Custom Counter

Circular Knitting Machine

This all started when my wife started to use a circular knitting machine that she purchased recently. These machines can be used to quickly knit hats, scarfs, slippers, etc. I have seen her creating yarn goodness within a matter of minutes. The machine certainly decreases the time to produce goods when compared to traditional hand knitting by several folds. As a toy, literally, it has proven its worth several times over.

Microswitch placement

While using the machine, she has found that keeping count on the number of times the machine has revolved can be somewhat challenging. Of course this situation created a need for an electronic counter.

The idea is to use a microswitch to detect the notches on the machine, and use an ATMEGA328P microcontroller (MCU), running at 16MHz, to keep track of the count. The MCU is the same used by the famous Arduino hobby board.

Installing the Boot Loader to an ATMEGA328P

I setup a Raspberry Pi workstation and installed the Arduino IDE on Raspbian. Using a simple circuit described here. I was able to install the boot loader and program a generic ATMEGA328P chip using an Arduino Uno board.

The next step is to create a simple Arduino sketch that keeps count on the number of times the microswitch has been pressed. I also enhanced the sketch to track each press as a “tick” and have the ability to remember how many ticks make a single revolution of the knitting machine. In this fashion, the counter can be used on different sizes of circular knitting machines. The goal is to count both the number of ticks and the number of revolutions knitted so far.

Prototype the circuit
Perfboard example

The circuit is then prototyped on a breadboard with an LCD display (LCD 1602). This was the easy part. The hardest part is to solder everything on a perfboard and then design a suitable 3D printed case.

It took many tries on the 3D printer to get certain tolerance right. Finally, putting everything together we get this:

Working counter integrated with the knitting machine!

I have to say that this work was super satisfying. As a bonus, the counter can work with any type of sensors or switches that act as Normally Open (NO) and closes when it detects or closed respectively.

As a learning process and an experiment, I would like to create a simple PCB with JCLPCB. However, I have yet to start on that yet.

PlexConnect with Apache 2

To get Plex working on my old Apple TV 3, I had to setup a PlexConnect server that bridges the Apple TV 3 to the Plex Media Server. Previously I discussed about hosting the PlexConnect server on a virtual machine (VM) because the host that PlexConnect is running on must be listening to port 80 and 443. Having a virtual machine is a big nuisance, because the VM may not be up and running. I even try to host PlexConnect on a dedicate Raspberry Pi so that I can leave it on, but that proved to be too slow.

I do have a Network Attached Storage (NAS) server so it will be ideal to run PlexConnect on that, but the NAS server is running Apache 2 which is already using port 80 and 443. Eureka! How about running a reverse proxy that points to an instance of PlexConnect running on the NAS that is running on a separate port. A quick Google search for the term “PlexConnect and Apache 2” found this page on GitHub. The article turned out to be extremely helpful.

I downloaded PlexConnect as before and created the certificates.

cd /home/kang


tar zxvf V0.6.tar.gz 

mv PlexConnect-0.6 PlexConnect

rm V0.6.tar.gz

cd PlexConnect/assets/certificates

openssl req -new -nodes -newkey rsa:2048 -out trailers.pem -keyout trailers.key -x509 -days 365 -subj "/C=US/"

openssl x509 -in trailers.pem -outform der -out trailers.cer && cat trailers.key >> trailers.pem

I then have to tell PlexConnect the following:

  • Do not enable DNS since we already have a DNS server running;
  • Do not enable automatic IP detection because it will get the wrong VPN client IP, instead I hard coded the IP;
  • Disable SSL server because this will be handled by Apache 2;
  • Change the port number from 80 to 18080

The final Settings.cfg configuration file looks like this with the changed values highlighted in bold:

enable_plexgdm = True
ip_pms =
port_pms = 32400
enable_dnsserver = False
port_dnsserver = 53
ip_dnsmaster =
prevent_atv_update = True
intercept_atv_icon = True
icon = movie-trailers
enable_plexconnect_autodetect = False
ip_plexconnect =
hosttointercept =
port_webserver = 18080
enable_webserver_ssl = False
port_ssl = 18443
certfile = ./assets/certificates/trailers.pem
allow_gzip_atv = False
allow_gzip_pmslocal = False
allow_gzip_pmsremote = True
loglevel = Normal
logpath = .

I had to configure my firewall’s local DNS to resolve to my NAS server, which is This was pretty simple on my UniFi Universal Secure Gateway (USG).

The Apache 2 configuration files needed to be setup with the reverse proxy for both port 80 and 443. To do this I added the following VirtualHost settings.

