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DIY custom 2.4ghz RC radio system for robotics...

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Posted: 2008-10-17 10:07 
This looks great, it will be fun to play(work) on this. If the desire is to also add an LCD display, one option that might make the integration work a little easier would be to use an LCD that handles the keypad. I know that Matrix Orbital makes some that does this (can be controlled both as a serial LCD or I2C). Not sure if there are any cheaper ones that do. Of course if you are planning to use an Atom Pro or a Atmel ATMegaxxx chip to control the unit than it would most likely have the power and IO space available to process this at a lower cost.

On a slightly divergent question (closer to what this was split off from). As another approach, could we somehow plug into the training (buddy) port on the back of our radios (mine is the Laser 6), Hopefully one of the pins has the current signals and could we then manipulate these signals and send them back to the radio? I know we would probably have to modify the radio to either simply bypass the Trainer switch on top or maybe run it as an output to our circuit that programatically presses the bypass switch when we are wanting to interject the pressing of one of the switches? So far my googles have not found the definition of the IO pins or protocal to these... What do you think?

Kurt


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Posted: 2008-10-17 12:25 
kurte wrote:
On a slightly divergent question (closer to what this was split off from). As another approach, could we somehow plug into the training (buddy) port on the back of our radios (mine is the Laser 6), Hopefully one of the pins has the current signals and could we then manipulate these signals and send them back to the radio? I know we would probably have to modify the radio to either simply bypass the Trainer switch on top or maybe run it as an output to our circuit that programatically presses the bypass switch when we are wanting to interject the pressing of one of the switches? So far my googles have not found the definition of the IO pins or protocal to these... What do you think?

I think what needs to be done to accomplish this is for you (someone) to identify the signals coming from the trainer port. Since the current plan has a BAP or an ATMega reading the gimbals, keypad, etc and generating the PPM stream for the rf module I don't see a reason why you could not do the same thing, that is interpret the signals from the trainer port and generate the ppm signal from that.


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Posted: 2008-10-17 14:52 
Ok, almost ready to start some coding. I have almost gotten everything wired up. :D EddieB found the pinout for the Futaba radio module here. I just need to figure out which end to start counting pins from. ;)

Code:
pin 1 = PPM input
pin 2 = +9.6vdc
pin 3 = RF detect out (not used)
pin 4 = Ground
pin 5 = Antenna (not used)


Here's my test setup waiting for the keypads to arrive.


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Posted: 2008-10-17 15:09 
did you crack open one of the airmods to see if you can ring out the connector with a meter or are you going to wait for me to do this next week (before powering that thing up, lol)?


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Posted: 2008-10-17 15:21 
EddieB wrote:
did you crack open one of the airmods to see if you can ring out the connector with a meter or are you going to wait for me to do this next week (before powering that thing up, lol)?


Sure did!




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Posted: 2008-10-17 15:36 
It looks like 6.0vdc in will be just fine as I suspect the regulator is a 3.3vdc unit. The Spektrum DX6i is powered from only 4 AA cells. The only thing left to figure out is if the PPM pulses are 0 to 5vdc or 5vdc to 0. The testing I've done so far is Spektrum native format 5vdc to 0, and is the same as JR, but I think Futaba is 0 to 5vdc.

Ho! cool! 8)

1 = signal = yellow
2 = power = red
3 = ground = black

A servo extender cable almost works. The pins aren't quite long enough. :(

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Posted: 2008-10-17 15:57 
Hey EddieB did you get your GWS gimbals yet? Was wondering if they will mount onto a panel like the Laser ones do. Let us know about the quality as well. :D

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Posted: 2008-10-17 16:10 
Robot Dude wrote:
Hey EddieB did you get your GWS gimbals yet? Was wondering if they will mount onto a panel like the Laser ones do. Let us know about the quality as well. :D


Nice Pic! Looks more like a robot radio :lol: .

didn't you say you had an injection molded case being made for the chassis? if so, got any drawings of it?

Now you need to laser cut 2 places for a metal-ring swivel to attach straps to go around your neck. Then you can hold this thing at waist level.

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Last edited by SN96 on 2008-10-17 16:13, edited 1 time in total.

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Posted: 2008-10-17 16:10 
Robot Dude wrote:
Hey EddieB did you get your GWS gimbals yet? Was wondering if they will mount onto a panel like the Laser ones do. Let us know about the quality as well. :D

Be like Wednesday night if UPS tracking number is to be believed. Sry, I paid the flat rate shipping charge... :P


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Posted: 2008-10-17 16:13 
SN96 wrote:
didn't you say you had an injection molded case being made for the chassis? if so, got any drawings of it?

actually if it isn't too big I can probably vacuum form a swoopy back part, although I think Jim actually said he cut the panels to fit in a standard hobby box or something.


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Posted: 2008-10-17 16:13 
SN96 wrote:
Robot Dude wrote:
Hey EddieB did you get your GWS gimbals yet? Was wondering if they will mount onto a panel like the Laser ones do. Let us know about the quality as well. :D


Nice Pic! Looks more like a robot radio :lol: .

didn't you say you had an injection molded case being made for the chassis? if so, got any drawings of it?


Yeah I did say that. lol Well it arrived and it didn't look much like the image on the website. It's about 1" too tall. I am looking into better options. This is fine for testing anyway. :)

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Posted: 2008-10-17 16:15 
You guys ran over me. I edited my post but I'm to late lol :lol: .

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Posted: 2008-10-17 16:40 
SN96 wrote:
You guys ran over me. I edited my post but I'm to late lol :lol: .

Mike you snooze you loose, or at least get mocked. :P

Jim I can't make out the regulator part number but based on the capacitors and what I think I can see from the traces I suspect the black numbers are correctly assigned to the pins. The RF-Detect out is a active low signal from the final output stage of a normal module so they are just hard tying it low, thus that defines pins 3 and 4, and the trace appears to connect to the tab pin of the regulator and both filter caps suggesting it's GND. You can check the connection of pin 2 to the voltage regulator outboard pin but I think I can see the trace, and the inboard pin of the regulator appears to go down into the guts of the controller and stuff so that's likely the regulated output. Pin 1 would be a signal trace so that jives. Very funny though that this pinout is backwards to the common notation of pin 1 being the square pad of the connector... sneaky bastidges or someone oopsed perhaps... is Mike free lancing for spektrum these days? :twisted: :P ;)


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Posted: 2008-10-18 09:33 
EddieB wrote:
SN96 wrote:
You guys ran over me. I edited my post but I'm to late lol :lol: .
is Mike free lancing for spektrum these days? :twisted: :P ;)


Ah ha ha ha...

pin 1 squared pad numbered counter clockwise. Same for through hole square pad indicates pin 1 of polarized components.

did I pass Eddie? did I? :P

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Posted: 2008-10-20 13:18 
Ok I've got the signals formatted properly for the Airmod. The reason I know this is part of the binding process tells you to move the servos to their failsafe positions. My previous attempts to bind where without sending the pulses to the transmitter. It would never bind. I used the same positive going pulse as the Spektrum radio used and viola it would bind. Now that it's bound to the receiver I'm ready to read the joysticks and do some math to get the values correct. Right now I'm getting the following from the A to D's...

Code:
       625              621
        |                |
        |                |
393 ----o----630  393----o----634
        |                |
        |                |
       418              404


Which means I'm only getting 240 points on the horizontal and 210 points on the 210. :'( I'm not sure if this a problem or not, but it looks like a problem to me. Anyway I'm about 10 minutes from making the servos move from the joysticks in real time. :D

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