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How expandable is the Picaxe-25?

Hello All.

I'm looking to build the "Start here" robot so I can learn some basics but I want to know how expandable the Picaxe-25 project board is. I would eventually like a robot with more than two motors but it looks like the L293D motor driver can only handle two motors at a time. Is there a way to use the Picaxe-25 project board to drive more than two motors? Are there other chips that will fit on the Picaxe-25 besides the L293D that will drive more motors?

I'm trying to see if this board will be able to grow along with my ideas/skills or not.


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You can always build your own board to get more out of the Picaxe. The project board gets you basic two-way motor control, plus inputs/outputs for other actuators and sensors. You could do a lot of different things with that.

However, if you want more than two motors, you'll need to build a board.

There's also a project board that works with both the Picaxe-28 and -40 parts. However, there is no on-board slot for a motor control, so you would need a separate board for that anyway. I used this board, together with a DAGU motor controller board, on my GRAB-E robot.

You can see pictures of both the Picaxe project board and the DAGU motor controller board on the GRAB-E's build blog. http://letsmakerobots.com/node/11208

So if I build a motor board with more motor control chips on it the Picaxe-25 (or I guess more appropriatey the PICAXE-28X1 chip) can send commands to those chips to drive the motors? Is that right? I see the PICAXE-28X1  has 17 outputs. In theory, would that mean you could send info from it to a chip with drivers for 17 motors or does it take more than one output per motor. Sorry, I am very new to this.

FYI, Frits created a walk through of the project board, which you should read over as it is very helpful. http://letsmakerobots.com/node/75

To use the motor control chip (or pretty much any dual h-bridge), requires four controller outputs from your processor (the Picaxe, in this case). This allows for bi-directional control of two motors. If you added an expansion board with another dual h-bridge motor controller, you could control two more motors in either direction using another four outputs of your Picaxe.

You can re-map some of the the i/o ports of the Picaxe if you need more outputs. Read the Picaxe manual for more info.

Thanks, excellent info. Exactly what I needed. I hadn't seen that walkthrough.

The following link offers a way to drive 2 motors with 2 pins, plus some extra components. It is admittedly more advanced than just sending a bit to each 'side' of the motor to control its direction.


on how to build yellow drum machine he has connected annother motor driver to the outputs (although i dont quite get how this works

http://letsmakerobots.com/node/112 (The Yellow Drum Machine page) and you might get a better audience.