MPGuino not timing out / backlight stays on
 

Hi,

I just finished assembling a MPGuino that's using version 0.86 and installed it in my Civic VX. I noticed hours later that the backlight was still on. I tried setting the timeout lower as a test, but it still never turned off.

Everything else including the contrast seems to work fine... Has anyone had this issue? Any suggestions?

Thanks!

Have you been assembling your MPGuino by yourself? Can you dimm the LCD with the middle button? If not there's something wrong with LED power supply.

Give some more details about your build. If you're using Arduino board or single ATmega chip? I'll give you the solution then. But first check if you can dimm your LCD.

I built it with an Arduino. It does cycle through brightness levels 0 - 3 (3 is most dim) when I press the middle button. However... after the brightness level text goes off the screen, it appears to re-brighten back to level 0, no matter what option I pick.

I know what's the issue there... :) You've used PNP transistor instead of NPN transistor to take care of the LCD backlight (or the other way around NPN instead of PNP - depends on the LCD setup). Switch to similar transistor but of different type and your problem will disappear.

Good luck!

Hmm, I followed the circuit here http://ecomodder.com/wiki/images/7/7..._Schematic.GIF that shows a PNP (2N3906) although I used a 2N4403 (somewhat equivalent, also PNP) as it was what I had on hand. Is there a version that uses an NPN instead? I'm using a blue w/ white letter 16x2 standard HD44780 LCD if that makes any difference.

I see... But change it to this:
http://ecomodder.com/forum/attachmen...1&d=1424813418

And it'll solve your issue.

Ok, I swapped it out for an NPN and now brightness 0 is off and 3 is brightest. And it stays the brightness level I pick. I'll hook it back up tomorrow to double check it's working in the car, but the brightness seems to be working properly now.

Thanks for your help!!

I'm glad I could be of help :)

So, did this fix your display never turning off?

I am having the exact same issue.

Thanks.

Yes; switching the transistor fixed this issue for me. Thanks again to AndrzejM for the suggestion!

Now I just have to sort out why the MPG is off :(

Thanks, the next time I take it apart I will switch out transistor types.

Maybe the schematic should be updated on the wiki?

Not a bad idea

Or is the transistor issue the fact that maybe we are using different LCD displays?

I just had one laying around so I used it.

That's because PNP transistor requires different signal than NPN - NPN with zero signal on the base will cut the current and PNP will cut the current with the high setting. That's why LCD was not dimmed but was brightened to the max. To make it work with a PNP transistor you would need to change the code to dimm LCD with the "high" voltage.

Thanks for the input. I will try modifying the code before modifying the hardware.

AndrezejM, thanks! I was able to edit 2 lines in the code.

My brightness now works as it should instead of backwards.

I will report back if the light now turns off after a timeout period.

Which version of the code have you modified? There's at least 4 versions of that... :)

I am not entirely sure.

I will attach it here if you feel so inclined to look at it and fix my dumb dumb editing!

:)

That's a very old version of the code. I'd recommend using code described here: http://ecomodder.com/forum/showthrea...tml#post381830

Thanks for the information. I will check that out!

On a side note, the pre-assembled mpguino I purchased on 3/4/15 is FINALLY scheduled for delivery today. That's the one I will be running.

The one I assembled was mainly to play with it and get some experience dialing it in.

Hopefully the vss fine tuning I have done will apply to the pre-assembled unit!

Thanks for the information. I will check that out!

On a side note, the pre-assembled mpguino I purchased on 3/4/15 is FINALLY scheduled for delivery today. That's the one I will be running.

The one I assembled was mainly to play with it and get some experience dialing it in.

Hopefully the vss fine tuning I have done will apply to the pre-assembled unit!

AndrzejM, thanks for all your help.

I have abandoned my MPGuino that I put together from the Arduino UNO.

The pre-assembled one I ordered a month ago showed up.

I will say that whatever program he loaded on it is 100x nicer than the old version I was running.

This one seems like it's going to be a lot closer to real numbers vs the old one.

The one I bought was from the link below in case anyone else is interested.

Be warned, shipping is the better part of a MONTH from his country to the Seattle area.

I will also advise, when you look at the included harness do NOT assume that red / black is power. You must look at the circuit board to determine where the wires go. It turned out that white / yellow were the ones that needed power. I simply removed the pins from the connector and re-arranged them so that red/black were power.

MPGuino trip computer - MPGuino