Trans: Latin prefix implying "across" or "Beyond", often used in gender nonconforming situations – Scend: Archaic word describing a strong "surge" or "wave", originating with 15th century english sailors – Survival: 15th century english compound word describing an existence only worth transcending.

Category: DIY (Page 2 of 6)

Decentralized Pi Video Monitoring w/ motioneye & BATMAN

Visit the me here on Github
Added parabolic musings 10/16/19, see below

...On using motioneye video clients on Pi Zeros & Raspbian over a BATMAN-adv Ad-Hoc network

link: motioneyeos
link: motioneye Daemon
link: Pi Zero W Tx/Rx data sheet:
link: BATMAN Open Mesh

This implementation of motioneye is running on Raspbian Buster (opposed to motioneyeos).

Calculating Mesh Effectiveness w/ Python:
Please take a look at dBmLoss.py- the idea here is one should be able to estimate the maximum plausible distance between mesh nodes before setting anything up. It can be run with no arguments-

python3 dBmLoss.py

...with no arguments, it should use default values (Tx = 20 dBm, Rx = |-40| dBm) to print this:

you can add (default) Rx Tx arguments using the following syntax:
                 python3 dBmLoss.py 20 40
                 python3 dBmLoss.py <Rx> <Tx>                 

 57.74559999999994 ft = max. mesh node spacing, @
 Rx = 40
 Tx = 20

Regarding the Pi:
The Pi Zero uses an onboard BCM43143 wifi module. See above for the data sheet. We can expect around a ~19 dBm Tx signal from a BCM43143 if we are optimistic. Unfortunately, "usable" Rx gain is unclear in the context of the Pi.

Added 10/16/19:
Notes on generating an accurate parabolic antenna shape with FreeCAD’s Python CLI:

For whatever reason, (likely my own ignorance) I have been having trouble generating an accurate parabolic dish shape in Fusion 360 (AFAICT, Autodesk is literally drenching Fusion 360 in funds right now, I feel obligated to at least try). Bezier, spline, etc curves are not suitable!
If you are not familiar with FreeCAD, the general approach- geometry is formed through fully constraining sketches and objects- is quite different from Sketchup / Tinkercad / Inventor / etc, as most proprietary 3d software does the “constraining” of your drawings behind the scenes. From this perspective, you can see how the following script never actually defines or changes the curve / depth of the parabola; all we need to do is change how much curve to include. A wide, shallow dish can be made by only using the very bottom of the curve, or a deep / narrow dish by including more of the ever steepening parabolic shape.

import Part, math

# musings derived from:
# https://forum.freecadweb.org/viewtopic.php?t=4430

# thinking about units here:
tu = FreeCAD.Units.parseQuantity

def mm(value):
    return tu('{} mm'.format(value))

rs = mm(1.9)
thicken = -(rs / mm(15)) 

# defer to scale during fitting / fillet elsewhere 
m=App.Matrix()
m.rotateY(math.radians(-90))
# create a parabola with the symmetry axis (0,0,1)
parabola=Part.Parabola()
parabola.transform(m)

# get only the right part of the curve
edge=parabola.toShape(0,rs)
pt=parabola.value(rs)
line=Part.makeLine(pt,App.Vector(0,0,pt.z))
wire=Part.Wire([edge,line])
shell=wire.revolve(App.Vector(0,0,0),App.Vector(0,0,1),360)

# make a solid
solid=Part.Solid(shell)

# apply a thickness
thick=solid.makeThickness([solid.Faces[1]],thicken,0.001)
Part.show(thick)

Gui.SendMsgToActiveView("ViewFit")

"""
# Fill screen:
Gui.SendMsgToActiveView("ViewFit")
# Remove Part in default env:
App.getDocument("Unnamed1").removeObject("Shape")
"""

FWIW, here is my Python implimentation of a Tx/Rx "Free Space" distance calulator-
dBmLoss.py:

from math import log10
from sys import argv
'''
# estimate free space dBm attenuation:
# ...using wfi module BCM43143:

Tx = 19~20 dBm
Rx = not clear how low we can go here

d = distance Tx --> Rx
f = frequency
c = attenuation constant: meters / MHz = -27.55; see here for more info:
https://en.wikipedia.org/wiki/Free-space_path_loss
'''

f = 2400  # MHz
c = 27.55 # RF attenuation constant (in meters / MHz)

def_Tx = 20  # expected dBm transmit
def_Rx = 40  # (absolute value) of negative dBm thesh

def logdBm(num):
    return 20 * log10(num)

def maxDist(Rx, Tx):
    dBm = 0
    d = .1  # meters!
    while dBm < Tx + Rx:
        dBm = logdBm(d) + logdBm(f) - Tx - Rx + c
        d += .1  # meters!
    return d

