CAD and the Jeston Nano  

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Robo Pi
(@robo-pi)
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2020-01-08 3:38 am  
Posted by: @spyder

A more efficient card mounting system requires cards that are more prone to failure thus making the system less efficient

I don't know why you would assume that they are more prone to failure.  They already outperform the more expensive cards.  Perhaps they are better designed cards all the way around.   This wouldn't be the first time a less expensive product turned out to be far better than a more expensive product.

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James


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Spyder
(@spyder)
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2020-01-08 4:34 am  
Posted by: @robo-pi

I don't know why you would assume that they are more prone to failure

Because without that simple assumption, the whole premise of my joke flies meaninglessly out the window, without even any feathers pretending to be wings, leaving my punchline to go over as well as something resembling nothing more than a led balloon


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Robo Pi
(@robo-pi)
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2020-01-08 5:12 am  

On a positive note the 4-position rotatory switches for the SD Card Hub came in today.  ? 

Still waiting for the electronic switching chips, and the SD Card sockets to come in.   I'm going to have a problem building the prototype as the SD Card sockets need to be soldered down to a PCB in order to work.  And I don't have a PCB to solder them onto.  I was hoping to build something on a breadboard as a test circuit.  But I might not be able to do that.  I might need to bite the bullet, have some PCBs made up and just see if they work.

I do have some old two-sided blank copper pcb boards here.  I used to make my own pcbs years ago.  I actually drew on them with some kind of special marker pen and then set them in a bath of etching fluid.  I don't have any etching fluid.  I suppose it's time to order some. 

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James


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Robo Pi
(@robo-pi)
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2020-01-08 5:46 am  

Looks like vinegar and hydrogen peroxide are all that's needed to etch a circuit board.  So I'm all set for making a crude prototype.  Just need some parts.

 

I should probably make a video of this project just to get my feet wet with making videos huh?

This post was modified 3 months ago by Robo Pi

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James


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codecage
(@codecage)
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2020-01-08 2:31 pm  

@robo-pi

I had somewhat the same thought as @spyder, in that maybe it would be a slower card that worked!  What are the odds that the knock-off cheaper card, while advertised as reading at a 100MB/s, is in reality much slower?  If you could find a slower version of one of the Samsung cards would that be a valid test of using slower (more reliable?) cards?

SteveG


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Robo Pi
(@robo-pi)
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2020-01-08 8:22 pm  

@codecage

Yes, what you say may very well be true as I currently have absolutely no clue why one card works and another one does not.  It could very well be a speed issue.  If I were a research lab with unlimited funding I could investigate the problem thoroughly by trying lots of different scenarios.   Unfortunately Robo Pi Labs is running on near empty in the financial department.   It costs a minimum of 10 bucks a crack to try a new card.  Possibly more if I'm going to try a higher quality (more expensive) card that has a slower speed.

But keeping with your idea I'm wondering if there is anything in the Jetson Nano OS where I can manually set the max read speed it is permitted to use?   Is it possible to tell the OS to use a slower speed even when a card is capable of a higher speed?  If that's possible I should be able to just tell the Nano to read cards slower and maybe then all these cards would work?

That would be an experiment worth performing, if it is indeed possible.   I currently have no clue if I can tell the Nano to read the SD Card slower?  I haven't done any research on that yet.  I'll go see if I can Google something up right now and let you know what I find.  If that works that will be a free experiment saving Robot Pi Labs from financial destitution.  That would also allow me to use all my current SD cards which would be a fantastic outcome. ?

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James


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Robo Pi
(@robo-pi)
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2020-01-09 5:42 am  

I made a little progress toward the idea of limiting the read speed of the Jetson Nano.  Unfortunately it looks like it's going to require another Ph.D. in learning the Jetson Nano OS.

It can supposedly be done by modifying this file: sdhci-tegra.txt

Unfortunately, exactly how to find this file on my Jetson Nano has eluded me. I've searched for it and haven't been able to locate it.  Not to mention that I'm not even sure exactly what I should change on the file if I ever do find it.

One thing I do know is to make a back-up of it immediately before attempting to modify it. ? 

Clearly if I mess up defining how it reads the SD card it's never going to boot on that card again.  I'd need to go back into that card reading it as a data card, and restore the original file to hopefully get it back up and running again.

In the meantime I can't find the file, nor do I know what to change on it.  So baby steps for now.  At least it appears that there is a way to address the read speed.  Now all I need to do is figure out how to do that.

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James


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Robo Pi
(@robo-pi)
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2020-01-09 7:11 am  

I've been talking with the people at NIVIDIA.  They are suggesting that instead of building an SD Card Boot Hub that I should just reconfigure the Jetson Nano to boot from the USB port and then use a switchable USB hub to switch between system cards. 

What a bummer!  My entire invention down the drain. ? 

Oh, well, I'm better off getting back to building robots anyway. ? 

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James


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codecage
(@codecage)
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2020-01-09 2:58 pm  

@robo-pi

But it works on a RasPi correct?  If that is the case I be interested in one at least, maybe even several!

SteveG


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Robo Pi
(@robo-pi)
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2020-01-09 6:28 pm  
Posted by: @codecage

But it works on a RasPi correct?  If that is the case I be interested in one at least, maybe even several!

Hopefully the finished product will work on the RasPi.   The extension cable certainly does so that's a good start. 

I've come too far to quit now.  I've already designed the PCB in KiCad.  I've already ordered all the parts to make at least 5 of them.   And like you say, it does look promising for the RasPi.   I'm don't personally have much use for it on a RasPi since I don't use my pies as Desktop machines.   I also tried this on an older pi.  No guarantee it will work on a Pi4. 

I also have the added incentive to continue considering that it does appear to work on the Jetson Nano as long as I use the Onn SD cards.

So I'll probably continue onward.  If for no other reason than I do have the parts.   If I actually have the boards made up and it works I'll be glad to send you a couple of them.   I might even be inclined to include all the parts. ? 

And, depending on how well I can solder up this SMD stuff I might even consider the possibility of sending  you a couple completely assembled units.  But don't hold me to that one!  It's far more likely you'll just get a package with a board and parts and a note that says, "Good luck!". ? 

In any case, it's going to be a while yet.  Some of the parts are still in transit, and I haven't even ordered the PCBs yet.   I wanted to wait until I have a working prototype first.

I'll keep you posted on what's happening.  I might even start a thread dedicated to this project once all the parts are in and I start doing some actual prototyping tests.  This thread was supposed to be about CAD on the Jetson Nano and I derailed my own thread with this SD Card Boot Hub thingy.

By the way very special thanks to doc @spyder for pointing me to Blender for the Jetson.  It's working perfectly and I LOVE IT!  And by the way, for anyone who's interested NIVIDIA actually has a close relationship with Blender and that's probably why Blender 2.79 runs so fast and flawless on the Jetson Nano.  It's no doubt taking full advantage of the 128 core GPU.    Also for anyone interested, Blender 2.8x has not yet been implemented on the Jetson Nano.  But since NIVIDIA and Blender are working together I suspect that we might see a Nano version of Blender 2.8x at some future date.  That's just a hunch on my part.

Anyway, when I begin the actual prototyping tests for  the SD Card Boot Hub I'll start a new thread just dedicated to that project.  I've come this far, I may as well finish it now.

DroneBot Workshop Robotics Engineer
James


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byron
(@byron)
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2020-01-09 6:51 pm  
Posted by: @codecage

@robo-pi

But it works on a RasPi correct?  If that is the case I be interested in one at least, maybe even several!

The rpi 3 can be booted directly from usb and also a hard drive.  The rpi 4 is currently lacking this (last time I looked) though it is promised shortly.   Right now the rpi 4 can be booted mainly via usb but need a one liner entry on the boot SD card.


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