Mega and Motor Controller questions

Hi All, it's a very long time since I've been on, how are you all?
I've just bought and built a Tamiya tracked chassis with dual gearbox and I now want to control the motors, both directions with variable speeds. I'm looking for either a motor controller that plugs straight into my Mega which doesnt use a Uno board style or a fully supported DIY motor controller that I can wire onto a Mega proto or I suppose as a last resort a schematic that will achive the same outcome.
I've looked everywhere and can only seem to find boards in an Uno format or what seem as dodgy DIY motor kits that I am unsure if they will be supported.

Thanks guys
Adam

that plugs straight into my Mega which doesnt use a Uno board style

Unless you have some strangely shaped clone, any UNO shield will fit the Mega.

Oh right I thort the Uno was wider....fail, will I still have access to all the Mega's pins or will the shield cover some up making them unuseable?

will I still have access to all the Mega's pins or will the shield cover some up making them unuseable?

All except those that the shield actually uses. If you use the right kind of headers, that is.

Ok, so from what I can see if I was to get for eg:the genuine Arduino controller http://arduino.cc/en/Main/ArduinoMotorShieldR3 id only relatively loose pin 6 and possibly pin7 and tx314? as the overlap of the board looks like it will cover. Just for clarifications sake though do you know of any fully supported DIY motor controller kits that I can build onto a proto, I want to add an xbee too so I could in theory (pin usage permitting) build both circuits onto the one proto. I'm getting beyond myself now as I've not even checked if they do a DIY xbee but I think if I build it I'll understand it more.

thanks for the advice BTW I appreciate it

From your link:

Input and Output

This shield have two separate channels, called A and B, that each use 4 of the Arduino pins to drive or sense the motor. In total there are 8 pins in use on this shield. You can use each channel separately to drive two DC motors or combine them to drive one unipolar stepper motor.

The shield's pins, divided by channel are shown in the table below:

Function pins per Ch. A pins per Ch. B
Direction D12 D13
PWM D3 D11
Brake D9 D8
Current Sensing A0 A1

So, I don't know where you got the idea that only pins 6 and 7 are used, nor do I know what you mean by tx314. I assume that is a typo.

You can stack shields. An XBee shield should easily fit on top of the motor shield.

I've not even checked if they do a DIY xbee but I think if I build it I'll understand it more.

XBees are not open source. The schematics are closely guarded secrets.

PaulS:
So, I don't know where you got the idea that only pins 6 and 7 are used, nor do I know what you mean by tx314. I assume that is a typo.

Sorry I didn't explain myself properly what I meant was, I understand that the shield sits on the required pins which are then available if not used by the boards function from the top of the shield and the ones that arent taken by the shield are still available direct from the board but pin6 pin7 and (tx3 14) look like they will be covered by the tail end of the shield...not that it matters much I'm just trying to make sure I know what I need

XBees are not open source. The schematics are closely guarded secrets.

I'm sure I've seen some sort of full form shield that you plug the Xbee into? dunno

but pin6 pin7 and (tx3 14) look like they will be covered by the tail end of the shield

Ah, that makes sense. In that case, you could get extra header connectors and make spacers between the motor shield and the Arduino, like this: Arduino Stackable Header - 6 Pin - PRT-09280 - SparkFun Electronics They come in 8 pin lengths, too. That would give the needed clearance to wire to the pins that might be obscured, but not used, by the shield.

I'm sure I've seen some sort of full form shield that you plug the Xbee into?

Sure. http://www.sparkfun.com/products/9976

I thought you were talking about making an XBee.

todda:
I've just bought and built a Tamiya tracked chassis with dual gearbox and I now want to control the motors, both directions with variable speeds.

Before we go too much further - which Tamiya tracked chassis are we talking about?

We can probably assume you're talking about their small plastic kit they sell, that uses 3-6 volt motors; but just so we don't bumble down the wrong path, can you provide a link to the product?

Tamiya sells a variety of R/C tank chassis kits, some quite large with powerful motors, which no ordinary Arduino shield can drive - for these kinds of chassis, the choice of the motor controller will be vastly different.

cr0sh:

todda:
I've just bought and built a Tamiya tracked chassis with dual gearbox and I now want to control the motors, both directions with variable speeds.

Before we go too much further - which Tamiya tracked chassis are we talking about?

We can probably assume you're talking about their small plastic kit they sell, that uses 3-6 volt motors; but just so we don't bumble down the wrong path, can you provide a link to the product?

Tamiya sells a variety of R/C tank chassis kits, some quite large with powerful motors, which no ordinary Arduino shield can drive - for these kinds of chassis, the choice of the motor controller will be vastly different.

Yeah don't worry its only the twin 3v one.
http://www.tamiyausa.com/product/item.php?product-id=70108 - chassis
http://www.tamiyausa.com/product/item.php?product-id=70168 - Gearbox upgrade

PaulS:

but pin6 pin7 and (tx3 14) look like they will be covered by the tail end of the shield

Ah, that makes sense. In that case, you could get extra header connectors and make spacers between the motor shield and the Arduino, like this: Arduino Stackable Header - 6 Pin - PRT-09280 - SparkFun Electronics They come in 8 pin lengths, too. That would give the needed clearance to wire to the pins that might be obscured, but not used, by the shield.

I'm sure I've seen some sort of full form shield that you plug the Xbee into?

Sure. SparkFun XBee Shield - WRL-12847 - SparkFun Electronics

I thought you were talking about making an XBee.

Sweet that answers that one, what do you think for this one? do you think A) its any good and B) how difficult would it be to build onto a Mega proto rather than the supplied uno PCB