A million and one Raspberry Pi questions

Okie dokey, I’m about to get down to brass tacks.

I’ve always been keen for robotics and have watched the rise of SBC/Arduino but have waited for “Just that right project” before dipping my toes in.

Have a read of my blog post for the backstory of my project.

First of all, though, I have to prove to my wife that there’s a viable solution first. A prototype, if you will. After watching a billion YouTube videos, I’ve decided to base my prototype on the DF Robot Devastator Tank with the metal gears, just to see it run and do what I want it to.

It doesn’t have to run for the 3 kilometers (around the block will do) nor does it have to carry anything much (a bottle of beer will suffice), but it does need to answer some questions I have - like what technology it will use to follow the person along. And if this will actually achieve what I want it to.

Firstly, I suppose, I’ve decided to do the project using Raspberry Pi. Firstly to show my nephews what they could be building with their R-Pi’s but also IU just like the thought of coding in something new. (Python) And especially after realising that pwm will control motor speed!!!

(In the spirit of inclusiveness & equality that our house fosters and encourages, I’ve also got an Arduino Uno, but I found that I remembered far too much C++ to find any interest in it, long term. I am convinced that I will find another project better suited to the Arduino shortly.)

So, to get this show on the road, I have my Core Electronics wish list poised and ready to go with bits that I think I will need. RPi 4, 4GB. Check. The PiBow Ninja case to keep it safe. Sure. And to keep the thing cool, the Pimoroni Fan Shim to keep the processor cool and to fit in the case.

Then the motor controller, which is a sticking point.

Firstly, which motor controller? with the devastator, the metal geared motors will be tiny but what amperage do they draw/require? Then, when I get the 12, 24 or 48V motors for the big unit, will a new motor controller be needed?

And, of course, will the RPi, the fan shim, AND either of the motor controllers, fit into the case? And how would that affect cooling, anyway?

I have narrowed it down to two options:

What are your thoughts?

(I have considered Assembled Pi T-Cobbler Plus - GPIO Breakout and would be happy to hear people’s thoughts on using this, also)

Hi Peter,

To get the Devastator going you will probably want to go with the Pololu Dual TB9051FTG Motor Driver for Raspberry Pi it is easy to connect and will drive at about the 2amps needed for the motors on it.
This will mena the fan will not fit but some heatsinks should be enough in this case.

For the Raspberry Pi you just need to make sure that your motor driver supports 3.3V interface and will provide enough current for the motors you are running. Motors and drivers will typically give a few current ratings you want to match the stall current and not the rated current to the motor driver as this is typically the largest load that will be drawn.

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Thank you so very much, Clinton. Based on that, I’ve ordered my gear and I should be getting Devastatored by the end of the week! :slight_smile: