Using an Operator Interface with the 2004 EDU RC wirelessly

[Guilherme]

I got it! It´s working know.

We have no AC adapter to our OI, so the used voltage was somehow making the communication between the Internal Radio and the RS-422 Data Modem fail.

I made an Y cable to turn on both EduRC at the same time.

I made some modifications to the code, just to test. But the code available to download works perfectly!

Thanks all for your help! You´re great!

[Neal Probert]

Could we not just plug in the 2003 radio modem directly into the 2004 EDU/Full-Size RC?

Of course, we'd need to know the 2003 communications protocol to write the receiving code in C. Is this documented anywhere? Better yet, is anybody working on this?

This would be a good engineering challenge for the students.

[Dave Flowerday]

Originally Posted by Neal Probert

Could we not just plug in the 2003 radio modem directly into the 2004 EDU/Full-Size RC?

The reason we chose not to solve the problem this way is that it would be significantly more complicated for other teams to duplicate. The radio modems use RS422, so a converter would be necessary to get either an RS232 or TTL signal to hook up to the 2004 EduRC. Additionally, the radio modem requires an input that toggles it between command & data modes, which would have to be hooked up to a digital output on the Edu. Finally, the OTA (over-the-air) protocol is only partially documented for RC->OI communication and entirely undocumented for RC->OI. Also, using the old Edu provides an easy way to set the team number =) (otherwise it would probably have to just be a constant in the software).

[Dave Scheck]

Originally Posted by Neal Probert

Could we not just plug in the 2003 radio modem directly into the 2004 EDU/Full-Size RC?

We won't know until Saturday about the full-size controller, but as for the EDU...

The reasons that you can't plug the 2003 modem into a 2004 EDU are

1. It doesn't have a modem port.
You could create an external box that converted the serial signal of the modem to the inputs on the EDU. This would require a relatively simple microprocessor circuit.

2. You can't plug it into the serial port because the voltage levels are incompatible.
You could create an external box to shift the level of the modem signal, then plug into the serial port, and write some interface code to process the signal.

While both workarounds are good challenges, Dave's solution was designed to be a quick, low cost for teams that have a 2003 EDU, but do not have the resources to design the necessary interface circuitry.

I would imagine that at this stage in the game that most teams would be more interested in exploring how to write functioning C code than creating interface modules.

EDIT: Dave beat me to the punch in replying, sorry for the duplication

[Guilherme]

Don´t forget that the 2003 EDU has an internal modem, so it´s not necessary to use the any other radio.

Just build one cable, inverting ports 2 and 3 as said in this topic, and it´s all set! Just download the code, turn on the Operator Interface with the radio, and the 2003 EDU will trasmit data to the 2004 EDU. Simple serial communication, that´s all.

[Astronouth7303]

Why not connect the PWM outs from the '03 EDU to the '04 EDU PWM ins? Basically do the same thing you already are, just remove the programming hassle. The only thing I don't know is what wires to connect (Ins are 3, outs are 4). The volatages should be safe (The hobby recievers only use up to 6v, the IFI EDU motors are expecting 5.5v to 8.6v).