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Too Many Choices...Need Suggestions


#1

So when I first came to TinyCLR.com, there was only the Mini and Domino. Now there are too many to chose from.

I have stated before, and will restate…

I am looking at building an Underwater ROV. I pretty much have the mechanics down, but I am looking at a controller system.

I need help in which one would best work for me. I am no computer wiz and I have no experience with micro controllers, thus why I am here, seems easy, FEZ!

Well my application will be:

Topside
Laptop - to control/monitor video
Power Source - 12 volt battery

Tether
Probably cat5 cable
Power cable

Bottom Side
Multiple DC motors ( need to be directional, forward/reverse and left and right and another set for up and down)
Lites on/off
Possible accelerometer
Possible leak detection (simple wet trip circuit)
Possible Pressure sensor

I have been thinking because the range could be greater then 500 feet on the tether, as previously suggested communication over RS232 with an RS485 converter.

So I ask the forum, what would be the Best (ok, cheapest) FEZ for this job and hardware?

Any suggestions?

cncmike


#2

Pretty much any FEX will work for this application, but you probably don’t quite need the power of a Cobra. I think a Domino or Mini would be a good choice.


#3

I’d approach it by thinking how many connections to monitors or controls will you need.

eg How many control wires per motor (or pair of motors) are you going to need?

Total up those requirements, and see what might suit based on it’s configuration. Panda will be good since it brings small form factor with many IOs and potentially a cheap price point - but until you figure out how many IOs you need that may be unnecessary. http://www.tinyclr.com/compare/ is a great starting point.

Also, how are you going to run vide back to the surface - I’m assuming that’s separate to the RS232/485 over the Cat5, and not inter-connected to Fez?


#4

Buy the least expensive fez that is available within your timeframe to start. Start learning about the device and how to program it.

After a while you will be able to answer the question yourself.

There are lots of questions, which you may not know yet, that are necessary to arrive at an answer.


#5

Additionally, if you really need to you can use some of the low cost components help augment the functionality of Fez. The general advice around here seems to be that if you’re doing prototyping that you should go with what ever has the most options, design the app, then reduce (or increase) the device requirement based on the design.

As for writing the application that controls it; simply “haunt” the forums :smiley:


#6

I purposely didn’t respond to see what will the community suggest. I feel that we have a community strong enough to handle every newbie coming here…

Thanks guys :slight_smile:


#7

Well thank you to everyone.

Because I am new to all of this, I am thinking after reviewing the compare sheet, I am gonna hold out for the Panda and like the suggestions, get some misc addon components also for it.

The video will be separate from the control system. I have a couple cameras that work on wireless. I am hoping I can just use a wire to transmit up the signal along the tether and that should be sufficient to plug the receiver into a capture device. Hopefully I won’t need to boost the signal. It’s all learning and trial and error at this point.

Once I get the Panda and get rolling, I am sure I will be here probably bugging you guys alot. Hopefully because it’s simple, I will be able to find alot already here.

Thanks,

Mike in MN


#8

I probably going to loose experience points from this post, but do you really need a microprocessor in the ROV itself?
Im building one for my kids (well, -mostly for myself) that uses two serial motor controller boards to control the three thrusters on my ROV http://www.pololu.com/catalog/product/1110
Here is a link to my project http://letsmakerobots.com/node/19254
On the other hand having a FEZ Cobra on the topside with at TFT monitor would be awesome.
(Maybe this helps me keep my experience?)
Hum… I might revise my control system…


#9

You could omitt a micro controller from the project al together, but then you would have to string wiring for EVERYTHING on the tether. Why do that when you could just use the uC as an endpoint?


#10

Hey Chris,

Do you suppose that the Nordic radio will work underwater? if not then perhaps line of sight infrared?


#11

Hi Chris
My point is that you need more than just a microcontroller at the end. At least you need a motor controller for at least 3 motors and if the sole purpose of the uC is to control the motors I feel that a FEZ is a bit overkill.


#12

Hi Geir, I see what you mean. My point was actually about the sensors. If he wants an altimeter and stuff then he would be better off with just a uC controlling it.

@ kurtnelle. Well, RF does work underwater. Not sure how far down it will go but if I were doing anything underwater I would rather have a tether. If anything goes wrong over a wireless link, you’ll have to dive down and get it. Plus, you would also need to provide batteries.


#13

This is a perfect reason to use a microcontroller. Once things go wrong (no signal) then you can take a recovery route to recover your system.

Does a microwave need a micro? No it doesn’t, just put an on/off switch. But you have a FEZ then you can have timers, defrost method, clock…now add a FEZ Cobra and now your microwave have a color touch screen that streams stock info and internet radio…and can give you cooking recipes.

It is really up to you to how far you are willing to go with the “microwave” design.

When it comes to RC, you can take advantage of the further possibilities AFTER you do simple forward/backward…sensors starts coming in…of course if all is needed is the basic function then yes FEZ is an over kill to just make an LED blink or make an RC car move forward.

So, you are correct but I would think a bit deeper of what other possibilities I can do when I add a micro, especially FEZ.


#14

Chris,

Well that’s the beauty of using a microcontroller :slight_smile: If something goes wrong with the wireless link; the software will just bring it back to the surface.


#15

First nice profile pics…was a surprise when I logged on…

Well thanks for all the discussion on this subject.

I do agree that a microcontroller is a bit of an over kill. My first mock up right now is a simple switched joystick control box which will fire a signal to a 10-channel 2-wire remote system I got.

The biggest reason why I want to learn about micro’s is to expand the functionality of it. I would like to use a manipulator arm, pressure sensors, accel sensors, maybe if possible GPS, backup surface protocol.

I have been reading about industrial ones, they have alot of functions, and you never know what will fun to add on later.

If anyone is interested I did start a little site/blog of it at: http://rov.cncbasics.com/

Long term I am conceptually thinking that a FEZ with Ethernet will run anything possible I want to throw at it… :slight_smile:

Mike in MN