Itās just not fair. Thereās always too much to do. Everyone just keeps piling more work on me. I feel so helpless.
Category: Blog
Raspberry Pi Whole Home Audio: Playing Music
Itās very rare that I tweet teasers to my blog post, but
last weekend I was so excited to be making progress on my Raspberry Pi Whole
Home Audio project that I told the world Iād be publishing this one on
Thursday.
DIY #RaspberryPi Whole Home Audio system is progressing! Latest blog post coming Thursday… http://t.co/0FaPcSeDEc pic.twitter.com/syEMoG24Gm
ā Jason Williams (@JayWll) February 9, 2015
Here we are on Friday morning. Thereās doubtless a lesson in
here for me about making promises I canāt keep, but Iām hoping youāll forgive
me when you read about what Iāve done.
If youāve been following my #RPiWHA Project
hashtag on this blog then youāll know that when we left off last time I had
three Raspberry Pis networked together with synchronized clocks, and one of
them had access to the internet and the music library I keep on my home server.
Thatās important, but not especially exciting. Today weāre going to move in a
more exciting direction, though.
Today weāre going to put Pis #2 and #3 aside, but weāre
going to get Pi #1 playing music!
Specifying and Testing the Piās Audio Output
The Raspberry Pi has two options for audio output. It has a
3.5mm analog output, and digital output through its HDMI port. It decides which
output to use automatically ā if you have a HDMI monitor plugged in then the Pi
will detect this and assume you want to use HDMI for audio too.
Thatās not the situation for me (my Pi is āheadlessā and
doesnāt have a display connected at all), and audio comes out of the 3.5mm
output automatically ā which is what I want. If you need to specify, you can
run:
sudo amixer cset numid=3 1
The digit 1 at the
end means the Pi should use the analog audio output. Putting 0 there instead would mean auto-detect
(the default) and putting 2 would
mean digital output over HDMI.
Plug in some headphones or speakers and run:
aplay /usr/share/sounds/alsa/Front_Center.wav
You should hear a voice saying āfront centre.ā
Install Mopidy
Weāre going to install music playing software called mopidy.
It provides a web-based interface so you can control your music, or there are
controller apps available in your app-marketplace of choice. Mopidyās website
takes you through the
install process in detail, but Iām going to summarize the commands here:
wget -q -O - https://apt.mopidy.com/mopidy.gpg | sudo apt-key add - sudo wget -q -O /etc/apt/sources.list.d/mopidy.list https://apt.mopidy.com/mopidy.list sudo apt-get update sudo apt-get install mopidy python-setuptools
Done! We now have a basic install of mopidy, and the especially
astute amongst you will have noticed that weāve also installed a package called
python-setuptools. Mopidy is written
in the python programming language, and the latter package is going to help us
with installing and setting up some mopidy extensions in an automated way. The
first thing weāre going to do is install something called pip, which is a tool for installing python packages:
sudo easy_install pip
Now that we have that, weāre going to in turn use pip to
install some mopidy extensions:
sudo pip install Mopidy-MusicBox-Webclient sudo pip install Mopidy-WebSettings
With those commands weāve added a web-based interface to our
player so we can control it from a browser on another computer or mobile
device.
Setting Up Mopidy
Weāre almost ready to start mopidy and try things out, but
there is a little bit of initial setup to be done first. Edit the file ~/.config/mopidy/mopidy.conf. In the http section, change the following line
so that the web interface becomes accessible to any device on your network:
hostname = ::
In the local
section, tell mopidy where it should find your music library. In my case:
media_dir = /mnt/music
Save the file and exit. The next step is to tell mopidy to
scan your music folder:
mopidy local scan
If, like me, you have a large music collection stored on a
network share, be prepared for this to take a very long time. I started it
running before I went to bed, and it eventually completed the process about 45
minutes after I got up the following morning.
When itās done though, weāre ready! Run mopidy:
mopidy
Itāll take a little while to fully start up, but when you
see the line
INFO HTTP server running at [::]:6680
that means weāre good to go. Open the browser on your
computer or mobile device and point it to
http://192.168.1.71:6680/musicbox_webclient (replace 192.168.1.71 with the IP
address of your Pi as appropriate). Go to Browse, Local Media, and select a
song!
If all is well the music will be playing through the
headphones or speakers attached to the Pi, and weāre all done until the next
installment ā rerouting the audio from Pi #1 and streaming it, synchronized, to
Pis #2 and #3 instead.
Enjoy!
Permission to Lead
At the office I so rarely visit I have a quote that Iāve
printed and pinned to the wall. It comes from Rear Admiral Grace Hopper, who was a
U.S. Naval officer and an early computer programmer (she developed the first
compiler for turning source code into object code).
In a couple of my recent
posts
Iāve made mention of a cultural evolution thatās underway in my workplace. Itās
not a revolution ā itās us collectively choosing to be much more deliberate
about using the values we already hold to better deliver benefit to our
customers. As a part of that weāve defined ten core values, or mantras, or
whatever you want to call them. I donāt know whether or not my employer would
want me to reveal them in a public forum like this. Probably not yet, at least,
given that the evolution is in its infancy: weāre still in the process of socialising
them internally and defining what they mean to each of us individually, to our
workgroups and teams, and so on. In lieu of the ones from my organization, hereās
an example of a similar-in-spirit core value from
another company (Zappos.com):
- Do more with less
Today one of my colleagues and I were talking about our ten
and poking some gentle fun at them. We were coming up with a handful of jokey
possible additions:
- Try turning it off and back on
- āThatās what she saidā
Anyway, I said that āitās easier to ask forgiveness than it
is to get permissionā should be added to our list. I was joking. But should I
have been?
I like Grace Hopperās quote so much because, on the face of
it, itās about rebelliousness and lack of respect for authority. Thatās
typically someoneās immediate takeaway when they first read it, and those are
qualities I like to pretend I have. Except I donāt, really ā I pretty much do
what Iām told.
Itās been a good while since I printed that and first pinned
it to the wall of my cube, though. Iāve gained some seniority in that time, and
as I was thinking about this today it occurred to me that nobody really tells
me what to do anymore. My leaders set direction, provide clarity around whatās
important (and why) where necessary, provide guidance where I need it, and then
they trust me to do whatever it is that I do.
Dig just very slightly beyond the surface of Graceās quote,
and this is, Iām sure, exactly what she was talking about. Grace was, after
all, a senior military officer: I highly doubt she was advocating for a lack of
respect for authority. What sheās talking about is ownership, and
accountability. Sheās saying that if you donāt have the necessary autonomy to
demonstrate those qualities then thatās a problem so serious that you should be
taking immediate action. If thereās red tape or dumb business rules that are a
barrier to doing what you know to be the right thing then you absolutely need
to be finding a way through it, and sooner rather than later. I think thatās
something worthy of inclusion in any organizationās core values.
Thinking about all this also got me thinking back to how the
quote became words that I choose to live by in the first place. A couple of years
ago I worked at my companyās call centre, on a team responsible for operations
and process improvement initiatives. I used to provide coaching to a handful of
junior teammates. From time to time we would identify an opportunity for
improvement in one of the ancillary, supporting business processes, but being a
process on the edge of the core business weād sometimes struggle to find
someone from the key leadership to identify as owning the process and provide
sponsorship for improvement. Iād always provide the same wisdom: āIf thereās
one thing Iāve noticed about where we work,ā Iād say, āitās that if you act
like youāre in charge of something then youāll very quickly find that you are.ā
I think at the time I thought I was joking about that too,
and that little running joke is what led me to first put Graceās quote up on
the wall. Even if I did think it was a bit of a joke though I did endeavour to embody
those words, and with the benefit of reflection it now seems as though Iāve advanced
my career since then in part off the back of simply acting like Iām in charge
of stuff. Interesting.
Really though, this shouldnāt be surprising. My vocabulary
has become more sophisticated in that time too: I now see more clearly that āacting
like Iām in charge of stuffā is just a slightly tongue-in-cheek synonym for our
theme of ownership and accountability.
Once upon a time I used to wonder to myself why merely
acting like I was in charge of stuff so often proved to be such a powerful tool
in my toolbox. When you frame it in those more sophisticated terms the answer
is clear. The reason it worked so well at my workplace is because we have a
culture that recognizes, values and rewards leadership attributes like these no matter the level of the employee they come from.
The question I should have been asking is why wasnāt it like that at previous
companies Iāve worked for?
Thankfully, the answer to that one doesnāt matter to me
anymore.
Social Networking at the Office
In mid-January Facebook hit the headlines with (and receivedĀ decidedly mixed reviews on) the announcement of their āFacebook at Workā offering,
which is essentially a walled-garden version of Facebook with access restricted
to those in your company. Aside from that important distinction the list of
features seems pretty much on a par with the larger Facebook we all know.
With this product offering Facebook joins an enterprise
social network marketplace that already contains some big names: Microsoft,
IBM, Cisco and SAP amongst them.
I can see the benefits of these platforms in terms of
collaboration, messaging, and the like ā but Iām certainly glad that my
responsibilities donāt include the realization of those benefits for my
company. The scope of the behaviour change required to make the most of those
tools falls into the category of āculture shiftā in my mind, and that stuff is simply
not where my expertise lies ā itās a task that goes way beyond technology and
business process folks like I.
Where I work, weāre now on our second enterprise social
network. Weirdly, the first one hasnāt actually gone away ā everyone has simply
stopped talking about it (and we all stopped using it long ago). The
implementation of the first one ā I feel ā was probably driven by technology
folks. I say that because from a technical perspective it works great, but
nobody ever told me what it was for. Apparently Iām not alone in my confusion,
because it never really saw any significant usage.
Things are looking a little better for the new one. For one,
itās integrated into our enterprise learning environment. At first that seemed
weird to me, but now that I think about it that makes perfect sense: learning
and development in the modern enterprise is increasingly something you do at
your own pace (to a certain extent), in your own office with the door closed
and headphones on. Itās crying out for something to bring back some of the
social aspects that are lost now that technology has begun to make
classroom-based training sessions a thing of the past, and I hope our training
teams pick up this ball and run with it. Additionally, thereās a movement
underway to build on our corporate culture and do a better job of leveraging it
for the benefit of our customers. Open, social communication that transcends
our geography is an important part of that cultural evolution too. The time is
right, then, for a platform to make this happen.
Nevertheless, people were burned by the failure of our
previous platform to gain traction, and thereās a healthy amount of skepticism
out there. Again, nobody has really told me what the new platform is for or
given me examples of how I could use it to my benefit.
A quick conversation with my boss about this last week
brought me to an important realization. Why am I waiting around for someone to
tell me what this platform is for? Iāll decide what itās for! Iām even starting
to think the lack of guidance and instruction might be a deliberate choice made
in the interests of organic growth and buy-in fuelled by self-realization
(although, frankly, I still think itās the wrong choice if thatās the case).
I plan to encourage my team to shift some of our non-time
sensitive group communication out of Outlook and into the social space, and I
sincerely hope it catches on. I think that would be a good starting point for
us, and as I said at the top, I really do see the benefits of a platform like
this. Iām putting my own skepticism firmly aside in the interests of trying to
steer my group toward the realization of those benefits that this platform
could represent. Weāll see how it goes!
Hopefully I wonāt be around to see the
introduction of a third enterprise social network. I wonāt be so generous if I
am.
Browse Anonymously with a DIY Raspberry Pi VPN/TOR Router
So, after last week’s post about preparing my Raspberry Pis for my whole home audio project, I had three Pis that should have been set up properly, but weren’t working very well – and the culprit was the USB WiFi dongles I was using.
Happily a stumbled upon the article linked above, and it solved the issues I was having!
Surf the Internet securely with your very own portable WiFi VPN/TOR router. You can configure a Raspberry Pi with Linux and some extra software to connect to a VPN server of your choice.
I didn’t follow all the steps because they’re doing something different to me, but there is some commonality and, crucially, the article folks are using WiFi adapters with the same chipset that mine have. Step four shows you how to download and compile a version of hostapd that’s built especially for them and works well. I’ve updated my previous post with these steps.
Now that I have networking all set up I’ve taken a couple of extra steps:
- I set up passwordless ssh between the three Pis. This isn’t required for my solution per se, it just makes things easier.
- I used sshfs on pi #1 to connect it to my existing home server, and mount the folder that holds all my music.
I’m excited to move on to next steps! The prep work was necessary, but it didn’t make for an especially interesting blog post because it’s all a bit dry.
Keep following my #RPiWHA Hashtag! The next installment will be more interesting, I promise. We’re going to get some actual music playing!
Raspberry Pi Whole Home Audio: Preparation and Networking
At the start of the month I announced my plan to try and build my own whole home audio system using a handful of Raspberry Pis to act as the player and audio
receivers. Iāve received
all the stuff I need now, and Iām ready to get to building!
The first thing Iām doing is preparing the Pis and setting
up networking. Next Iām going to install audio playing software with a
web-interface on Pi number one, and thirdly Iāll adjust the setup so that this
player sends itās audio to the other two Pis (the receivers) instead of
outputting it directly to its own speakers. You can follow the whole journey by
following the #RPiWHA
Project hashtag right here.
