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CAD and the Jeston Nano

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Robo Pi
(@robo-pi)
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Posted by: @codecage

@robo-pi

Oh man, I missed the vote!  Not sure I should vote on what you should use, but I've had good luck using Samsung SD EVO and EVO+ cards as well as the SanDisk Ultra, but then I have not been doing the kind of experimenting that you have been involved in.

Yes, I imagine if I would just quit being difficult and act like a normal person I wouldn't be having all these problems.  The EVO Select cards have been working flawlessly when plugged directly into the Nano the way they were designed to be used.

It takes an idiot to screw things up this bad.  And here I am, creating my own nightmares. ? 

DroneBot Workshop Robotics Engineer
James


   
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codecage
(@codecage)
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@robo-pi

Leave at least one computer that you can use to get to the DBW Forum with, so we won't be stranded in the cloud without your wonderful prose from time to time! 

SteveG


   
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Spyder
(@spyder)
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@robo-pi

I may have experienced something that might be of interest regarding the ribbon cable issue

It may or may not be substantive. I purchased an extension cable for my pi cam for the jetson. There weren't many options, so I took what they had, I think it's about 4 feet or so. The jetson booted fine, but, whenever I tried to access the camera, the thing rebooted on me

I thought I had connected it backwards or something, or maybe ruined the camera when I swapped out the lens for the fisheye thing, so I put the original 5 inch cable back in, and it worked perfectly. So I noted very carefully which way the cables faced, and tried the long one again, with the same results, reboot when accessing the camera

I know it's 2 completely separate problems, but both involve a long ribbon cable

Probably just a coincidence tho


   
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Robo Pi
(@robo-pi)
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@spyder

I have a 15 foot extension cable for the Raspberry Pi camera v2 on the Jetson Nano and it's been  working flawlessly.   But it's not a ribbon  cable it's a braided HDMI cable I got from Amazon:

SecurOMax HDMI Cable (4K, HDMI 2.0) with Braided Cord, 15 Feet

 

 

Since both the camera and the Jetson Nano use  the flat ribbon cable connectors I had to also buy an adapter set of  ribbon cable to HDMI connectors.  Got these on Amazon also:

Arducam CSI to HDMI Cable Extension Module with 15pin 60mm FPC Cable for Raspberry Pi Camera Specific (Pack of 2, 1 Set)

 

I've been using this for quite a while now with no signs of any problems.   This is nice because it allows me to place the camera on a  tripod that can easily be moved around  without  any problems.   It's no longer anchored right next to the Jetson Nano.

Of course I did anchor those little adapter boards  at both  the camera and  the Jetson Nano to insure that the HDMI cable isn't yanking on the ribbon cable.   But yeah 15 feet from the Jetson Nano and the Pi Cam works just fine.   

Also there doesn't appear to be any signal boosting circuitry on those adapter cards.  They appear to just be traces that connect the two cables.  So the signals work over 15 feet.

One Caveat I did read on the Amazon  reviews.  A 15 foot cable may not work if you are using a high-speed camera?    I think they call it 4K video?    In any case I'm not using that with the Pi Cam so for me the 15 foot cable is working just fine. Although the cable does claim to be 4k compatible.  But for some people it wouldn't work for certain 4k hi res video.

DroneBot Workshop Robotics Engineer
James


   
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Spyder
(@spyder)
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@robo-pi

Very cool. It never occurred to me that that was even a thing, so I never knew to look for it. But that wasn't the point. The point was "a long ribbon cable".

To get back to your item... I only needed to get the camera from the nano to the spot on the front of the test rig where I mounted the camera holder so I could get visual signal for the autonomous movement of the car. The very front would be the best spot to give me data about things like "top of the stairs" (I have to take 200 pictures for "blocked" and "free" to satisfy the data requirements for the software, without which, this thing is nothing but a really fancy computer controlled R/C toy) so, approximately 200MM would be all I need. The adapters and HDMI cable would be a bit much, although I'm now going to look for a smaller extension ribbon, which it appears they have...

https://www.adafruit.com/product/3671

And Lady Ada even calls it a "thingy", so I like it immediately ? (cuz, y'know, words)

Annnnd, it also just occurred to me that what's missing on the 4ft ribbon cable is a ferrite bead (I think that's what they call the ferrite thingy on expensive cables)

ferritebead

I wonder if that might be what's needed for the nano. Is it possible it's picking up signal interference, which is why your 15ft HDMI cable works ? (cuz it's shielded)


   
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Robo Pi
(@robo-pi)
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Posted by: @spyder

I wonder if that might be what's needed for the nano. Is it possible it's picking up signal interference, which is why your 15ft HDMI cable works ? (cuz it's shielded)

I was think that external noise might be the problem  with the SD extender ribbon.   So I moved the Nano as far from other things like power transformers as I could get it and laid the SD extender ribbon all nice an flat.  But it still wouldn't work.

