The goal of this topic is to show how anyone can make a custom 2.4ghz radio system for robotics. I’m using gimbals (joysticks) from an old Laser 4 radio. The transmitter will be a Spektrum airmod which is a modular 2.4ghz transmitter that accepts a simple PPM data stream. The airmod module binds to a specific receiver (robot) just like the Spektrum radios do. The system will be prototyped with an Atom Pro processor. I may design a board for an Atmel chip later. The best part is I will be using channel 5 and 6 to support a couple 16 key keypads for controlling many functions or physical devices on the robot end. I may add a serial LCD as well.
Well here is the radio top panel version 1.00.
The panel fits an injection molded box that I ordered today. I have lots more work to do to it, but it’s a start.
Make certain you don’t turn the AIRMOD on without an antenna attached… they are quite emphatic about that in their documentation.
I was going to throw up a keypad link from sparkfun but upon thinking about it they really milk the heck out of the cost of a complete assembly so… I am sure there are plenty of economical options available.
Hey EddieB which airmod were you going to use? I’m looking at the DSM2 AIRMOD w/AR7000 FUT-Compatible [SPMMSFUT7] it looks like this.
This is the receiver.
It’s priced at $109.99 for the transmitter module and the receiver, where the receiver alone is priced at $99.99. It’s ordered, just waiting for it to arrive.
lol. well the AR7000 is for big electric and IC planes so I dunno if you needed it but the different modules can be bound to transmitters supporting the same DSM / DSM2 protocol so it’s not a big deal. The AR6100 receiver seems like it would be the better choice to put in a brat or a scout though just because it’s smaller… plus I can use it in my planes. Oh wait did that slip out?
Actually the combination you picked seems to be the lowest price so it is probably what I’ll buy… and maybe an AR6100… oh wait… um… did you consider that you may be able to cut/mill a pocket in the top plastic there to let the module snap in place just like on a r/c radio? You could quite literally just scre the antenna onto it’s output connector without needing to mount the thing internally and provide a mount for the antenna.
Well there were a few things that sort of made the decision for me. The first being they don’t offer any of the airmods with that receiver. You basically get the AR7000 for $10.00 though. It’s got to have the best reception which will be important with the open loop nature of the keypad functions.
Yes I plan to try to make the top panel so the transmitter will snap in if possible. I don’t think the airmods actually includes the antenna. I will know soon enough. I have some 2.4ghz antennas left over from the BlueSmirf projects.
The user manual on the Spektrum site suggests one or more antennas come with the modules to fit the different radios they are intended to be installed in. Looking at the pictures it might be more work to use those than a normal 2.4GHz stubby.
I like the ABCD buttons. I’m curious about the price of the insertable key pads. Spark Fun had dynamic display buttons a while back where each button had its own LCD display.
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?
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.
Ok, almost ready to start some coding. I have almost gotten everything wired up. EddieB found the pinout for the Futaba radio module here. I just need to figure out which end to start counting pins from.
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)?
You basically get the AR7000 for $10.00 though. It’s got to have the best reception which will be important with the open loop nature of the keypad functions.