<VirtualHost *:443>

        SSLEngine on
        SSLProxyEngine on
        SSLCertificateFile "/home/kang/PlexConnect/assets/certificates/trailers.pem"
        SSLCertificateKeyFile "/home/kang/PlexConnect/assets/certificates/trailers.key"

	<Proxy *>
		Require ip

        RequestHeader set User-Agent AppleTV
        ProxyRequests Off
        ProxyPass / http://avs.localdomain:18080/ nocanon
        ProxyPassReverse / http://avs.localdomain:18080/
<VirtualHost *:80>
        SSLEngine off

	<Proxy *>
		Require ip

        RequestHeader set User-Agent AppleTV
        ProxyRequests Off
        ProxyPass / http://avs.localdomain:18080/ nocanon
        ProxyPassReverse / http://avs.localdomain:18080/

I also needed to enable the headers module.

sudo a2enmod headers

We then needed to create a new systemctl service for PlexConnect. I had to create a plexconnect.service file in /etc/systemd/system with the following contents.

 ExecStart=/usr/bin/python /home/kang/PlexConnect/

The final steps are:

  • Check the Apache configuration file
  • Restart Apache
  • Start PlexConnect
sudo apache2ctl configtest

sudo systemctl restart apache2

sudo systemctl start plexconnect.service

Went to the Apple TV 3, and reconfigure the DNS to auto, removed the old profile and re-add as the new profile. I discussed in my previous blog.

After signing into my Plex account, and testing various Plex media sources with the Trailers app, as well as trying out YouTube and the Prime Video app, everything is good! The VM is no longer required and we declare victory!

Plex on Apple TV 3

In my previous post, I talked about adding the Apple TV 3 to a value projector that I purchased on Black Friday. I was pretty satisfied with that solution, but then my ambition kicked in. Wouldn’t it be nice if the ATV3 can access my local Plex Media Server instead of streaming it from my iOS device using the Plex App via AirPlay?

A quick Google search yielded the discovery of the PlexConnect project. This is a very cool project. It allows the old ATV3, which does not support the native Apple TV Plex App, to act as a Plex client by spoofing the Trailers app that came with the box. To do this, the ATV3 needs to point its DNS network setting to a PlexConnect server, which performs the magic of bridging ATV3 requests to the Plex Media Server and handles the rendering.

PlexConnect was very easy to setup. I reused an existing Windows 10 virtual machine on my MacBook Pro for this purpose. My other servers in the house cannot be used because the required ports needed by PlexConnect are already in use. We cannot run PlexConnect on another port other than 80 and 443.

Changing the DNS settings on the ATV3 was straight forward, but adding the required profile of was interesting. The instructions for the profile were:

  1. Go to the AppleTV settings menu.
  2. Select “General” then scroll the cursor down to highlight “Send Data To Apple” and set to “No”.
  3. With “Send Data To Apple” highlighted, press “Play” (not the normal “Select” button) and you will be prompted to add a profile.
  4. Enter (without the quotes): “”

Once the above is done, all apps on the ATV3 including Prime, YouTube, etc. will not work without having the PlexConnect server up and running. Another note is that I had to run PlexConnect using administration privileges on Windows, otherwise it will not be able to listen to the secure ports.

Having the virtual machine up and running to service Plex was a bit bothersome. I setup another PlexConnect server on a Raspberry Pi to see if this can be an alternative solution, but it was just too slow with its 100Mbps network connection and its slow processor. It worked but the user experience was simply not good.

Perhaps the simplest thing is just to buy another Apple TV 4 during Boxing Day sale, and be done with it.

My ambition is still not fully met. My next step is to install a projector mount on the ceiling, so the projector is not taking up precious little desk space.

Apple TV with Projector

During the Black Friday / Cyber Monday weekend I performed an impulse buy and acquired a Vankyo V600 native 1080p projector for $280.49. The regular price for this unit is usually $399.99. I was curious what a big picture experience would be like on the flat wall of my curved staircase, which connects our main and second floors.

Projecting a Korean Variety Show (during Daylight)

The above end result was pretty impressive for the amount of dollars invested. I had an old Apple TV 3rd generation that was lying around not doing anything, and thought this would be a perfect media source for the projector.

Connection Layout

For good sound, a pair of Edifier 1850DB speakers, connected to an Airport Express, already existed upstairs. All I had to do was connect the Apple TV to the projector and set the Apple TV to AirPlay to the Edifier speakers. All of this worked as expected. However, I did run into a snag. The volume signals from the Apple TV was quite low. Even when I cranked up the Edifier volume, it was still barely audible. It took me a long time to figure out how to change the volume on the Apple TV.

Hidden Menu

Apparently when a video is being played on the Apple TV, you have to press and hold the select (centre) button on the remote until a menu shows up pertaining to subtitles, audio, and speakers. You have to select the speakers and find the AirPlay speakers that the Apple TV is using. In my case, the Edifier speakers were labeled as “Upstairs Speakers”. The volume controls are presented by the blue slider bar.

