A few MPGuino thoughts. - Fuel Economy, Hypermiling, EcoModding News and Forum

spam_bye@yahoo.co.uk · 07-01-2009, 08:12 AM

Hi. Firstly, thanks for a great product... I went for the pre-assembled MPGuino, but replaced the switches and separated the display and the main board (using aluminium foil to protect the components and a hair dryer to melt the hot glue).

The display & switches are mounted in a very slim anodised case above the driver's mirror and the main board is separately mounted behind the dashboard, with a length of ribbon cable between the two parts.

I've just installed this into a 1993 Mazda RX7 (which isn't known for its frugal ways at the pump!) and it works fine. If anyone needs help with their RX7, I can help them find the necessary signals. Please get in touch.

I'd like to fiddle with the code, but there's no USB plug on this board. Would I be able to connect using the unused RX & TX pins, perhaps by RS232? I'd prefer USB, but that's life, eh...

Thanks for reading this far.

Tony

mhopeng · 07-05-2009, 03:51 PM

FYI, the kit from spiffie.org has USB capability. You could buy the same USB interface chip separately and connect it to the RX/TX pins of the ATmega on your prebuilt board.

spam_bye@yahoo.co.uk · 07-08-2009, 09:47 AM

Thanks mhopeng. Don't suppose you know what type IC I'd need, would ya??

Anyway, an interesting thing happened today. The MPGuino completely froze and the only activity on the screen was a flashing cursor block in the top left corner. No response to pulses or switches. Presumably, the code has a little bug somewhere. FYI: The unit was in Instant/Current mode and I wasn't fiddling with it. Incidentally, the CPU reading has been around 654%. Cycling the power fixed the problem.

Flood_of_SYNs · 07-08-2009, 08:02 PM

FTDI FT232R (Something like this)

hu_man · 07-09-2009, 01:34 AM

Spam I am interested in your install of the LCD what kind of case did you use. I have been to every dime store looking for just the right box to mount it in. I like your Idea of putting it above the mirror. I was toying with mounting it on the post but it maybe in the way there.

If you want to really be cheap you can go to the Maxium website and order some 232's for free as demo's. I have done this a few times but do not tell anyone about it.

I do not know about the problem you are having but I would start with the ribbon cable. The unit I have is assembled and it is rock solid. The kit I had was a pain in the ... Good luck and thanks for the tip.
Hugh

spam_bye@yahoo.co.uk · 07-09-2009, 12:42 PM

Thanks for the advice Flood_of_SYNs & hu_man. I'll have a look.

I used a case I found in a local electronics store. I'm in the UK, so it's probably not much use to you. I measured the angle of the windscreen (65deg) and shaved the top of the box to complement, then attached a new top made from the offcut. The top of the case sits perfectly against the windscreen and the case front is vertical. It looks like a factory fit and the ribbon cable is completely hidden under the roof lining.

I'm sure the ribbon cable is 100% and I've used strain relief all the way, so there's no mechanical problem. Anyway, the unit is fine now I've reset the power. When the problem occurred, I was travelling very slowly (0-1mph) and then floored it....MPG registered at 3.15 when the unit froze. The speed was slow and there was a lot of fuel flowing, so I'm pretty certain that something's dividing by 0 and creating the error. I'll have a look at the code when I have time...

Cheers,

Tony