Fusion 360 On Mac

For the last year I've been using Fusion 360. Solidworks is too expensive for what I do, I haven't really liked Rhino or ViaCad, OpensCAD or FreeCAD. For the most part it works pretty good. There is however one problem I constantly encounter and that is the auto update mechanism leaves a lot to be desired. Chrome does this extremely well and I wish Autodesk would replicate their excellent system because at least once a month the Fusion 360 app either changes location in my dock or disappears completely. The disappearing completely is the biggest problem because then I have to go searching for it. Usually it lives here:

 /users/<username>/library/application support/autodesk/webdeploy/production/Autodesk Fusion 360.app

So hopefully this saves someone some time.

Raspberry Pi Overlay Root Filesystem

I copied this from https://yagrebu.net/unix/rpi-overlay.md so I don't loose it. I have done a lot of network booting and overlay file system work this last year and these are the best directions for overlay file system and don't want to loose them. I will rewrite them to include my own subtle changes at some point, and publish network booting and network booting + overlay file system (which is a total crazy mess with no directions).

Raspberry Pi Overlay Root Filesystem

This document describes a method to protect the root filesystem from writes while still allowing all applications to function as normal while writing to a temporary Overlay filesystem. Figuring this out would have been impossible for me without this excellent post by ejolson on the RPI.org forums.

For my installation I used a RPI 3 and the latest Raspbian Stretch Lite image (2017-11-29). I do not know if these instructions will work without modification on earlier RPI hardware.

Note: When the overlay filesystem is in place your RPI will function as usual, but any data generated after startup is only saved in RAM and will be lost upon reboot.

Let's Begin

First we need to create a initramfs image that contains the overlay module and a boot script to mount our root partition with the overlay. (All this could of course be compiled into the kernel image, but initramfs-tools(8) is an easier way to learn about the early init-process.)

echo overlay >>/etc/initramfs-tools/modules

Place the following boot script in /etc/initramfs-tools/scripts/overlay (download):

# Local filesystem mounting                     -*- shell-script -*-

#
# This script overrides local_mount_root() in /scripts/local
# and mounts root as a read-only filesystem with a temporary (rw)
# overlay filesystem.
#

. /scripts/local

local_mount_root()
{
        local_top
        local_device_setup "${ROOT}" "root file system"
        ROOT="${DEV}"

        # Get the root filesystem type if not set
        if [ -z "${ROOTFSTYPE}" ]; then
                FSTYPE=$(get_fstype "${ROOT}")
        else
                FSTYPE=${ROOTFSTYPE}
        fi

        local_premount

        # CHANGES TO THE ORIGINAL FUNCTION BEGIN HERE
        # N.B. this code still lacks error checking

        modprobe ${FSTYPE}
        checkfs ${ROOT} root "${FSTYPE}"

        # Create directories for root and the overlay
        mkdir /lower /upper

        # Mount read-only root to /lower
        if [ "${FSTYPE}" != "unknown" ]; then
                mount -r -t ${FSTYPE} ${ROOTFLAGS} ${ROOT} /lower
        else
                mount -r ${ROOTFLAGS} ${ROOT} /lower
        fi

        modprobe overlay

        # Mount a tmpfs for the overlay in /upper
        mount -t tmpfs tmpfs /upper
        mkdir /upper/data /upper/work

        # Mount the final overlay-root in $rootmnt
        mount -t overlay \
            -olowerdir=/lower,upperdir=/upper/data,workdir=/upper/work \
            overlay ${rootmnt}
}

Create the initramfs image:

update-initramfs -c -k $(uname -r)

It will be placed in /boot/initrd.img<kernel_version> - you can rename it to match your kernel file if you want.

Add the following to /boot/config.txt - where initrd7.img is the initramfs image you created in the previous step:

kernel=kernel7.img
initramfs initrd7.img

And finally, add boot=overlay to the beginning of /boot/cmdline.txt.

This should do it. Reboot and keep your fingers crossed.

Kernel Panic

If the OS doesn't come back up, there is probably a typo somewhere, or you missed something.

You can remove boot=overlay from cmdline.txt to boot as normal.

A serial connection can be really handy when trying to troubleshoot the startup process. USB TTL console cables are dirt cheap, just make sure you get one that outputs 3.3V on the TX line so that you don't fry your RPI. Use screen(1)'s buffer to scroll back and try to figure out where it went wrong.

The documentation is also quite good. Read the man page for initramfs-tools(8) and the default boot scripts themselves:

less /usr/share/initramfs-tools/init
less /usr/share/initramfs-tools/scripts/local

Finishing Touches

Read-Only /boot

The /boot filesystem is still mounted rw. You can protect it as well by adding ro to the boot partitions mount options in /etc/fstab:

PARTUUID=72a9e9a9-01   /boot   vfat   defaults,ro   0   2

overctl

Since I would be updating the filesystem on my RPI regularly, I wanted a secure way to enable and disable the overlay. overctl has the following features:

Usage: overctl [-h|-r|-s|-t|-w]
   -h, --help     This message
   -r, --ro       Set read-only root with overlay fs
   -s, --status   Show current state
   -t, --toggle   Toggle between -r and -w
   -w, --rw       Set read-write root

Place the script in /usr/local/sbin and mark the file as executable. You will also need to create the following files containing the cmdline.txt options that you wish to toggle between:

/boot/cmdline.txt.orig
/boot/cmdline.txt.overlay

motd(5)

I figured I could use a reminder of which state the RPI is in. So I cobbled together this motd(5) script:

#!/bin/sh

str=$(mount | grep ' on / ')

if echo $str | grep -q 'overlay'; then
        printf "\n------ INFO: / MOUNTED WITH OVERLAY ------\n\n"
elif echo $str | grep -q 'rw'; then
        printf "\n++++++ INFO: / MOUNTED READ-WRITE ++++++\n\n"
else
        printf "\n!!!!!! WARNING: / UNKNOWN STATE !!!!!!\n\n"
fi

Place the code above in /etc/update-motd.d/80-overlay and make sure the file is executable.

Sony vs Canon: DSLR and Mirrorless

I had the Sony A9 and AIII and just couldn't use them because they are way too small for my hands. I think there has been so much attention on mirrorless, as well as marketing money to influencers on YouTubers which makes it seem like everyone is using Sony. I get it, mirrorless has it's place, and there are some great features. there's also some terrible features. I currently use a number of Canon DSLR cameras including the Canon EOS R. The R isn't my favorite camera, but it has grown on me. Anytime I reach for a camera, certainly for traveling, that is what I bring 90% of the time. The R and a Canon 7GX MII has been with me to 4 continents over the last year and I honestly wouldn't trade them for any Sony, despite having access to them. So here is my list of pluses and minuses:

- Blackout: The A9 has no blackout, all other mirrorless cameras have way too much blackout in my opinion. Canon R blackout is better than any Sony other than A9 but impossible to oh take photos of whales because they move too fast. Any DSLR such as Canon 5D MIV work fine for sports and wildlife photography, I just don't get the complaining of DSLR blackout. A DSLR instantly refreshes, where a mirrorless displays the previous image for way way too long and then refreshes. Only the A9 is usable for any wildlife or sports photography period.

- In body image stabilization (IBIS) I really don't understand why everyone wants IBIS. IBIS actually is a detractor if you want a seriously durable camera because the sensor shakes around.

- Smaller bodies are good for small hands, but not good for big hands. I have tried every battery grip available for the A series and they just don't work. The new body design is better, but not even close to a Canon or Nikon. Also the grip is shallow enough and the lens release is at the base of the body so when I grab the camera I've released the lens more than a few times.

- Sony can't handle water. If a Sony looks at water it stops working. Where I have dropped my 1D in river water and they keep working.

- Sony has no service support. When a camera needs servicing Sony suggest throwing it away and buying a new one. Canon has CPS, which is awesome if you need a camera serviced. Absolutely ridiculous Sony. No professional can depend on a Sony because of this.

- Shake a Sony camera and it makes noise. Strange.

- Love Sony A9 silent shooting, amazing for Wedding photography. Absolutely a game changer.

- I like the flip out LCDs on Canon better than Sony. Also the touchscreen. The menu system on Canon is way better too. The video codec is a little better on Sony.

- Canon color science is the best there is. Nikon is actually really great too. Hasselblad is pretty awesome too. Sony, not so much, every photo and video needs to be adjusted to look good. But Nikon video is lacking.

- Weight. Anyone that tells me that a Sony weighs less is crazy. Put a comparable lens on both cameras and compare the weight, they are basically the same and actually the Sony weighs more, just with a tiny camera in your hands. If you put a super small lens on a Sony then you have a weight savings, but meh. Now size is a bit smaller for traveling which is nice. But go for a micro 4/3 if size is a real issue.

- What is really nice about mirrorless is there's a shutter release button for photos and a record button for video. You don't have to switch between modes and remember do I look through the eyepiece or the rear screen.

