OBD MPGuino gauge

[n8thegr8]

ok, so I got a serial adapter finally, and started testing my code. The function for converting the hex commands to binary works beautifully, while the function for converting the binary values returned into decimal worked, but the values were off by an order of magnitude, and in reviewing the algorithm, I realized it was stupid, lol. I'll iron that out at work tomorrow, and then once that's tested and working, I can throw it in my car and see if it can talk.

EDIT: got the binary to decimal conversion working as well now, I'm going to try to test it in my car tonight after I get back from the gym to see what I get

[tom43571]

I hooked it up today and tried it. LED 13 flickered and then it powerd up. The only thing to display on the screen are several pixels in the bottom right of the 16x2 LCD. The differenced between my obdguino and the schematic are that I used a 511 ohm resistor (only thing I could find) instead of a 510 and a 2n3904 (had one handy) instead of a 2n3906. If any of this would make the difference let me know and I will go to radio shack.

[tom43571]

I loaded the code from r24 with the LCD4bit library and the display lit up the entire bottom row rather than just the bottom right corner. This time the backlight did not come on.

[tom43571]

I uploaded the mpgguino code and it displays perfectly when plugged into the wall and the OBD so I know I have all of my wiring correct. I dont know if any of this helps but I think I am the only one that has it going and I just want to let everyone know what it is doing.

[cmags]

I've got a working MPGuino, and when I uploaded the OBDuino rev 32 code I got this exact same thing:


(Except that you have the LCD upside down in this pic

Gotta be something in the initialization code. Did you see that dcb updated his initialization code w/ Yoshi's suggestion for his v0.67? Maybe that's worth a shot. I'll read through the code later to see if anything stands out.

This definitely doesn't have to do with the 511ohm vs 510ohm resistor. Where do you see that its 511ohms? Did you measure that? Because the gold stripe on the resistor indicates 5% tolerance (+/- 25ohms), so you most likely have a 510ohm resistor that's actually quite w/in spec. 510ohm should be green-brown-brown (51 * 10^1).

The difference between a 2n3904 and 2n3906, however, is a big one. The 3904 is an NPN transistor, and the 3906 is PNP. These run in reverse polarity to eachother, so I would change that out for the correct one.

[tom43571]

Originally Posted by cmags

I've got a working MPGuino, and when I uploaded the OBDuino rev 32 code I got this exact same thing:
(Except that you have the LCD upside down in this pic

Gotta be something in the initialization code. Did you see that dcb updated his initialization code w/ Yoshi's suggestion for his v0.67? Maybe that's worth a shot. I'll read through the code later to see if anything stands out.

I saw that he updated the mpguino code and I loaded it onto my obdguino. It looks great especially the large instant MPG. I didnt realize that the LCD was upside down until I finally got some words to display.

[n8thegr8]

Originally Posted by tom43571

I saw that he updated the mpguino code and I loaded it onto my obdguino. It looks great especially the large instant MPG. I didnt realize that the LCD was upside down until I finally got some words to display.

so do you have it reading the data from the OBDII port correctly? or are you just trying to get the lcd working? because that would be awesome if you had it working! I'm still wiring on a male serial port onto my arduino to hook up with my already built cable, so no test tonight, tomorrow for sure though!

[tom43571]

I was just trying to be sure the LCD was working properly. The LCD works correctly but when the obduino code is loaded, it only displays the picture I had in post 82.

[tom43571]

Originally Posted by cmags

This definitely doesn't have to do with the 511ohm vs 510ohm resistor. Where do you see that its 511ohms? Did you measure that? Because the gold stripe on the resistor indicates 5% tolerance (+/- 25ohms), so you most likely have a 510ohm resistor that's actually quite w/in spec. 510ohm should be green-brown-brown (51 * 10^1).

The difference between a 2n3904 and 2n3906, however, is a big one. The 3904 is an NPN transistor, and the 3906 is PNP. These run in reverse polarity to eachother, so I would change that out for the correct one.

Thanks for the info. I just didnt want to go buy a 2n3906 because I have to buy them in packs of 10 but I will change it out tomorrow. I couldnt find a 510 ohm resistor so I wired a 470 and a 41 in series.

[Magister]

I soldered my freeduino yesterday, I still have to wire the LCD display then I will start testing. I did a copy/paste of the mpguino LCD code and made minor mods to it so I don't know why it does not work :-/

You can plug a laptop on the *duino serial port, set your terminal at 115200 to see what's happening?