I'm not very good a step but step but I'll do my best.
The config is useless for changing copter type, that has to be done in the config file before uploading the firmware with multiwii. This is due to the number of things MW supports and the limits of the low end chips it can run on. So each firmware load has to be customized before being flashed to a board.
Finding config.h in the 2.3 version of MW can be a bit trickier because the code is spread across so many files it's no longer right there in the tabs when you open the sketch in the arduino IDE. However the info in the default MultiWii.ino file does say: "Maybe that tab is not visible in the list at the top, then you must use the drop down list at the right to access that tab." So the info is there if you read...just takes a lot of reading.
Anyway. My best attempt at a step by step assuming you've got the arduino software installed and working:
1) Double click on the MultiWii.ino file - it should have the arduino logo for an icon.
2) At the far right of the tab bar in the Arduino IDE is a little black arrow pointing down. Click on it and scroll down towards the bottom where you should find 'config.h' - select it.
3) Read through the entire config.h file. Don't change anything, just read it at this point. If something confuses you there's more info available in the MW wiki here:
http://www.multiwii.com/wiki/index.php?title=Config.h
4) Once you've read through it and feel you have a good handle on it all give yourself a pat on the back - you earned it!
5) If you got stuck on 3&4 don't panic. 90% of the stuff in there you won't need to mess with. However some of the settings will require knowledge about your specific board. Thankfully however it looks like there is a default setting for your board so that should handle the most difficult bits. If you get overwhelmed take a look at all those other files in the multiwii 2.3 distribution, go ahead scroll through a few there are comments that try to explain what's going on. Crazy huh? Good news is you don't need to mess with any of those! That's all the hard work that's been done for you. So if you start to feel overwhelmed in the config.h file just think of all those others and what the guys maintaining this software deal with - I find it helps make the config.h feel a lot less intimidating having that to compare it to
6) ok, let's dig in. Basically in the config.h line any line starting with a // is a comment and will be ignored/disabled. So what you need to do is go through it line by line and find the options you need for your board and enable them by removing the //. The config.h is broken into several sections as explained at the top:
* 1 - BASIC SETUP - you must select an option in every block.
* this assumes you have 4 channels connected to your board with standard ESCs and servos.
* 2 - COPTER TYPE SPECIFIC OPTIONS - you likely want to check for options for your copter type
* 3 - RC SYSTEM SETUP
* 4 - ALTERNATE CPUs & BOARDS - if you have
* 5 - ALTERNATE SETUP - select alternate RX (SBUS, PPM, etc.), alternate ESC-range, etc. here
* 6 - OPTIONAL FEATURES - enable nice to have features here (FlightModes, LCD, telemetry, battery monitor etc.)
* 7 - TUNING & DEVELOPER - if you know what you are doing; you have been warned
* - (ESCs calibration, Dynamic Motor/Prop Balancing, Diagnostics,Memory savings.....)
* 8 - DEPRECATED - these features will be removed in some future release
More good news. You're probably not going to have to mess with section 5/6/7/8 at all and even section 3/4 will only need minor tweaks, section 1 may not need any and section 2 should just need two lines changed.
Side Note: There are actually two ways to make comments in this file that you'll see. There's the shorthand // which tells the compiler (the compiler is the program that takes this "human readable" code and turns it into code the chips on the board can understand) "everything after this point on this line is a comment and should be ignored". Then there are "block comments" which start with a /* and end with a */ For those they say "Everything between /* and */ should be ignored even if it's on multiple lines.
Now I don't know the details of your RC system so I'm going to assume you're running a simple 4 channel PWM setup for now. This is basically normal 4 channel RX with one wire for each channel. (PPM/CPPM/Sbus/spektrum sat are other options that let you run multiple channels on one wire for cleaner simpler wiring - but I'm assuming you're not using them.) Additional channels really help so you can change flight modes - but we can deal with those later once you're up and running.
Alright were were we...7? Something like that. Let's not stress over the numbers. There are enough numbers in the config.h for all of us so I'll just drop the formality at this point and try to help you through the config.h section by section.
Section 1 Basic Setup:
Hey, here's the bit you're most interested in right at the top. Copter type! The default is quad so the line that says "#define QUADX" is uncommented. But we don't want that. So go ahead and put // in front of it. If you're a stickler for formality then you can use spaces to make sure it lines up with the others. But arduino isn't a stickler for that kind of thing so you can just put the // right at the very beginning and it will have the same effect (and give you a visual clue as to what you changed when you look at this in the future.) But you do want it configured for Tri. So go back up two lines to the line that has " //#define TRI" on it and remove that // at the beginning leaving just " #define TRI"
Phew, we're done all changed for tri now right! Well... It is changed from quad to tri now but we've got to check out the rest of the config to make sure it matches your board and setup. So let's move on to the next section.
Motor minthrottle/maxthrottle/mincommand - these all depend on your ESC's and radio setup, the comments explain it better tan I can but you probably don't need to actually change anything here.
I2C settings. This is the protocol the processor on the MW board uses to talk to it's sensors and there are two things that may need to be changed. Speed I'm fairly sure you should have the "#define I2C_SPEED 400000L" line uncommented for the sensors on your board. If you get a bunch of I2C errors in the config program after flashing...then you may need to change it to 1000000L instead but I'm pretty sure only the old original WMP sensors from an actual Wii motion plus need that setting. The other setting is pullups, and again I don't now the specifics of your board but I'd be pretty shocked if it needed the internal pullups so that line should most likely be commented out. Again if you get a bunch of I2C errors after flashing you may want to try changing that - you won't hurt anything by changing it but trying to fly with a bunch of I2C errors won't work since it's a sign that the processor and the sensors can't talk to each other.
Next is where you set the type of board you have. For yours you want the line "#define HK_MultiWii_328P" uncommented and ALL other options commented. (i.e. only one choice should be uncommented)
The next section is for indepenent sensors. You don't have any. So you can make sure everything in this section is commented out.
Hey that's a whole major section done! Woo Hoo we're 1/8th of the way there! Let's move on to Section 2 "Copter Type"
Go ahead and read through this section but chances are you won't have to change anything. There's an option to use a new experimental PID controller...you don't want that so just leave it set to 1. YAW_DIRECTION isn't actually used anymore so you can ignore that. ONLYARMWHENFLAT is a good one to leave uncommented for safety, it does what it says and prevents you from arming the copter if it's not flat. You can disable it if you want to live dangerously and be able to arm while holding the copter crooked or something crazy like that.
The ARM/DISARM section you should make sure one section is uncommented, ALLOW_ARM_DISARM_VIA_TX_YAW is the most common and means you use zero throttle and full right YAW to arm and zero throttle full left YAW to disarm. You could use the other option and then it's the roll stick instead of the yaw stick if you like to roll that way.
Servos - ok, you're a tri so you've probably got some servos and will probably have to change somethign in this section. Unfortunately I can't help you here as I've yet to do a tri. I have setup a flying wing with MW though and it does have servos and I didn't need to enable anything here. But your tail servo is probably a bit more expensive than my 9g wing servos so you may want to read up on this and set some limits so the board can't try to push your servo too far and break something. Sorry I can't be of more help with this part.
The rest of this section is stuff for gimbals, planes and helis. You're not messing with any of that yet I hope so you can just ignore it or make sure it's all commented out if you really want to. (since it doesn't apply to a multi you don't have to comment out things that uncommented by default...but it doesn't hurt to.)
2 sections down and we're past the hardest parts! Let's tackle section 3 "RC System"
What's this note at the top? " /* note: no need to uncomment something in this section if you use a standard receiver */" Hmm, well I did say I'd be assuming you're runnign a standard 4ch setup with each channel on it's own wire so that's us! Cool, we can skip this entire section! If you're looking to use that DSM port on your board though you'll have a bit of reading to do. Again I don't have your exact board and don't have any spektrum stuff that would apply so I can't really help with that if you're looking to set it up - but the comments are pretty helpful and there's always the multiwii forum.
So...Section 4 "alternate CPUs and Boards". Well, your board counts as a promini since it's using the '328 chip. But you're not flying a hex so the first option doesn't matter, and I said I'm assuming you're not messing with extra channels yet so the Aux2 stuff we can ignore as well. (you may want to come back to it later...but I can't really help you too much since I don't now your board well, the comments/files on HK will be your friend here most likely when you are ready to setup aux channels. At at least for now you will be able to use AUX1 on ch5 if nothing else.)
The rest of Section four you can skip unless you know it applies to you. Halfway there and it just keeps getting easier! Section 5 "Alternate setup" Well...we're not doing anything fancy today so we can actually skip all of this as well and leave it as defaults. Easy Peasy!
Section 6 "Optional Features". Optional eh...sounds like we can skip it! Except...you should make sure "FAILSAFE" is uncommented or risk going through what I did and loosing your multi if your RF link goes crazy. Settings for failsafe are explained fairly well, basically it tells the board what to do if it suddenly stops getting a signal from your TX.
One other optional feature you may want (but probably don't) is DEADBAND if you want a deadband around the center of your sticks. If that's your cup of tea then go for it, but if you don't KNOW that you want it...skip it.
The rest of the optional features are just that "optional" and I'd say get up and flying before you start messing with things like buzzers and voltage monitoring if you're going to try and tackle them.
The rest of the file is all optional and development stuff that you don't need at this point so you can ignore it.
There you go, your config.h is setup! So let's save it "File->Save" or "Ctrl-S"
Now let's connect your board. Actually...you probably should have connected your board before starting arduino so it would be detected. Assuming your reading this before trying it do that. If not then you'll have to exit arduino and re-open the sketch after hooking your board up via USB. Now let's tell Arduino how to find your board. go to "Tools->Board" and select "Arduino Pro or Pro Mini (5v, 16mhz) w/ATmega328" That should be the right choice based on what's on your board...but again I don't that exact board so checking the comments/files on HK may be a good idea. Finally we'll tell Arduino where your board is connected. When you plugged your board in windows should have recognized the FTDI chip on it and set it up as a virtual COM port. If you don't know where it ended up then you can open your device manager and view view a list of COM ports - one should show up as FTDI something or other (or if HK went all out it may show up as a multiwii or hk something or other) Just note what COM port number it's listed as and then go to "Tools->Serial port" in Arduino and select it there. If you're on mac I can't really help you - but a bit of google searching for "ftdi mac arduino" or something similar should get you there. If you're on Linux...well, you probably already got board around step 3 and did it yourself already.
Now all you have to do is hit the button with an arrow pointing to the right and a tooltip saying "Upload" - it should be the second button from the left in the top toolbar right next to the check button. Doing so will first compile your code (same thing the check button does) and as long as you haven't messed anything up it should then upload (or flash) it to your board and report success. If it doesn't - then let me know what the error it gives is and I may need you to share one or more files (likely just config.h) on dropbox or pastebin or something so I can see what you did that's causing the error.
Hope that helps and my tone came across as playful rather than condescending as it really was intended to be playful and not condescending...but that can be easily confused in text so I apologize now if you took it the wrong way.
If you're still stuck keep asking questions. More details about your TX/RX setup would help me give more detailed answers but I can't help too much with board specific questions since I really don't have any experience with your exact board. There aren't a lot of MW users on here so asking on RCGroups or the MultiWii forum may get you more help...but if you don't search first and look to see if the questions have already been answered on those forums you may get some unfriendly responses instead.