- Lastly, all camera's do their best autofocus in good light. However, mirrorless cameras have poor autofocus anytime the light is anything less than good. The reason for this is what you see is what you get, but that is also what you autofocus from, where a DSLR will flip the mirror down and open up the lens aperture, evaluate then flip everything back to take the photo. This can take time, but 16 FPS for the pro series and 5FPS for the low end is pretty darn good.

Get MAC Address for a Pi Cluster

There are a lot of ways to get the MAC address for a Raspberry Pi. For the Super Pi there were a lot of Pi, 1050 to be specific (two of them are dead on arrival and we disabled 24 of them to get the exact number we wanted, 1024), we looked at the DHCP log files. Roy and Mike spent a few days doing this. Think about it, if you spend one minute times 1050, that's 17.5 hours! I'm surprised they didn't go crazy but they seemed to be having fun. For the Mini Super Pi, I need to know the order.

At this point I'm going to digress a little. When building a large Raspberry Pi cluster at some point it's worth network booting. I'd say after 8 the cost of network booting is worth it. Just the time and expense of buying and cloning eight network cards. Network booting a Pi isn't terribly difficult, it's doing it consistently with a lot of them that's the problem. The netboot on a Pi times out after a short period of time, it isn't implemented 100% to spec, I could go on but these are things you can find out with some research. Although it's buried so if people want me to document these issues let me know in the comments. If there are any problems netbooting the Pi can be dead in a big cluster with no way to reboot it except reboot the entire thing. It helps to have a static IP address. Best way of doing this is by using DHCP (yeah, that's confusing) but map the MAC address to an IP address. Oh, also if you have enough Raspberry Pi, the MAC address may not be unique. We have two Pi with the same MAC addresses. Most clusters won't run into this. Also, network booting while not difficult requires the use of overlay file system. The problem comes when combining the two which is rather difficult. I got overlay file system working. Roy merged netboot and overlay and Vijay did this with Oracle Linux. There are a few other options netboot and redirect all writes to separate files and hope you got all them, create an NFS mount for each Pi (yeah, no). The only downside to netboot + overlay file system is you can't run Docker, which means you can't run K8 because Docker uses overlay and you can't use overlay on top of overlay.

OK, back to the reason for this blog post. My new system for obtaining the MAC address is as follows:

1. Install Raspbian on an SD card. I used belenaEtcher on Mac just because it's easy.
2. Copy the following Python script to the Pi and call it pimac.py

import socket

import time

import threading

import datetime

import uuid

import random

# This is needed so we get a network interface

time.sleep(20)

# Global variables

MacAddress = hex(uuid.getnode())

print(MacAddress)

print(type(MacAddress))

if MacAddress.endswith('L'):

    MacAddress = MacAddress[:-1]

    print(MacAddress)

client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP

client.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

client.bind(("", 2222))

server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)

server.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

server.settimeout(0.2)

server.bind(("", 3333))

hostname = socket.gethostname()    

IPAddr = socket.gethostbyname(hostname)    

print("Your Computer Name is:" + hostname)    

print("Your Computer IP Address is:" + IPAddr)

def SendMessage(port, message):

    data = message

    endodeddata = data.encode()

    server.sendto(endodeddata, ('<broadcast>', port))

    print("message sent!" + data)

while True:

    SendMessage(3333, MacAddress)

    time.sleep(2)

3. Create a cron job:

sudo crontab -e

4. Add this line to the end of the file:

@reboot python /home/pi/pimac.py &

5. Copy the following Python script to your desktop and run it. I'm running it in Visual Studio Code.

import datetime

import os

import signal

import socket

import threading

import time

import re

import uuid

if os.name == 'nt':

    signal.signal(signal.SIGINT, signal.SIG_DFL)

server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)

server.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

hostname = socket.gethostname()

IPAddr = socket.gethostbyname(hostname)

print("Your Computer Name is: {0}\n".format(hostname))

print("Your Computer IP Address is: {0}\n".format(IPAddr))

def waitForPosts():

  print('Ready')

addresses = {}

class Listen(threading.Thread):

    def __init__(self, port):

        threading.Thread.__init__(self)

        self.port = port

        self.UIDCount = 0

    def run(self):

        client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP

        client.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

        client.bind(("", self.port))

        while True:

            data, addr = client.recvfrom(1024)

            mac = data

            if mac not in addresses:

                addresses[mac] = mac

                val = mac.decode()

                print (':'.join(re.findall('..', '%012x' % int(val, 16)))) 

publish_thread = Listen(3333)

publish_thread.start()

waitForPosts()