Now everything works as expected on my private Local Area Network (LAN). We can play YouTube, or any iOS apps that does video. However, it would be nice for guests to be able to AirPlay to the projector. With the holiday season fast approaching, our dinner parties could be spiced up with this idea.

After fudging around with my firewall setup, the old Apple TV is now accessible from our guest WiFi. Now anyone can literally and figuratively project a video source from their mobile device on to my huge wall upstairs.

I am super happy how this turned out. We’ll have to wait for the final verdict from our guests this holiday season.

Plug-in Economics for Prius Prime

According to Toyota, our new 2020 Prius Prime PHEV gets around 4.3L / 100km of city driving. We will use this number since it is not too far off of the combine driving number of 4.4L / 100km. This means at the time of writing this post, the current fuel price at our neighbourhood pump is at $1.15 / L. If you do some fancy math, the Prime will yield us 20.2km per dollar invested at the pump (20.2 km/$).

Ontario Electricity Costs (Fall of 2019)

As depicted by the chart on the right, in Ontario we have three tiers of charging rates. The Prime in the winter can do about 35km with a 9kWh battery. The exact numbers are 40km / 8.8kWh, but this is perfect condition, and we use some battery for heating the vehicle. This will yield us the following:


So by comparing the above numbers, it makes perfect sense to charge the vehicle during Off and Mid Peak hours, and not so much during On-Peak hours. However the On-Peak comparison is so close that if the mileage rating was at 4.5L/100km then it is a wash.

With a bit more fancy math, you can actually calculate how much does gas have to cost per Litre before On-Peak charges make sense. This turns out to be around $1.24/L.

Hopefully you find this information helpful.

Let’s Plug-In

On October 30th, 2019, we purchased a Toyota Prius Prime 2020, choosing the Upgrade trim without the technology package. We traded in our 2012 Toyota Sienna 8 passenger Minivan with approx. 90,000km for $11,000. After all the government incentives, fees, taxes, and dealer’s rebates, we ended up forking out less than $27,000 for the vehicle. The only thing we opted for was the rust protection device.

We now have this plug-in hybrid electrical vehicle (PHEV) for almost a week. The vehicle is very comfortable to drive, and much more refined than my 2013 Subaru Impreza. The Prius comes in three drive modes, Eco, Normal and Power. I find the Eco mode to be too slow and has too much accelerator latency. I prefer the Normal mode. The Power mode can be pretty fun especially when you have a fully charged battery.

There are plenty of YouTube videos and written articles already talking about how the car drives, and I agree with their positive take on the Prius Prime. Therefore, I won’t repeat what has already been said. I will focus on what impact the ownership of a Prius Prime has on our residential electrical consumption.

We have yet to invest in a level 2 charger (240V – 16A) for the house yet, so we are just using our regular 120V plug to charge the 8.8kWh battery for the vehicle. So instead of charging the vehicle in 2 hours with the level 2 charger, we find that it takes around 5 hours to fully charge the vehicle. Toyota’s charging specification is pretty dead on and accurate here.

I raided our utility company’s web site and was able to extract the following graphs. Either click on the image or this link to open the graphs.

The consumption graphs above points to a day with no electrical vehicle as a baseline, followed by three days of charging the Prius Prime in the evenings. It looks like charging the Prius only amounts to an average of 1.5 kWh increase from baseline per hour of charge. The graph shows about four hours of heavy charging follow by a lower power charge during the last hour and a half.

At the current off-peak rate of ~$0.10 per kWh, we are looking at about an increase of less than a $1 per day, and this gives you about a realistic 36km of pure EV mode (all electric) of range per charge. So for a month, $30 will give you around 1,000km of range!

We have driven the car for about 5.5 days, and racked up in excess of 300km. We still have 7/8 of a gas tank left, and the only reason why we used the gas is due to a test drive to the Toronto Premium Outlet mall in Milton. Otherwise our daily usage pattern, which consists of largely local errands, would allow us to just keep on using the battery.

Now the game is up. How long do you have to wait for me to update this blog entry when I fuel up our new Prius Prime for the first time? Watch and see, any wagers?

The Mechanics of Rights

Lately the phrase, “I have the right to …”, comes up a lot. Living in a society where basic and human rights exist and are protected and enforced by law is a good thing. These rights represent the rise of our social beliefs from savagery to civility, and encourage all of us to treat each other humanely.

We have long since conquered are basic needs, such as food, and shelter. Aside from members of our own species we do not fear any other species invading the security of our homes and families. We live largely in peace, and we argue and debate about things that really does not impact our basic needs. Instead, the things that we bicker about largely involve with how to improve our discretionary free time, such as:

  • How to make and spend money;
  • How to protect ones ownership and assets;
  • How to punish those who do not adhere to social norms;
  • How to maintain and climb whatever progress ladder that you want to climb;
  • How to change leadership;
  • Dream up new rights so that we can all be more comfortable;

We take for granted that it is this peaceful social atmosphere that allows us to contemplate how we can improve ourselves when living, working, and generally dealing with others. Without this basic-need social security blanket, all bets are off with rights.

