Need Help w/ Jeenode (RFM12B) and HBridge. Please.

I am building a medium to medium large differential drive bot. I have two jeenodes from moderndevice.com. http://shop.moderndevice.com/products/jeenode-kit and a USB-BUB for programming them from the same place. I went with them instead of a dedicated R/C controller because I wanted to learn something in the process and Richard Crowley recommended them a couple of times.

My H-Bridge is a sabertooth 2x25 from www.dimensionengineering.com

I assembled both my Jeenodes (@ about 75 solder joints each, very scary for someone like me ;) ) and loaded the RF12 demo that came with. I switched the nodes over to the proper (for my chip) 915mhz band from the 433mhz they came programmed with, and assigned each node to its own terminal. I sent some test packets and got an acknowledgement from the other terminal (powered off battery.)

The RF12 demo that it came with is not written in typical "arduino code" it is written in either processing or C ( I can't tell the difference yet) and I can't make heads or tails of a lot of it. Hours of searching documentation and forums at jeelabs has only turned up people using these modules as small monitors for networks for green houses or residential climate control, or pulling info from the net and sending it to a terminal.

I went "all in" on the H-bridge which has many different options for how it can be setup, based on 6 jumper switches built in. The following are the ways it can be setup.

  1. Analog Control/Linear/Independent 0-5V analog input 0 is full reverse 5v is full forward, 2.5v is stop

  2. Microcontroller pulses/Independent linear control R/C servo signal with pulses of 1000us-2000us for speed, 1500 is stop

  3. Radio control, differential drive, exponential The Sabertooth will autocalibrate the center and endpoints of the signal

  4. Simplified serial , 38400baud Control is single byte commands Motor 1: 1 is full reverse 64 is stop 127 is full forward. Motor 2 : 128 is full reverse, 192 is stop, 255 is full forward.

  5. Packetized Serial, address 128 Control is via a multi-byte packet

Also need to note that the Jeenode runs 3.3v logic levels, not 5v.

I think that is most of the information needed for my questions, if not i can track down links to the datasheets, I just currently have them all saved as pdfs on my computer.

Ideally, I would like to later be able to add more functions to my bot, but for now i am just concentrating on the drive system.

Here are the questions.

  1. I don't have a problem with hours and hours of researching, but have I picked an option here that may be beyond the scope of what I can reasonably learn in a few weeks? If thats the case I should just buy a dedicated R/C controller?

  2. The Jeenode runs 3.3v logic and also defaults at 57800baud. Do I need to run the Jeenode to a 5v logic arduino (if i want to add additional functionality later.) because of the logic level and that high of baudrate? Responsiveness is a key priority.

  3. Of the 5 ways my H Bridge can be setup, is one way going to be much preferable than other ways? For instance, I can 'visualize' how to make it all work using Analog-Linear control, but If any of the other 4 ways are much more desirable, I'd rather spend the time and effort learning how to program it for the most IDEAL way of control. Simplified Serial is another way I can 'visualize' how it will all come together. Basically, I don't want to go off chasing dragons.

  4. I am having trouble finding much information/code concerning the Jeenode. I have heard of the Xbee12. Do they probably function in much the same way, meaning I can also search for Xbee information?

In summation, I have several paths to my goal, and am not entirely sure what my constraints (as far as hardware) are. Any/All links or information or ideas are appreciated.

Thanks for any and all help.

THANK YOU RICHARD!

I don't feel like I know enough about your situation and constraints to make any sort of recommendation.

I have no constraints as far as time for completion, I just wasn't sure if it was possible or not. Remember I am extremely new to all of this. I've come a long way from a couple of weeks ago, but with so much encompassed, I am sometimes confusing what I learn because 100% retention is not possible.

Logic level conversion is pretty trivial. Certainly doesn't require another Arduino. I don't see how adding another Arduino would have any positive effect on either speed and/or responsiveness?

Mostly, I don't really know anything about 3.3v logic levels. Everything I have been self studying the past couple weeks has dealt with 5v logic, so I had no idea what, if any, problems might arise from that. My main concern was if I was using analog/independent which wants 5v high for full forward, and I thought 3.3v meant output scale is going to be 0-3.3v, which would mean I would need another arduino (or other way of converting to 0-5V) if I went this route.

The other reason I thought i might need another arduino is because of some discussions I have read about how much of the unit is being taken up by serial at 57800 baud. Again, this is a case of me still being new to all this, but it only takes a minute to verify with a question to someone who knows, vs hours/days (for me) of coding.

Again, I don't think we know enough about the rest of your project and how this decision would affect it. I am going for the Packetized Serial mode for my own project (remote-control pan/tilt/zoom/focus/iris cameras)

TBH, I don't have any further plans as of yet. I am trying not to be too much of an overly ambitious beginner (I know I already failed at being an overly ambitious beginner, but I can still control the scale :-?)

Everything needed seems to be available from JeeLabs. Granted, the organization of his website is a bit chaotic. But I'm not hiring him as a website designer. I do not believe that it is that similar to Xbee. Note that working distance, expected interference, and reliability are all factors to consider when selecting an RF link solution.

Yeah the website layout is frustrating me. Every time I think I've found a link that will help me out, I run into a note that says " More documentation is needed here"

Your answers have given me a great starting point as far as what areas I need to start researching first, and I thank you for that.

Anything I can do to help?

I can probably be of more assistance on the forum at http://talk.jeelabs.net/ - which is where I tend to spend more time answering Q's, etc.

As for website improvements: tell me where & what to improve, please. It can help you, me, and others a lot...