Note: If you decide you want to remove the dictionary in the code above to allow duplicate MAC addresses to print out, which his a great debugging tool and since UDP is not guaranteed is a perfectly fine way to go, then you might want to remove duplicates. To do this in Visual Studio Code this is one way I found to do it:

1. Control+F
2. Toggle "Replace mode"
3. Toggle "Use Regular Expression" (the icon with the .* symbol)
4. In the search field, type ((^[^\S$]*?(?=\S)(?:.*)+$)[\S\s]*?)^\2$(?:\n)?
5. In the "replace with" field, type $1
6. Click  ("Replace All").

6. So now insert the SD card, plug the Pi into network, and power and wait. The output on your desktop will be a list of your MAC addresses in a known order and it is easy to know if one is dead and which one.

Shopify Payment System

It's a long story, but I have been dealing with an issue with Shopify for well over a year now. Many websites use them as their Payment system behind their merchant account. And they are very convenient, if one knew what they were getting into. Unfortunately there is absolutely zero disclosure on any of the websites that use it how this will work, how to edit your stored information or how to delete the data they stored. This is a direct breach of the GDPR, Informatique et Libertés as well as the new California data privacy law CCPA.

So with about a year of working with all of the merchants and Shopify support, I finally can report there is a way to opt out of Shopify:

https://pay.shopify.com/optout

Sparkfun MP3 Shield

SparkFun MP3 Player Shield

I have used a lot of these MP3 player shields in projects. They are super awesome and super simple to use, but I figured a small writeup was worthwhile as there are some details that aren't in the official documentation as well as some tips I have when using the shield.

The MP3 shield uses just about every pin on the Arduino. The documentation states you can use D5, D10 and A0-A5. However, I have found that for some reason when using the shield I have found neither D5 nor D10 to be usable. So typically what I do is setup a software serial using two of the analog pins:

#include <SPI.h>
#include <SdFat.h>
#include <SFEMP3Shield.h>
#include <SoftwareSerial.h>


SdFat sd;
SFEMP3Shield MP3player;

SoftwareSerial input(A0, A1); // RX, TX


void setup() {
  Serial.begin(115200);
  
  input.begin(9600);
  input.flush();

  if(!sd.begin(9, SPI_HALF_SPEED)) {
    sd.initErrorHalt();
  }
   
  if (!sd.chdir("/")) {
    sd.errorHalt("sd.chdir");
  }

  uint8_t result = MP3player.begin();

  if(result != 0) // check result, see readme for error codes.
  {
    Serial.println("error");
    Serial.print(F("Error code: "));
    Serial.print(result);
  }

  // Loudest volume for left and right
  MP3player.setVolume(0, 0);
  
  Serial.println("Ready");
}

void loop() {
  if (input.available()) {
    Serial.println("reading");
    String action = readFromSerial();
    Serial.println(action);
    input.flush();
  
    if (action == "play") {
      Serial.println("Playing"); 
      uint8_t result = MP3player.playMP3("awesome.mp3");
      delay(3000);
      Serial.println("Ready again"); 
    }
  }
}

String readFromSerial() {
  static char buffer[80];
  if (readline(input.read(), buffer, 80) > 0) 
  {
    Serial.println(buffer);    
  }
  return buffer;
}

int readline(int readch, char *buffer, int len)
{
  static int pos = 0;
  int rpos;

  if (readch > 0) {
    switch (readch) {
      case '\n': // Ignore new-lines
        break;
      case '\r': // Return on CR
        rpos = pos;
        pos = 0;  // Reset position index ready for next time
        return rpos;
      default:
        if (pos < len-1) {
          buffer[pos++] = readch;
          buffer[pos] = 0;
        }
    }
  }
  // No end of line has been found, so return -1.
  return -1;
}

Using Max Build Volume of Ultimaker 3D Printer

Sometimes you have to print at the max build volume of your 3D printer. You'll get the error: "does not fit build volume". I have an Ultimaker and the easiest slicer to use is Cura. And sometimes I want the full build volume of 330 x 240 x 300 mm. If you set the "skirt link count" to zero, it won't print the line around the part so you can get the full x and/or y. As you may know the reason for the skirt is so that the printer gets a consistent extrusion of the filament, but I you need the full bed size, then you need the full bed size. Also turn off brim and set build plate adhesion to "none". Lastly set "travel avoid distance" to 0. Do it in that order for best results.

