Ok so I have a new issue I'm wondering if anybody has any ideas. Right now I have the netmf board being powered directly off a bec from one the escs. I recently rewired the shield so that the PWM signal now comes directly from the netmf board, instead of the external mcu I was am using to convert the radio PWM into I2C registers. This creates a new problem as netmf takes a couple of seconds to bootstrap and initialize the pwm outputs, and the escs require a 0% signal to bootup properly. I realize that I could solve this by powering the netmf board directly from the battery and power on the escs after the board is initialized, but I prefer to not add extra complexity for powering on the unit. So right now the solution is to power the netmf board on usb to let it bootstrap, then add battery power a couple seconds later to allow the escs to boot properly. Any ideas?

But if I take such a 9dof stick, I must make all the calculations on the .netmf device.
The Razor 9dof would do all this calculations:


I have binary messages over serial: [type:length in byte]

[DIYd:4][ID:1][roll:2[pitch:2][yaw:2][checksum:2] => 13byte

But how to request data on demand? just send a byte to the Razor and respond?

Yeah i would just setup a polling loop to check for an incoming message, then provided the data. and honestly you are providing the data so frequently I dont see any value in doing checksum calculations either.

The reason I don't want to be doing calculations on an external board is it reduces accessibility to the code. Principally we want to be able to plug and play hardware, with all control logic being done on the .netmf device. To be honest if your not gonna use the .netmf device to do your control logic then why use it at all. The additional arduino is for convenience, eventually I would like to move to native solution for handling the radio ppm stuff.

A pull-down resistor on PWM output?

I'm not sure what that would do. The issue is that for the escs to boot they want to see a 0% signal (1000 us pulse, or whatever they have been calibrated for).

Alright guys, I've some new hardware, footage and failure.

Here's the new flight video:
http://www.youtube.com/watch?v=8Dy-4ppzCIM

This is a drastic improvement over the last iteration, and it still involves no native code!

Check out the full post here.

how often does GC kick in?

about every 5 - 7 seconds

I see why you use the Arduino to get the radio data, but why the motors are connected there too? Haven't the Netduino and Domino/Panda native PWM pins? I wanted to use the PWM's on my FEZ.
...
What do you think?

Yeah you noticed that eh? I originally was going to use my arduino as the flight control board. It was just easier to relay motor command over I2C. I actually just finished rewiring the shield so that the pwm pins come from my fez panda directly. So you totally had the right idea there.

So now the razor. Ultimately creating code for interfacing with stuff like the razor is something we want to do, we're just not at that stage yet. Wasting 3ms on parsing the razor's ahrs code is really a waste though, and really from everything i've seen about multicopters so far 50Hz is not gonna be nearly fast enough. You could totally re-write the firmware to get spit out raw data across serial on a demand basis and if you need help i can provide it. My personal recommendation is to just ditch the razor imu for this instead http://www.sparkfun....products/10321.

As far as concetrating all this data on another arduino, I think that adds too much complexity. All I really want the arduino to be is a PPM to I2C converter for the radio. I think eventually I will swap out the teensy for something even smaller.

Cheers

Are there any schematics how to connect the "Dataconcentrator"?
I've taken a deeper look at your framework, it's a good piece of code.

I've added some code to support my peripherals.
I just need an arduino for the Dataconcentrator.

Hey zerov,

I don't have any schematics (it's all just proto'd right now), but at a basic level you will just need to interface your arduino (or any other realtime mcu), and the netmf board over I2C. I used this logic level converter to get them talking: http://www.sparkfun.com/products/8745. It's not actually strictly necessary to use the level converter between the arduino and you netmf board as they are usually 5V tolerant, however since I put the gyro and accel on the same bus you will need the converter(they are 3v only). I will attempt to put together a diagram of how I have everything wired up this weekend.

-Luke

Brandon,

I'm honestly not trying to be pessimistic, I am simply trying to be realistic about the capabilities of NETMF and the hardware at hand. I have a very large amount of experience working with embedded devices and and I also have a very respectable amount of experience implementing, debugging and tuning control loops in autopilot applications.

