Radio communication

[chrisj]

Hello,

Has anyone ever tried using radio frequency to communicate with the roboRIO instead of wifi?

My team is working on some projects in the off season, and we're wondering if this is possible.


Chris

Coach
Team 3812
Bits & Bots

[cad321]

Although I haven't with the roborio, I have done something like this using an arduino. I took an RC remote receiver and hooked its outputs up to the analog inputs on the arduino. I could then interpret the signals from the receiver and use them as controls for things such as a mecanum bot I had been working on or my r2d2. I would imagine the same thing would be possible using the roborio.

[EricH]

Originally Posted by chrisj

Hello,

Has anyone ever tried using radio frequency to communicate with the roboRIO instead of wifi?

My team is working on some projects in the off season, and we're wondering if this is possible.

Just so we're clear: This would be offseason use ONLY. Use of such a system on a competition robot would violate multiple FRC rules (unless, of course, those rules get changed for 2016).


That being said, I think AM has something along those lines, though IIRC it's pointed at being its own controller on the receiving side.

[chrisj]

Yes, we are very aware of the communication rules for FRC. But that is a good reminder. This project is outside the competition scope.

We might have to look into using an arduino, but since we're so familiar with the roboRIO and the programming now, it would be nice to use that system.

There's a Radio light in the roboRIO. Is that for Radio signals or does it illuminate when the D-Link is connected as well?

[EricH]

Originally Posted by chrisj

There's a Radio light in the roboRIO. Is that for Radio signals or does it illuminate when the D-Link is connected as well?

D-Link, AKA "robot radio". I think that's a bit of a holdover from the IFI system on whatever its frequency was...

[Mark McLeod]

The radio indicator on the roboRIO is not currently used.
It'll always be dark.

The FRC roboRIO safety interlocks will be listening for Ethernet communications, so any non-wifi solution needs to convert to Ethernet into the roboRIO.
While doable it'd certainly be much easier and cleaner to substitute an alternate control system.

[chrisj]

Thanks guys. That's good to know that radio control has to run though the ethernet port. We're looking into what other control systems are doable.

We're basically making an RC truck with an actuating arm. So if anyone has a good idea, I wouldn't mind hearing them, but I might have to move to another forum for that.

[EricH]

Originally Posted by chrisj

We're basically making an RC truck with an actuating arm. So if anyone has a good idea, I wouldn't mind hearing them, but I might have to move to another forum for that.

Could try one of AM's alternate control systems: http://www.andymark.com/product-p/am-2520.htm

[cad321]

Although I don't know the specifics on how this might work (or if it's even possible) you could look at using an arduino Ethernet or an Ethernet shield paired with an arduino to receive the commands from the receiver and then push them out over Ethernet. Again, I don't know how one would go about doing this, just a suggestion.

[Greg McKaskle]

As mentioned by others. The roboRIO doesn't have any RF transceivers built into it. Information can flow into it through any of the communications busses -- serial, I2C, SPI, USB, ethernet, or CAN. So if you find an RF device that bridges to any of those busses, you can incorporate it. The enable/disable protocol of the DS is always ethernet, but can be delivered over wifi, USB, or an RJ-45 physical ethernet connection.

Greg McKaskle

[BenGuy]

Originally Posted by chrisj

Yes, we are very aware of the communication rules for FRC. But that is a good reminder. This project is outside the competition scope.

We might have to look into using an arduino, but since we're so familiar with the roboRIO and the programming now, it would be nice to use that system.

There's a Radio light in the roboRIO. Is that for Radio signals or does it illuminate when the D-Link is connected as well?

Technically WiFi falls within the radio range on the electromagnetic spectrum, so the terms can be used interchangeably (although for lack of confusion, most people just refer to radio as the lower frequency portion of the range). So when the radio light comes on, that means that it's broadcasting at either 2.4 GHz Wifi or 5GHz WiFi.

[teslalab2]

With low level access to the mxp port it would be very easy to open a digital serial to some device such a radio receiver.

[GreyingJay]

The AndyMark "Cheap and Dirty" control system is designed to connect the receiver directly to the PWM input of a motor controller (well, up to six of them, specifically).

So presumably you could connect the PWM outputs from the RC receiver to the DIO of the RoboRio, and use those inputs to drive whatever robot code you want to run.

[teslalab2]

It would be much less work to just run the RC to an arduino and drive the motor controllers from that.

[gblake]

I *have* to start by summarizing what BenGuy already mentioned: WiFi is "Radio"!!!!

OK - Now that I have that off my chest - I recommend looking into software-defined radio equipment aimed at hobby markets.

I can't recall the names, but I know I spotted some interesting project/product descriptions recently.

Using software-defined radios, I think you could build your own protocol (layers) from the ground up (no pun intended).

I don't know if you could find equipment operating in the bands you want to use, but I'm optimistic.

Blake