I therefore assert that the notion of rights, whether they are human, civil, and even corporate are luxuries afforded by peaceful societies when they have enough time and sensibilities to create and enforce these rights. They are not a right but a privilege that we as a society has decided to define and maintain so that there is a higher sense of equality (protecting the weak from the strong), and civility.

Therefore it becomes very dangerous when people who would like to pursue new or change existing rights by adopting methods that endanger or violate the basic-need social security blanket. Radicals who justify the use of violence and threaten the basic social fabric and infrastructure to achieve their desire changes are also jeopardizing all other rights, threatening the livelihoods of others.

In essence, rights cannot be had, without peace and law. This is why I find very ironic that the people of Hong Kong are fighting for new rights by risking the current livelihood that others have enjoyed for so many years. Whether they know it or not, they are pursuing a path of country building and not protesting. Country building is much harder than instituting new rights. Many country’s foundation are ladened with blood and sacrifices.

Thoughts on the Hong Kong Protests

On the Maslow hierarchy of needs scale, Hong Kong currently share many of its basic needs with the mainland, including food, fresh water, and electricity. The end game of these protests should give due consideration to these geographical dependencies. Even if a political divorce is possible in the long run, it will be really difficult to live independently when you are still forced to share the same bed.

A symbiotic existence between Hong Kong and China seems to be unavoidable, as such finding common ground seems to be a better approach than inflammatory tactics based on hate and violence. The latter dehumanizes the opposition and ironically for all people of Hong Kong, erodes the one of the core values of a democracy, basic human rights. This is the same value that the protestors are advocating for.

Observing from recent history, it is really hard to pinpoint a country involved in the Arab Spring events that are better off now than before. Perhaps conciliatory talks can give rise to more creative possibilities of coexistence, and the elixir of democracy does not have to be the only arrow in the quiver to achieve peace and prosperity.

Leviton Decora Smart Dimmer with HomeKit

I purchased these DH6HD HomeKit compatible dimmer switches from Leviton from February of 2018 (over 1 1/2 years now).

When they work, they are great. BUT! My HomeKit app frequently report these switches with “Not Responding”. The only remedy that I know of is to remove the accessory and then re-add it again.

The process of adding the accessory is extremely frustrating and time consuming. Adding the accessory to the WiFi network is a hit and miss affair. It really is a crapshoot.

Today after three tries adding the Leviton without success, I almost gave up. Finally I discovered the following process in this reddit article. Even the technique outlined by the article did not work until I restarted the avahi-daemon.service on my Linux server, figuring that it may interfere with the Bonjour discovery process when adding the accessory.

Using the WiFi setup of the iPhone to add the Leviton device to the WiFi network definitely works smoother than using the Home app. Here are the steps:

  1. Reset the light switch by pressing and holding the on position of the switch until its LED light switches rapidly from red and amber. This can take more than 10 seconds.
  2. Set the iPhone to the appropriate WiFi network.
  3. Goto the iPhone WiFi menu, and you will the Leviton switch available for adding to the WiFi network. Add this device to the network.
  4. If an error is encountered when adding to the network, then restart the avahi-daemon service (or other mDNS service that may be competing).
  5. Once the switch is added to the network, proceed to add the switch with the Home app.

Apparently there is a firmware update for these switches. However, the update from 1.4.13 to 1.4.32 fail with the Leviton iOS app.

If you are thinking of getting a light switch for your home automation project, I would steer away from these switches!

DIY Garage Stereo with DML Speakers

I wanted music in my garage when I am cleaning my bike or doing some other work. However, I did not want to spend a lot of money but I also wanted to make sure that it sounded okay.

I was couch surfing one day and came across this YouTube video.

YouTube Video:
YouTube Channel: Tech Ingredients

The video talks about joining audio exciters to extruded polystyrene boards, traditionally used for insulation. I was intrigued.

I purchased a pair of DAEX25TP-4 by Dayton Audio from They look like this:

Dayton Audio DAEX25TP-4

I joined these exciters to FOAMULAR CodeBord Extruded Polystyrene Rigid Insulation which I purchased from Home Depot. I simply purchased a 24″ x 96″ and cut them in half so that I have a pair.

FOAMULAR CodeBord Extruded Polystyrene

Last I bought a cheap Lepy LP-2020A Class-D amplifier.

Lepy LP-2020A

I had an old Airport Express lying around which I can use as my source material by piping Apple Music through it. Here is the end result in my garage.

For less than $100, the sound is loud and good! The low end can be improved with a sub, but I won’t be doing that since this will be rarely used. The next step is to install some shelving and hide the wires so it is more presentable.