Installing Raspbian
Raspbian is the Raspberry Piās recommended operating system.
Thereās plenty of guidance online on how
to install it, so I wonāt reiterate the whole process here. When I ran
through Raspbianās initial setup options on first boot I set my location,
timezone and keyboard layout (in Internationalisation Options), set the memory
split to 16mb for graphics (in Advanced Options ā we can set this low because
we wonāt even be connecting a display) and finally expanded the filesystem
(right from the main menu).
Minimizing SD Card Access
The Pi has no power button. If itās plugged in then itās on,
and you turn it off by pulling the plug. Iāve read online that if the power is
pulled while the system is in the process of writing to the Piās SD card (which
is the only storage the system has) this can cause problems and possible
corruption.
Linux systems do a lot of logging, most commonly to the
folder /var/log. They also write stuff about running process to the folder
/var/run. To minimize writes to the SD card, weāre going to mount these two
folders in memory instead of on the card. Another cause of frequent writes is
that linux systems store the time that a file was last accessed, so even if weāre
just reading a file the system is actually writing back to the disk to update
the time that the file was accessed. Weāre going to change that behaviour too.
To make these changes, weāre going to edit the file
/etc/fstab so that it looks like this:
proc /proc proc defaults 0 0 /dev/mmcblk0p1 /boot vfat defaults,noatime 0 2 /dev/mmcblk0p2 / ext4 defaults,noatime 0 1 none /var/run tmpfs size=1M,noatime 0 0 none /var/log tmpfs size=1M,noatime 0 0
The first two lines havenāt changed, but on the third line
weāve added the flag ānoatimeā to indicate that we donāt want to store the
timestamp that the file was last accessed. The fourth and fifth lines are
entirely new, and these create 1mb partitions in RAM to house the /var/run and /var/log folders respectively.
Setting Up Networking on Pi #1
The next step was to connect one of the Pis (and only one)
to my existing home WiFi network. To do this I plugged in one of my USB WiFi
adapters and modified the /etc/network/interfaces file to include the
following:
auto wlan0 allow-hotplug wlan0 iface wlan0 inet static wpa-ssid MyHomeWiFiName wpa-key-mgmt WPA-PSK wpa-group CCMP TKIP wpa-pairwise CCMP TKIP wpa-psk MyHomeWiFiPassword address 192.168.1.71 netmask 255.255.255.0 gateway 192.168.1.254 dns-nameservers 192.168.1.53 192.168.1.254
Your setup will probably be slightly different, but
essentially this connects to my home network, gives the pi a static IP address
(192.168.1.71 in my case) and defines my two DNS servers.
You may be wondering why Iām only doing this on one of the
Pis, given that they all need to be connected together. The reason is that this
first pi (the player) is ultimately going to be sending audio out over the
network as multicast packets. In other words, this data goes to every device on
the network whether they want it or not.
The problem is that this is a lot of data flowing around, and
a typical home WiFi network struggles under the load of it all. My solution is
to have two WiFi networks. The one weāve set up above will connect us to the
internet (for streaming audio services) and other stuff on my network (like the
fileserver where my music collection lives), but weāll use a second, separate
WiFi network to send the multicast audio to other Pis.
Letās plug in a second USB WiFi adapter to the first Pi, and
make some more additions to the /etc/network/interfaces file:
auto wlan1 allow-hotplug wlan1 iface wlan1 inet static address 192.168.5.1 netmask 255.255.255.0
This section is pretty minimal as you can see, but itās
setting a static IP address on the second wireless interface. The important
part is that this uses a different subnet to the other WiFi network (in my
case, 192.168.1.x is my existing network, 192.168.5.x is the dedicated network
for the Pis).
This section of the /etc/network/interfaces file is so short
because this Pi is going to act as a wireless access point that the others will
connect to. To set this up we need an additional bit of software, called
hostapd. Because I’m using WiFi adapters based on a Realtek 8188 chipset, I had to download and compile this myself – the version found in the debian software repositories wouldn’t work for me:
wget https://github.com/jenssegers/RTL8188-hostapd/archive/v1.1.tar.gz tar -zxvf v1.1.tar.gz cd RTL8188-hostapd-1.1/hostapd make sudo make install
Then edit the file /etc/hostapd/hostapd.conf to change the following three lines:
interface=wlan1 ssid=PiWHA wpa_passphrase=mySecurePassword
Finally, start the service and add it to the boot autostart services for future:
sudo /etc/init.d/hostapd start sudo update-rc.d hostapd enable
Setting Up Networking on the Other Pis
We want the other Pis to connect to the wireless network
hosted by Pi #1. To do so, plug one USB WiFi adapter into each and modify the
/etc/network/interfaces file on each to reflect the following:
auto wlan0 allow-hotplug wlan0 iface wlan0 inet static wpa-ssid PiWHA wpa-key-mgmt WPA-PSK wpa-group CCMP TKIP wpa-pairwise CCMP TKIP wpa-psk mySecurePassword address 192.168.5.2 netmask 255.255.255.0
The important point here is that the IP address for each
must be unique, and must be on the same subnet (192.168.5.x) that we set on the
first Pi.
Setting Up Time Synchronization
The Raspberry Pi has no real-time clock, and instead it gets
the time from internet time servers at boot. Having the time synchronized on
each of our Pis is going to be important to make sure that they play music in
sync. Only the first Pi has a connection to the wider internet though, so we
need to take some additional steps. On Pi #1, edit the file /etc/ntp.conf and
uncomment (or add) the following line:
broadcast 224.0.0.1
This tells the pi to broadcast a time signal out onto the
network using a special multicast IP address that the other Pis will listen
for.
On the other Pis edit the same file, but uncomment (or add)
the following lines:
disable auth broadcastclient
We donāt need to tell the other Pis which multicast IP
address to listen for ā they already know as part of the NTP protocol.
And Weāre Done! Or Are We?
That was a lot of setup work, but we should now have our Pis
setup and networked together, with our player device having an additional
connection to the wider internet.
The thing isā¦ I donāt. The setup is all correct, but the
cheap USB WiFi adapters I bought from China donāt properly support access point
mode. Sometimes things work, sometimes they donāt.
Iāve read that I can download driver source-code from the
adapterās manufacturer and compile the driver myself, so Iām going to try this
before I go further.
If you’re a regular reader you may or may not have already guessed that I typically write these posts in advance and then set them to publish on a schedule. It’s not really a hard and fast rule, but if I have a couple of posts to publish in a week then I’ll usually schedule them on a Tuesday and a Thursday at the start of the workday here in the Mountain timezone so that they catch the end of the workday in Europe.
The reason I mention this is because the post I published yesterdayĀ āĀ Voicemail: A Beginner’s GuideĀ ā was actually written last Sunday before I left for my business trip. As it turns out it was extremely prophetic because I spent Tuesday and Wednesday with other leaders from my workplace talking about our culture and how we become better at leveraging the values we already hold, ensuring that the work we do for our internal customers (all my customers are internal) translates correctly and has a positive impact on our end-user customers.
The session was excellent and hugely valuable, and I’m not doing it justice in my description.
I mention it mostly because the overuse of email and the underuse of the phone became something of a common theme, as did intentionality and using your own behaviours to drive the right behaviours in others.
Great minds think alike, hey?
If you’re a regular reader you may or may not have already guessed that I typically write these posts in advance and then set them to publish on a schedule. It’s not really a hard and fast rule, but if I have a couple of posts to publish in a week then I’ll usually schedule them on a Tuesday and a Thursday at the start of the workday here in the Mountain timezone so that they catch the end of the workday in Europe.
The reason I mention this is because the post I published yesterdayĀ āĀ Voicemail: A Beginner’s GuideĀ ā was actually written last Sunday before I left for my business trip. As it turns out it was extremely prophetic because I spent Tuesday and Wednesday with other leaders from my workplace talking about our culture and how we become better at leveraging the values we already hold, ensuring that the work we do for our internal customers (all my customers are internal) translates correctly and has a positive impact on our end-user customers.
The session was excellent and hugely valuable, and I’m not doing it justice in my description.
I mention it mostly because the overuse of email and the underuse of the phone became something of a common theme, as did intentionality and using your own behaviours to drive the right behaviours in others.
Great minds think alike, hey?
Voicemail: A Beginnerās Guide
This week Iāve been travelling for work. I left Calgary early Monday morning, and I returned home late last night.
On Sunday night as I was preparing for my trip I briefly considered setting an āout of officeā email alert and changing my outgoing voicemail message to advise people of my unavailability. I quickly dismissed this plan though, for the simple reason that I really wasnāt all that unavailable. