MPGuino release one workspace - Page 38 - Fuel Economy, Hypermiling, EcoModding News and Forum

dcb · 06-28-2008, 06:09 PM

Glad the Mrs. is doing ok. It soulds like your display issues are an order of operations thing and not a hardware glitch per-se. Like you might need to bounce the power to the whole unit after you program it. Shouldn't affect in-car operation as long as you adjust your setup so the LCD is powered and connected to the duino before or at the same time the duino is powered up.

So about the metro vss thing, Keep me honest here:

I tried an experiment where I do a bunch of analogReads on the vss pin while at the end of the loop and keep track of the min and max reading each half second.

I was getting min=0 and max=~630 which translates into 0 and 3.08 volts respectively, a solid LOW and HIGH in atmega land if I am not mistaken. So this leads me to believe that we have a 9 volt drop on the 100k resistor and are running 90 microamps through the pin. I don't know if it cares about current or voltage or what, only saw voltage where below .2 is LOW and above .7 is HIGH on an input pin on the datacheet. I also saw that they reccomend max of 50k for a pullup resistor. But our 100k is attached to 12-0 volts, not 5, so there ya go.

I have not seen the behavior on the saturn, but I believe the saturn uses a hall efect->ecu->speedo to make a nice signal the speedo (and we) can use. I believe the metro actually uses a physical switch in the speedometer head. So it may be addressable by adding some debouncing to the vss signal.

To confound (or possibly explain) this, when I ran my "do a bunch of analog reads" trick, I never observed the half speed displayed issue. I am wondering if the analog reads add just enough capacitance to the input signal to clean it up or what?

awillard69 · 06-28-2008, 07:29 PM

Nice work, DCB. I like the variable setup screens, that should save people from having to adjust the variables before compiling. Now, it should just be copy, paste, upload and go!

I need to stuff my circuit monster into an enclosure and install into one of my vehicles, most likely the Jeep. I may need to rework my buttons to make better use of any enclosure, but that should be minor.

cmags · 06-28-2008, 11:27 PM

Quote:

Originally Posted by dcb

Glad the Mrs. is doing ok. It soulds like your display issues are an order of operations thing and not a hardware glitch per-se. Like you might need to bounce the power to the whole unit after you program it. Shouldn't affect in-car operation as long as you adjust your setup so the LCD is powered and connected to the duino before or at the same time the duino is powered up.

Moved reply to LCD thread: http://ecomodder.com/forum/showthrea...html#post39427

dcb · 06-29-2008, 10:29 AM

Thx Awillard

top_down · 06-29-2008, 10:34 AM

Good news, I reprogrammed the MPGuino this morning and my LCD started working again! So if your LCD goes black, try a fresh upload before you start desoldering it!

So now I have my unit with the latest v0.66 and am working through the setup screens. Can anyone remind me what the injector microsecond/gallon number is supposed to be on the Metro? I know it was there in the setup/comments area on v0.64 but I didn't get the number written down anywhere. The default that is loaded in when I upload the program is 0304409714 but I'm remembering the Metro was supposed to be something different.

I'm going to use your new suggestion for VSS pulses per mile: 16408. My tires are 155 80 R12 so that should be within a percent or two. If my math is right the difference between 145 80 R12 and 155 80 R12 should be about 320, but I'll tweak and report on that once I get reasonably close odometer correlation.

Triple checked my VSS connection and am sure that is correct. My injector connection was next to the injector resistor on the yellow wire. I will move it as you suggested to the yellow with stripe wire directly adjacent to the injector - but from what I see in the wiring diagram this simply puts the tap on the other side of the injector solenoid. Would that make a difference?

I wish I could help you more with the Metro speed issue, but I don't have a scope or the knowledge to tell you what's going on there even if I did. I am happy to try any changes you might suggest and report my findings.

"...it may be addressable by adding some debouncing to the vss signal." - Let me know what you think is appropriate and I'll give it a try. Please be specific. I'm very good at soldering but am not a EE!

dcb, as always, thanks for the help and the fine work!!!

dcb · 06-29-2008, 11:15 AM

That's good news!

metro, MicroSec/Gallon = 684968626 maybe

Pulses/2 revs should be 3 (did get an aplha RPM gauge working with that)

SVOboy · 07-01-2008, 02:20 AM

I feel like I'm missing something fundamental. When I go to upload the .66 code from sourceforge I just get errors, such as "error: redefition of 'byte brightness []'"

Thoughts?

dcb · 07-01-2008, 07:41 AM

Did you delete everything before pasting in the new code? I know it sounds like a stupid question but I have to ask.

top_down · 07-01-2008, 10:05 AM

I had the exact same error the first time I tried to upload v0.64. Reset the arduino and keep trying. I can't say I figured out exactly what solved it, but after the fourth try it worked. Make sure you have the right kind of serial cable (if you are using serial). I plugged my arduino right into the serial port to eliminate that possibility.

My unit is back in the car and reporting some reasonable numbers (although I think maybe too optimistic!). I will report back in a week or two after I manage to burn through some gas - that'll take a while as I am not that inclined to drive the car much when it's 111F outside.

I will say that the display is hard to read in bright sunlight and almost impossible to read when it is hot. I have it perched on top of the steering column in the full Arizona sun. I had hoped to mount it up high but may have to rethink that.

Wonderboy · 07-01-2008, 10:48 AM

Hello all! I've been building the MPGuino, and I think I've succeeded in everything so far except the injector leads...

I have a 1993 Corolla 1.8l (7A-FE). Just as a guide for anyone with a similar situation, I had a hard time finding my ECU, and it ended up being under and behind the console, best accessible by taking out the glove box and looking left and down.

Anyway, I've got everything almost ready but when I take the multimeter to the injector when the car is on (not running of course), BOTH of them read 12v. Which one should I choose??? Can anyone help me with this?

Thanks!