volume of shipments accumulated from the weekend.

We are sorry that we could not stop the shipment.

O-well, maybe I'll try to get them to send me something discounted... but these will do as test pieces...

@MilesPerTank: I don't see why the 7805 wouldn't work out for your LCD... If you're worried, hook up a dedicated 7805 circuit for your LCD.

[dcb]

The current requirements for a 40x4 backlight are probably 5x that of the nkc LCD, which would put it at the limit of a 1 amp 7805 (and the 2n306 wouldn't handle the current either).

But anyone deviating from the "official" LCD does so at their own risk. Well, it's all at your own risk really but there's lots of variables in LCD land and I aint a sorting all that out for everyone. If you know what you are doing, then that's fine, but there's too much else that needs doing for me to hardly mess with it.

[dcb]

Originally Posted by Yoshi

It becomes more than 32bit, or more than the unsigned long range.

Thanks much for confirming the overflow. Any thoughts you'd be willing to share on the trip vs instant mpg discrepancy? Or better yet, a generic way to multiply and divide 32 bit numbers while not overflowing but retaining max resolution (without a bunch of "if" statements)?