Replies to This Discussion

Permalink Reply by andy j on December 6, 2011 at 5:39pm

You are correct!! i read that and realized I mis-spoke with the  180 steps!  the controller would be the bottleneck then at 255 steps (i need to check to see if I can mod the library for more). If it is hardware limited to 255, it could be scaled up.  Its very smooth though. ive tested the servo's a bunch, and it works really well.

Second :  i hope to make it ardupilot compatible,    but for the time being it is simply, as you stated, "an open-source hardware alternative to R/C controller"  (with a few other connections for gps, imu, etc etc hehe)

Hopefully this is what you are looking for!!  Just a controller on one side, an 8-channel receiver on the other, and hopefully up to 40km between the two :-D

Thanks for your interest!!

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Permalink Reply by flynx on December 6, 2011 at 7:27pm

So the PS3 controller outputs 256 steps?  (0-255)

It looks like the arduino PWM output is also 8-bit (256 step).  So there won't be a bottle-neck per say, you will just have 8-bit resolution.  (Or is your arduino limited to reading the PS3 controller at 8-bit?  that could matter later....)

I am frustrated because I spent the last hour trying to look up the resolution of my Futaba radio and couldn't find it anywhere.  The best I could do was an ad for my radio, next to an ad for a more expensive radio with 2048 steps (11-bit resolution).  For now I assume that means my radio is 1024 (10-bit). 

So that means the dreamshield would have a quarter of the resolution of my radio.  (To put that in perspective, it's roughly the difference between standard TV and Blu-Ray.)

Some of the inputs on the arduino were not high enough resolution to read the sensors used on the ardupilot so they incorporated some extra hardware to read the sensors at higher resolution and then send the data to the arduino over serial.  We could do some thing similar......

OK here!  This PWM board is a shield for arduino and gives you 12-bit resolution (4096 steps), that's more than Futaba... and has 32 outputs.  If we use this to drive the servos, we won't have to settle for lower resolution.  This could even be an optional component of the dreamshield.... get a standard 8-bit system or spend a little more for a 12-bit high-res system:

http://www.zagrosrobotics.com/shop/item.aspx?itemid=846

Now... it's not going to do us any good to have 12-bit outputs on the vehicle if we only have 8-bit controller input.  We need to come up with a 12-bit input method too.  I love my PS3 but the joysticks on my futaba are much more precise. 

I love this idea... it single handedly solves about 3 or 4 different problems I have.  I still need to figure out what kind of joystick I would personally prefer.  Keep me updated.  I'm not up to speed on everything you've done yet but once I am let me know if I can help.

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ModeratorPermalink Reply by Graham Dyer on December 6, 2011 at 9:25pm

Personally, (and this is just my preference) I would NOT like to replace my remote (which has basic telemetry BTW) with a PS3 controller or any other controller for that matter, however the long range/telemetry idea is very attractive. Now if my Tx's removable module could be replaced by this "remote" so that I could continue to use it's precision, functions and mixing that would be awesome!

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Permalink Reply by flynx on December 6, 2011 at 10:14pm

The transmitter gimbals are nice but they still use potentiometers.  Optical encoders would be better.  But I see your point, there are many nice features of the R/C controllers on the market.  

These are the reasons I would like an open-source solution:

1)  I am using two 7-channel futabas on the same vehicle.  WAY cheaper than one over-priced 14 channel radio.  But if I had one 32-channel radio, I wouldn't ever have to worry again.

2)  I counted all the transmitters and receivers on one of my vehicles and I got 10.  I need fewer radios.

3)  An open-source long range radio for FPV would almost be nicer than trying to buy one and solder it into an existing radio.

4) I would never have to worry about my PC/TX interface (going both ways).  

5) I honestly think we can make a radio that is better and cheaper than what is on the market.  Expensive radios add junk like color touchscreens and MP3 players.  We can add the important stuff - more channels, longer range, more resolution, better encoders, etc.

I agree I don't want to use a PS3 controller.  I'd like something as good or better than the gimbals in my radio.  But thats the whole point... that it's all user-customizable.

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Permalink Reply by andy j on December 6, 2011 at 10:26pm

Thanks so much for the input!!

I will look up the PWM because I have been looking for another method to do that! I wanted something that wasn't tied up with interrupts like the pwm on arduino.

And as far as using this as a TX module on a standard RC controller, that sounds like awesome capability! then you can use the basic ps3 controller for cheap easy fun,   or your monolith super controller for really fine resolution!

I will begin to look up info on that, but in the mean time, would you be able to tell me if you know the pinout/protocol they use on those? and if its universal? i have a old futaba attack III for a air-boat,   but i think you are at a whole-nother level :-)

Thanks again for all the input! 

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Permalink Reply by flynx on December 6, 2011 at 11:10pm

How are you connecting the PS3 controller to the arduino?  Can you use a USB joystick?  Because many R/C radios have USB adapters so you can connect them to a PC and use them like a joystick.  If that would work, it would prob be the easiest solution.  The signals from the radios are more-or-less the same but not universal, each brand has it's own eccentricity.

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Permalink Reply by andy j on December 7, 2011 at 12:31am

Yes the PS3 interfaces to the board via USB.    And if all the new radios have USB, that would be the easiest way to interface things!

 

 

 

I have added a TSSOP TLC5940  16-output PWM chip with big-time resolution. That is hooked to the arduino via SPI.  There has already been a library or two written for it. 

currently only 8 outputs are being used due to board density.  I may see a way to squeeze another 8 servo connections on there, but im going to hold off for a day or two...   finals are next week !

 

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Permalink Reply by flynx on December 7, 2011 at 2:06pm

Andy, before you get heavy into finals, can you send me a parts list to buy?  I am ready to order two DNT900 radios from Mouser but I guess they don't come with antennas and I'm not 100% sure about the antenna connector. 

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Permalink Reply by andy j on December 7, 2011 at 3:20pm

Its a U.FL on the DNT900 board. I looked on digi-key for a converter, but ended up making mine with a some parts i found in old electronics that i tore apart for parts. You want to convert the female-pinned U.FL  to a male-threaded, female pinned SMA  connector (i believe).

I haven't assembled a master parts list yet.  Is there something (other than the antenna adapter) you're looking for?

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Permalink Reply by flynx on December 7, 2011 at 3:37pm

I guess not.  Just ordered two of everything:

http://www.mouser.com/Search/ProductDetail.aspx?R=DNT900Cvirtualkey...

http://www.mouser.com/Search/ProductDetail.aspx?R=CARSMA-UFL-1virtu...

http://www.mouser.com/Search/ProductDetail.aspx?R=A09-HASM-675virtu...

Hopefully they all fit together!

I have an arduino mega so I could take the gimbals and switches out of an old radio and start there. 

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Permalink Reply by andy j on December 8, 2011 at 3:52pm

For those of you interested in the integration manual for the radio - this is the good one

**

http://www.rfm.com/products/data/dnt900dk_manual.pdf

**

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Permalink Reply by flynx on December 9, 2011 at 2:19pm

Awesome, thanks!  According to UPS my DNT900's were just delivered.  Way to go Mouser for FAST shipping and delivery!  Looks like I won't sleep much this weekend.

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