# Why not use this with arguments Tx + Rx from shell if we want:
def useargs():
    use = bool
    try:
        if len(argv) == 3:
            use = True
        elif len(argv) == 1:
            print('\n\nyou can add (default) Rx Tx arguments using the following syntax: \n \
                python3 dBmLoss.py 20 40 \n \
                python3 dBmLoss.py <Rx> <Tx> \
                \n')
            use = False
        else:
            print('you must use both Rx & Tx arguments or no arguments')
            raise SystemExit
    except:
        print('you must use both Rx & Tx arguments or no arguments')
        raise SystemExit
    return use

def main():

    if useargs() == True:
        arg = [int(argv[1]), int(argv[2])]
    else:
        arg = [def_Rx, def_Tx]

    print(str('\n ' + str(maxDist(arg[0], arg[1])*3.281) + \
        ' ft = max. mesh node spacing, @ \n' + \
        ' Rx = ' + str(arg[0]) + '\n' + \
        ' Tx = ' + str(arg[1])))

main()

Persistent, Live Ubuntu for College

Below is are live mirrors of my "PSU Hacking Club" Ubuntu repos.


https://github.com/psu-hacking/iso-gen


https://psuhacking.club/

https://github.com/psu-hacking/static-site

Simple File Hosting


README yet to be updated with Makerspace-specific formatting


Static site built quickly with Hugo CLI

# on OSX
# get hugo

brew install hugo

# clone site

git clone https://github.com/psu-hacking/static-site
cd static-site

# Compile and compress public directory

hugo
zip -r site-archive.zip public

# upload and host with sftp & ssh

sftp user@yoursite.net
> cd yoursite.net
> put site-archive.zip

# new terminal window

ssh user@yoursite.net
# check your remote filesystem- the idea is:
> unzip site-archive.zip
> rm -rf yoursite.net/site-archive.zip

visit us


Also, check out the evolving PSU Hacking Club wiki here!

xD  - Jess

Summer 2019 Update!

GIS Updates:

Newish Raster / DEM image → STL tool in the Shiny-Apps repo:

https://github.com/Jesssullivan/Shiny-Apps

See the (non-load balanced!) live example on the Heroku page:

https://kml-tools.herokuapp.com/

Summarized for a forum member here too:  https://www.v1engineering.com/forum/topic/3d-printing-tactile-maps/

CAD / CAM Updates:

Been revamping my CNC thoughts- 

Basically, the next move is a complete rebuild (primarily for 6061 aluminum).

I am aiming for:

  • Marlin 2.x.x around either a full-Rambo or 32 bit Archim 1.0 (https://ultimachine.com/
  • Dual endstop configuration, CNC only (no hotend support)
  • 500mm2 work area / swappable spoiler boards (~700mm exterior MPCNC conduit length)
  • Continuous compressed air chip clearing, shop vac / cyclone chip removal
  • Two chamber, full acoustic enclosure (cutting space + air I/O for vac and compressor)
  • Full octoprint networking via GPIO relays

FWIW: Sketchup MPCNC:

https://3dwarehouse.sketchup.com/model/72bbe55e-8df7-42a2-9a57-c355debf1447/MPCNC-CNC-Machine-34-EMT

Also TinkerCAD version:

https://www.tinkercad.com/things/fnlgMUy4c3i

Electric Drivetrain Development:

BORGI / Axial Flux stuff:

https://community.occupycars.com/t/borgi-build-instructions/37

Designed some rough coil winders for motor design here:

https://community.occupycars.com/t/arduino-coil-winder/99

Repo:  https://github.com/Jesssullivan/Arduino_Coil_Winder

Also, an itty-bitty, skate bearing-scale axial flux / 3-phase motor to hack upon:

https://www.tinkercad.com/things/cTpgpcNqJaB


Cheers-

- Jess

Deploy Shiny R apps along Node.JS

Find the tools in action on Heroku as a node.js app!

https://kml-tools.herokuapp.com/

See the code on GitHub:

https://github.com/Jesssullivan/Shiny-Apps

After many iterations of ideas regarding deployment for a few research Shiny R apps, I am glad to say the current web-only setup is 100% free and simple to adapt.   I thought I'd go through some of the Node.JS bits I have been fussing with. 

The Current one:  

Heroku has a free tier for node.js apps.  See the pricing and limitations here: https://www.heroku.com/pricing as far as I can tell, there is little reason to read too far into a free plan; they don’t have my credit card, and thy seem to convert enough folks to paid customers to be nice enough to offer a free something to everyone.  

Shiny apps- https://www.shinyapps.io/- works straight from RStudio.  They have a free plan. Similar to Heroku, I can care too much about limitations as it is completely free.  

The reasons to use Node.JS (even if it just a jade/html wrapper) are numerous, though may not be completely obvious.  If nothing else, Heroku will serve it for free….

Using node is nice because you get all the web-layout-ux-ui stacks of stuff if you need them.  Clearly, I have not gone to many lengths to do that, but it is there.

Another big one is using node.js with Electron.  https://electronjs.org/ The idea is a desktop app framework serves up your node app to itself, via the chromium.  I had a bit of a foray with Electron- the node execa npm install execa package let me launch a shiny server from electron, wait a moment, then load a node/browser app that acts as a interface to the shiny process.  While this mostly worked, it is definitely overkill for my shiny stuff.  Good to have as a tool though.

-Jess

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