I was actually thinking of making my own extension cable using a shielded 8 conductor cable.   However, I can't find a nice little SD card plug to plug into the SD card slot.  I've been looking around but haven't found one yet.

I did fine this from Sparkfun electronics.  But they want a whooping $11 for this little board.  Plus I don't even need the SD card socket to be on it.   All I want is the PCB that  brings the SD card connections out so I can solder a shielded multi-conductor cable onto it.   This got me thinking about drawing up my own little boards and having them made by PCBway.    As small as these are I could probably get a bunch of them made on one of those break-apart PCBs.

I could try just cutting off one end of my current SD card ribbon cables and using that SD card connector as the end of a shielded cable.   Lot of things to try.  I still don't have the parts to build the SD Card Boot Hub anyway.  I'm still waiting for them to arrive.    It's nice that these cables came in early as they were ordered at the same time as all the other parts. I tried them first just to be sure they worked, but dag blast it, they don't work!  That put a damper on the whole project real quick.

DroneBot Workshop Robotics Engineer
James


   
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Spyder
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@robo-pi

I wonder. What would stop me from cutting that extra long cable down to the 200mm that I actually need, and just carefully sanding off the insulation enough so that I could plug it into the camera ?

It seems like all I'd have to do is make sure I sand off the correct side (cuz otherwise it'd be, y'know, backwards)


   
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Spyder
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No idea if this worked. I'm not a youtube producer

It moves. On it's own (sorta). Takes forever to boot up for some reason tho. Maybe I should change the setting from 5W mode to 10W mode


   
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Robo Pi
(@robo-pi)
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@spyder

It's Alive!  It's Alive! ? 

Very nice video production!   Nice clear picture, and pretty good audio too for a quick little set up.

Thanks for sharing!

You have about the same amount of floor space as I have.   But you have a moving robot, I don't.  I've been spending all my time burning my brain out studying perceptrons.   It seems like a futile attempt as well since I still have so many unanswered questions.  But I am learning, no question about that. I'm making progress.

I need to get my robots up and running too.  I've been waiting on Bill to provide some nice motor control code. But that's like waiting for a black hole to evaporate. ? ? ? 

I really need to put some time into my robots and get them up and running.   I do have them to where I can turn the motors on and off from my notebook computer, but I haven't yet written any actual  control  programs to be able to drive them around in any organized way.

Here's my robots.  These are old picture so they actually have more wires and circuit boards on them now. 

Robot (2)
Robot (7)

 

 

DroneBot Workshop Robotics Engineer
James


   
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Spyder
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Posted by: @robo-pi

I do have them to where I can turn the motors on and off from my notebook computer, but I haven't yet written any actual  control  programs to be able to drive them around in any organized way.

Actually, don't let yer lying eyes fool you... me either

This is nothing but the simplest thing that ROS gives me. It's called "teleop_joy_node" (there's a separate "node" for everything. Just include whatever node you wish to use in the script)

The best way I can describe it is that the jetson has the motor controller and that's pretty much all it needs, then the ROS translates the signals from the joystick into left_motor and right_motor commands. So all the translation into percentages of motion (speed) are done by ROS and sent to the jetson as "twist" messages. The only connection between the jetson and the motor controller is the 2 wires from the I2C

My desktop computer "publishes" a msg in a "topic", which the jetson "subscribes" to, and then tells the motor controller what to go do with itself

It saves on actual programming... sorta

That's why I described it in my ROS thread as being both easy and complicated at the same time

Unfortunately, without the camera, it'll never be autonomous. I could probably use the ultrasonic sensor, but the camera is the only way I'd ever be able to get it to actually follow me around


   
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Robo Pi
(@robo-pi)
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I think I'm going to put my perceptons on a back-burner for a while and see if I can gain some fine motor control over my robots. ?  I'm burning out my brain on the perceptron studies anyway.  Probably best to take a break from that for a while.

Like I say, waiting for Bill to publish his motor control code is like waiting for a black hole to evaporate. So I may as well just bite-the-bullet and write my own code. ?