The thing about quadcopters is that if it fails, it will fail spectacularly, at least resulting in damage to props, probably more. I have actually killed PCBs in quad crashes before due to the intense force involved.

I can certainly understand your enthusiasm in implementing such a system within something that flies, however I may recommend that you practice your EE skills on something that doesn't have the ability to single handedly destroy all hardware involved, not to mention inflict bodily harm (a 12" prop stuck in the wall is not fun...). I'm not saying that you shouldn't do a quadcopter or obey my advice, either, however I would recommend that you seriously consider the limitations of the systems involved.

If you really want to develop autopilot applications in C# .NETMF, I might also recommend that you look into doing it on something like an RC car/boat/hovercraft, etc. All of these are very appropriate for NETMF and I personally have a NETMF powered RC car autopilot project. It's more fun than it sounds and you can always do other stuff like cruise control, etc.

Otherwise, feel free to ignore my advice and proceed. I'm only trying to help

Chris,

I think the point is we alredy are proceeding, I have been flying on .net for the last two days.

So I've been going through the code and got hung up here: PID needs to remain double accuracy Gyro also needs to remain double accuracy I'm not sure how to fix this using AircraftPrinciplaAxes.GetReading() as seperate calls for each axis won't work as you call the Update each time which would result in 3x the I2C calls, same goes for the radio In my implementation the radio is actually an I2C device but in most cases this would be ppm read so native code will need to be added for that lastly in my experience with .net so far I found to minimize the frequency that the GC runs at I minimize the objects that I create during the control loop ie. that AircraftPrinciplaAxes object. It might just be that the size of this project is much bigger than what I was working with but the GC is running 5x as much as it does with FEZiquad but we are basically doing the same thing. also just as a note, i wrote feziquad over the course of the last week, i'm not particularly attached to any of the concepts used I just wanted to fly my damn quad. I really like this style of programming but I am completely unexperienced in this style, just thought you might want to know that before you start letting me muck around...

I would highly writing the control code in native code, and then just calling into it for "command and control" purposes. Basically, the native code does the stabilization and maybe the radio control (so it doesn't go in the wrong direction) but then C# handles the rest.

What is the rest (the part that's not in the control loop)?

Chris

Chris,

You make my point exactly: What is the rest?

If we take the control loop out pretty much nothing and we are looking at Aeroquad ARM. I just wanted to put this out there:

I learned assembly on ARM, I specnt a lot of time in school writing for ARM. Granted I haven't been doing much with that for the last few years, if I truly wanted I could just make Aeroquad ARM version. I think we all need to re-examine our motivation here. For me there is only one reason to program in C#; intellisense. Cheap(free), fast, and good all at the same time(to counter-point my tag line), thats what I want to be able to offer.

I started my quad by working with Aeroquad, then I snapped my arduino in half in a crash. So I decided to try to port to this awesome teensyduino I had laying around. Needless to say that was a chore, after a couple of weeks I gave up. I came up with a new idea, try it on .NET. At the time picked GHI's offering due to the faster processor thinking that would help offset some of the slowness. But that's not the point, the point is I flew one week later. In all my tests so far I have never experienced some sort of instability in .net, granted lots of instability in my control code.

So if you couldn't tell already, my vote is keeping as much as we can in .NET. Drivers are native, drivers are always native. If the firmware is missing something we need (ie reading pulses from the radio), then lets put it in. Edit: (I meant native code in general, possibly Cory's approach) There is only one reason I could write FEZiquad in one week and have it fly, because its .NET.

Anyways I just wanted to get that out there, hopefully we can start off with this goal in mind.

Well, not as good of new as I would hoped, watch around 1:20 for the best performance as of right now. Still not hovering for me but I think I'm having transmitter issues. Anyways as you can tell from the video I wont be flying again for a bit.

i thought we were a bit more stable, we still have some work to do then

I add much more success last night, I've had a few hard crashes so I need to spend some time on the hardware.

Brandon I was just out fishing on my way home, were you able to figure out the issues with your repository I wasn't able to access it last night. It asks me for user name password. I will get to work implementing your methodology, commit when I'm done and maybe put up a video if she flies. Edit: Nevermind i got your PM, smartphones are useful but mostly tedious...