raspberry pi 4 VMX

[Jacob Roth-Ritchie]

Hello,

So, we have some extra money, and I think we are going to purchase another VMX Pi and a Titan MC.  This device will push us to buy a new raspberry pi.  My question is, which one do you all recommend, and why?

Here are my thoughts.  We currently have one raspberry pi 4 which we will use during the season for a co-processor (possibly for ML).  If that is not the 4gig version, I think for that, we need the 4 gig version.  For this task in the off-season, we will also probably be using it to control a VMX (we also want to use that whole setup for vision and as an IMU, but are not there yet).  

So, assuming we already have a pi that will work for the season, what are your recommendations?  We are probably going to continue running our VMX headless (I know this is still a bit of offroading, but so far, the only issue I have run into was the I2C, and it turns out that was not the headless' fault).  So, that will give us some more headroom, but is there a benefit of using a 4 gig Pi (over the 2 gig) as the controller for a VMX Frc practice bot?  If so, what is the benefit? One other potential variable is that if I can figure it out, and we do not make the leap to Java, I would like to build a version of robotpy for the vmx.  I know Python is not as svelt as Java or C++.  Would the extra 2 gigs make a difference here?

Thanks.

~Jacob

[Scott Libert]

>  raspberry pi.  My question is, which one do you all recommend, and why?

I'm an engineer; so I'm highly biased towards the 4GB version of Raspberry Pi, and don't see the additional $20 as a significant hurdle.

However, I can imagine for some $20 is significant esp when balancing budgeting priorities.

My belief is that for current usage models (robot controller), 2GB is indeed sufficient, in fact 1GB on Rpi3B+ was working fine.  However as we move forward with more advanced features (e.g., Neural Network-based vision and motion processing), the memory requirements will grow.  Another related item that may dictate this is accessing the Intel Real Sense sensor (the stereo disparity images or the depth maps).  At some point, we'll reach a point where the available resources will be utilized and pushed to their limit.  I can't predict when this will happen, but I feel confident in predicting that it will.  Sounds like you've already reached this conclusion.

The other thing I'd mention (not an issue if you're treating VMX-pi as headless) is the desktop support that the additional memory (combined with Wifi internect connectivity) can offer in an educational setting.  I believe the complex animations and videos directly on the VMX-pi will become more widely use in the future.

Hope that helps,

- scott

[Charlie Peppler]

My 2 cents...for the price difference (unless you are really pinched for budget), I would tend to err on the side of the version
with more capacity.  It gives you flexibility (even if it's slightly more than you need in some applications).  You can reuse it for different purposes
with the least worry, and it will have a longer life cycle (in case you want to do something like run a robot and a vision system

on the same processor in off season, or something of the sort).

[Jacob Roth-Ritchie]

Thank you both.  This is indeed helpful.  I am by no means an engineer, but I see the logic here.  I was of a split mindset, but I am certainly now convinced.  

The first mindset is that with computers in general, always buy the most ram you can afford especially if it is un-upgradeable (I guess the Coral almost counts as a memory upgrade).

The second is that I have been doing that for a while with personal microelectronics (smartwatches being the worse), and frequently they go EOL before taking advantage of the expanded memory.

However, I realize that the raspberry pi has better longevity support than most electronics (I cannot get over the fact that the Pi Zero is so well supported even by the VMX-Pi.

The other thing I'd mention (not an issue if you're treating VMX-pi as headless) is the desktop support that the additional memory (combined with Wifi internect connectivity) can offer in an educational setting.  I believe the complex animations and videos directly on the VMX-pi will become more widely use in the future.

This combined with your thoughts Charlie brings up an amazing point I had not considered.  I spent so much time thinking about headless that I forgot we actually purchased a portable touchscreen monitor to be able to use the rookie classmate as an effective driver station. So, the pi could easily be a full-fledged computer for us, possibly quite easily.

Thanks again.  I am excited about these products.  Our students will surely reap the benefits of the excellent hardware and wonderful discussions from this group.

~Jacob