DroneBot Workshop Robotics Engineer
James


   
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Spyder
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Posted by: @robo-pi

So I may as well just bite-the-bullet and write my own code. ?

Why, when ROS can do it for you ?

It looks like you've got a pi on each of those bots. It doesn't look like they're connected to anything tho

I've got ROS running on a pi3B. Of course, it's ubuntu, not raspbian, but you get the fine motor control. Also known as "digital proportional". Move the joystick a little, it goes slow, move the joystick a lot, it goes fast


   
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Robo Pi
(@robo-pi)
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Posted by: @spyder

Why, when ROS can do it for you ?

From what I've seen from others who are using ROS it would be far easier for me to write my own code than to mess around with ROS.   Writing fine-control motor code really isn't difficult.  I've just been procrastinating on it.  Not even sure why.  I guess I've been too involved with Jetson Nano, perceptrons, Blender and KiCad lately. ? 

I've also been following Paul McWhorter's courses on the 9-axis IMU and A.I. on the Jetson Nano which is totally different from what I'm doing with perceptrons.

Anyway, seeing your robot running around on the floor has rekindled by desire to get my robots finally  up and running.  As I say, I need a break from the perceptrons anyway.  I've been frying my own neurons trying to understand exactly how perceptrons work.  Especially in terms of writing training algorithms for them and graphically displaying the results.

But no, I don't feel like getting side-tracked into ROS right now.  I'm sure I could write my own motor code a lot faster than I could get ROS downloaded, installed, and running properly.  Plus there's got to be a learning curve there to just to learn how to run it.  I could get my robots running on my own code long before that.  ?

DroneBot Workshop Robotics Engineer
James


   
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Robo Pi
(@robo-pi)
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Topic starter  

Ok, it's been a while since I've been posting about my problems with trying to boot a Jetson Nano using an SD Card Extension Cable.

Just as a summary:  I'm working on designing an SD Card Boot Hub for the Jetson Nano.  The idea is to plug the SD Hub (which will hold 4 SD cards) into the SD Card slot on the back of the Jetson Nano.  And then just choose with a selector switch which SD card from the Hub I want to boot up.  This way I can have four different system configurations on four different SD cards and not need to keep plugging and unplugging them into the back of the Jetson Nano.  That gets to be a real pain after a while.

The first problem encountered with the project: The SD card extension cables were among the first of the parts to arrive.  So I instantly tried one out just to be sure they worked.  And they didn't work!  The Jetson Nano could not read the card through the extension cable and refused to boot from it.   So this was a major set back.

The next bright idea: Before giving up on the project, or trying other extension cables it was suggested to try different brands and/or speeds of SD cards.   With that in mind I bought 2 new SD cards to try.

Note: All cards are 64GB appoximate capacity.

The original Card that wouldn't work was a SamSung EVO Select card rated at a read speed of 100 MB/s

I bought two new cards to try: first a cheap card:

An Onn Keep card that is also rated at a read speed of 100 MB/s (same as the EVO Select)

And a ScanDisk ImageMate rated at 130 MB/s read speed. (a faster card)

I finally got the systems copied over to the two new cards and the Onn boots up through the extension cable!

Yippeeee! Success.  It appears to be pretty stable. I've been booting it up several times and using it with the extension cable and I haven't noticed any problems so far.

Strangely the ScanDisk ImageMate wouldn't boot up either.   It boots just fine if plugged directly into the back of the Jetson Nano.  So no problem when acting like a normal human, but as soon as I start acting like a mad scientist and plug it into the extension cable no go.

So Now I have Mixed Feelings

I feel great that I finally found a card that actually works!   I'm disappointed that the Boot Hub will not be usable with just any cards.

Strangely the good news is that the card that works is the cheapest one of the bunch. ? 

Go figure!  The cheapest piece of junk works while the more expensive cards fail.   What a mixed up crazy world we live in.

DroneBot Workshop Robotics Engineer
James


   
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Spyder
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@robo-pi

Sweet !

Although I would have expected it to be a slower card rather than just a cheaper card, at least you have a success point to move forward with ? 

The only concern I might have is that, since it's a cheaper card, you might wanna make more frequent backups to minimize data loss during a catastrophic card failure which would theoretically be more probable due to it being a cheaper card

Bit of a catch-22 there, eh ?

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

Probably not something you want to add to the marketing literature


   
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