Raspberry Pi Super Computer STL Files Published on Thingiverse

Finally. I'm sorry it took so long. Here it is, the files to print your very own 2U rack mountable Raspberry Pi holder for 21 Raspberry Pi 3B+. Let me know if you have any questions or problems. Just because we made over 50 of these, doesn't mean it's easy.

https://www.thingiverse.com/thing:3958586

Bringing Pi Home

Arduino Eithernet Shield 2 NTP Time

I'm trying to get an accurate time on an Arduino. I have an Ethernet Shield 2 attached to an Arduino Mega. There's also a couple current sensors and a barcode scanner. The main reason for this post is for those people that happen to have the Ethernet Shield 2 on any Arduino, and want to get the time. Every single example on the internet or in the Arduino IDE examples doesn't work, except for this one:

https://www.arduino.cc/en/Tutorial/UdpNtpClient

So as of the time of reading this, that tutorial will most likely be out of data, but let's say for the next 6 months it'll be the place to go.

So, here's a little insight into what I'm doing and my decisions along with some code at the end:

1. I have an Arduino. That means no clock.
2. I have an Ethernet Shield 2. That means there are an abundance of clocks on the internet.
3. I am not hooking up a clock to the Arduino. That means I need to use the Arduino to keep time.
4. So I'm going to do this by polling a clock on the internet, keeping that time around and adding the time since boot to that time. It isn't a clock you'd want to use as your morning alarm clock, but it'll be accurate enough for what I need.

So I hacked together two functions from that tutorial:

unsigned long getCurrentTime() {
  unsigned long result = 0;
  sendNTPpacket(timeServer); // send an NTP packet to a time server

  // wait to see if a reply is available
  delay(1000);
  if (Udp.parsePacket()) {
    // We've received a packet, read the data from it
    Udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer

    // the timestamp starts at byte 40 of the received packet and is four bytes,
    // or two words, long. First, extract the two words:

    unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
    unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
    // combine the four bytes (two words) into a long integer
    // this is NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;
    Serial.print("Seconds since Jan 1 1900 = ");
    Serial.println(secsSince1900);

    // now convert NTP time into everyday time:
    Serial.print("Unix time = ");
    // Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
    const unsigned long seventyYears = 2208988800UL;
    // subtract seventy years:
    unsigned long epoch = secsSince1900 - seventyYears;
    // print Unix time:
    Serial.println(epoch);
    result = epoch;
  }
  else {
    result = 2099414000; // Picked a date so we can test when not connected to the internet.
  }

  return result;
}

String timeToString(unsigned long value) {
    String result = "";
    unsigned long epoch = value;
    // print the hour, minute and second:
    result += String((epoch  % 86400L) / 3600); // print the hour (86400 equals secs per day)
    result += String('-');
    if (((epoch % 3600) / 60) < 10) {
      // In the first 10 minutes of each hour, we'll want a leading '0'
      result += String('0');
    }
    result += String((epoch  % 3600) / 60); // print the minute (3600 equals secs per minute)
    result += String('-');
    if ((epoch % 60) < 10) {
      // In the first 10 seconds of each minute, we'll want a leading '0'
      result += String('0');
    }
    result += String(epoch % 60); // print the second

    return result;
}

unsigned long startTime;

void setup() {
   // ...
   startTime = getCurrentTime();
}

And anytime you want the current time viola!

timeToString(startTime + millis() / 1000)

Fusion 360 - Threads Not Exported to STL

There is one thing that I always have problems with, so hopefully by writing this short blog post I'll remember more often. That problem is creating threads properly. Usually I noticed after I have already printed the part. Always remember to choose the "Modeled" check box. I wish I could make this the default.

Also, if you need to remove part of the hole after the threads in the timeline, you'll have thread remnants, so move the threads to be later in the timeline, then "Cut" the hole.

Very Large Raspberry Pi Cluster - Part VI

At this point I've shown how the all the Pi will be held in place to make a 2U rack, and next is the overall structure but that will have to wait until next week. So for this post I wanted to talk a little about the software and what we're going to run on all these Pi. A lot of data will be processed and sent to the cluster. So here's the high level of the software stack:

• Each Pi will network boot from a central server running Oracle Linux
• The boot image will be running Oracle Linux
• It will be running Kubernetes and Docker
• There will be a very large video wall run by a Windows server
• Everything will be written in Java
• Gluon is helping

What exactly it will do will remain a mystery until you come see it in person. So sign up for Code One and come see it!