iDuino MPGuino

[wyatt]

I have been in talks with Kevin at Fundamental Logic for a while. We have talked about the possibility of making a kit specifically for the iDuino MPGuino that would be exceedingly simple to put together (for people like me that really have no background in electrical engineering). You can buy almost everything you need from them, and it is WAY less expensive than going to RadioShack. I opted to use the 8 pin female headers as a way of making the iDuino easily removable should I ever need to. I have spent a lot of time working with the diagram from another thread, so it will be much more "plug and play" for me when everything comes in.

Parts you can get from Fundamental Logic's site:

• 1 iDuino $17.82 for a kit
• 2 5.1v Zener Diode $0.25 each
• 1 1n4004 Diode $0.10 each
• 1 2n3906 PNP Transistor $0.05 each
• 3 6mm Tactile Switch $0.35 each
• 1 470uF 25V Capacitor $0.35 each
• 1 0.1uF Ceramic Capacitor $0.10 each
• 4 8pin Female 0.100" Header $0.45 each

Parts you will need from elsewhere:

• 1 LCD
  16x2 LCD Module While Characters Blue Backlight
  Or a green one from sparkfun or mouser
• 1 220 ohm resistor (RadioShack, 5 for $0.99)
• 2 100K resistors (RadioShack, 5 for $0.99)
• 1 7805 voltage regulator (RadioShack, $1.59)
• Solderable Breadboard (RadioShack, $3.49)
• Wire (free if you can - seriously, watch in parking lots for wire!, $1.00 for phone line or ethernet cable at a dollar store, or new at Wal-Mart or RadioShack)
• 1 Quick-Disconnect (if desired, free from old devices like computers/printers/phones/phone jacks, or $3.99 for a 4 wire quick-disconnect from RadioShack)
• 1 Enclosure (Hobby Lobby, 4 for 1.99)

I stole the original schematic from dcb's thread, so hopefully he doesn't hate me for it! That thread has been going for a lot longer than this one, so it may contain lots of information that people would find useful.


I built my iDuino using the instructions from Fundamental Logic's web site (v2, v3). Then I got it all programmed up, but being a novice I didn't realize that I had to have the 55+ MB file downloaded and ready to go... that took a while! I wound up finding a good page for help on the Arduino. Here is the page for "how to" install the programs on it. Really easy. Here is a link to Post #46 of this thread. cmags does a good job of describing the process for installing the software onto the iDuino.

The iGuino is all wired up in the car. I am currently running v0.71 of the software, and have been able to confirm that it is in working order. Here are picutres of the build.

The basic design I tried to follow. I think I actually switched things around a bit so the 7805 would have it's large metal side facing out (maybe it will reject heat better?).


The board I used from RadioShack, sectioned to match the size of the LCD screen.


I started by soldering the "small things" in place.


I then used the iDuino to keep the 8 pin female headers vertical and soldered it all in place. I had to sand the edges of the female headers to make them able to butt up to each other.


Then I attached the "large components", the 7805 and the large capacitor. I used a 470uF cap, but the recommended is a 330uF.


With everything in place be sure to clip all your leads down close. You don't want them shorting out to each other do you? (correct answer "No.")


I then wired up the screen and the buttons. I used some of the left over board to attach my buttons to, works great.


After attaching my "quick disconnect" (I would really like something better than this cable, it really is quite a pain), I used some string to hold it all together. Here's a couple pictures of how it currently looks.



The whole mess of wires between the display and the iShield will be moved so they connect on the other side. This will save some thickness and allow me to use the large channel that the female headers leave.


Before installing in your car, it may be useful to check out the MPGuino Tests wiki by dcb. He shows different readings you should get between different posts, which may save some significant headaches.

With the wires moved to the other side of the iShield, it is possible to fit the iGuino into a small interlocking storage box! These 3.25" x 1.5" x 1.5" boxes are from Hobby Lobby. It is a tight fit, but perfect for the iGuino!


Here are some more pictures, lots of angles. The clearness of the box could be fixed if you don't like it... mine is held closed with packaging tape, can't even see it.

[cmags]

Sweet, good call with the "shield". I'm planning on an iGuino myself, and have all the parts inbound. I liked the fact that the iDuino is bread-board-able so that means the pins will line up with a solder-board too. I'll be sure to post in here with pics of my progress once I've got all the parts together. Probably sometime next week.

I'm thinking if I do this right, I could triple-stack the boards - iDuino, 'guino' and LCD as plug-in modules and drop the whole thing in a box. Right now my prototype includes a v1.0 Serial Freeduino, and a non-backlit LCD connected by lengths of wire and I'm getting interference issues (I think) on my LCD causing garbage. Hopefully cleaning up the circuits into a single module will help me out here.

[wyatt]

Originally Posted by cmags

I'm planning on an iGuino myself...

That's hilarious! I was going to call the thread iGuino instead of iDuino MPGuino, but I thought it may be confusing to people.

[cmags]

Haha nice. I thought it was an appropriate term. Hopefully we don't get issued a cease-and-desist from Apple for using it.

[SVOboy]

It'll be really nice if they can do something custom for us, eliminate some of the parts scrounging and all that,

[Spiffed]

Hi, I'm Kevin from over at Fundamental Logic.
Here's a quick update on what we've been working on:

The backside (notice the LCD Display is missing ... extrapolate from it's silkscreen)


The front side (notice the large cap is missing, the V+I- header will be a right-angle floppy-power style connector and the connector in the lower right is for an optional FTDI-Cable style connector)


Schematic


Board



To the best of my knowledge, this incorporates all of the original circuitry, plus a MAX232 powered serial interface for code downloads or logging.
The plan is to create a kit containing everything required except the wire and splice connections. (There are export and production restrictions to deal with if the automotive hook-up section is included. Plus the autoparts store is more likely to carry the correct stuff.)

I'm not sure on a price point yet, but I would expect in the $30-40 range.

[dcb]

Hey Kevin, glad you are here. I have been thinking about the packaging quite a bit so hope you don't mind if I consolidate some of those thoughts here.

It looks promising, but I think a ftdi chip (USB) might enjoy a larger audience. My feeling is that I initially underestimated the footprint of legacy free machines out there when this project started.

Another option I'm considering recommending for the DIY PCB version is get an iduino and an extra atmega168 and pcb and do a chip swap AND be left with an iduino to play around with

Or possibly just a kit with the software already loaded (need to wait for more stable software on that one). Pre-Programmed would probably have the largest audience though, and there wouldn't be a "whoops I forgot to spend another $20 on a usb cable" surprise to lay on folks.

The other option that comes up frequently is a shield of some sort, lots of arduino layout boards out there but if there was a board that soldered to the back of a lcd that held the extra components/buttons that an iduino could plug into, that would likely have some appeal.

Last options would be a separate kit (similar to your ftdi adapter) that should cost a lot less than a ftdi cable but have the same pinout. Could also make a rs232 with the same ftdi cable pinout (and a power plug/voltage regulator) so the buyer picks which one they want (assuming they get plenty of warning that they will need one or the other), and it plugs right into the ftdi connector and a usb or serial cable/power adapter.

I've pretty much written off rs232 though, especially since a programming adapter can be improvised with a couple transistors (crib off of serial 1.0).

Buttons, on all my versions I put the buttons in the upper right in the LCD border, so I press down on them, and so there is a left and right and middle. It is a PITA to translate that to a simple PCB though, I wind up making them a bit like making jewelery ( see this post ) but I have a couple things I still want to try in that department. The less profile this has, the better it will work in front of your instrument cluster where you don't have to go looking for it.

The vehicle pins should be as low as possible. Again, this helps with the profile, so you aren't hiding important warning lights or something with your mpg gauge.

LCD, currently trying out some newhaven display ones from mouser. The consensus is that the blue ones suck. The green ones are much better especially if you crank up the contrast. Also keeping temperature performance in mind. Here is the display number I'm currently trying: NHD-0216K1Z-FL-YBW They have less expensive ones from newhaven with the same specs except they have side and bottom pinouts, the side pinouts are a bust, they interfere too much with the vehicle interface location options.

And FWIW, here are the zener part number: 1N4733A-TR (same as radioshack stocks), might matter.

Also, just curious, The Schottky isn't a bad idea, but where'd you get the idea from? Also FYI, I haven't had any trouble with nothing connected to the reset pin for the chipswap versions (left agrnd and avcc alone as well).

The pinout to the buttons and the LCD is the same, correct?

Sorry if it's long winded I'm sure you have thought about a lot of this stuff more than I have. But there it is, open for discussion.

[Yoshi]

It looks very nice PCB.
I would like to recommend to place approx 18 pF capacitors instead of 0.1 uF for C7 and C8.

Yoshi

[wyatt]

Wow, it looks good Kevin! Hopefully dcb and Yoshi's responses will help. I don't know much about electronics, that's why I throw in the "hopefully".
I got all my parts from Kevin in the mail, so I am hoping to put together my MPGuino by this weekend. I think I will breadboard it first to make sure everything is working before I solder things in place. I may be trying the "buttons on the side" thing that Kevin shows in his drawings, and I can move them later if I decide it is taking up too much space... but to be honest, these things are about half the size I expected them to be!

[cmags]

Hey Wyatt, when did you place your order from Kevin? I'm still (eagerly) waiting for my iDuino kit to start my "production" build.

A word of warning: I tried prototyping on a solderless breadboard and had issues with the LCD - turned out to be too much capacitance in the breadboard. After soldering everything together (crappy LCD and big serial Freeduino v1.0), things were working a lot better but still not perfectly. That's probably attributable to the 9" leads from my Freeduino to the LCD.

Definitely try it out via breadboard to get comfortable with the design, but if you run into strange problems, don't immediately assume you were wrong in your build. Took me days on end to figure it out.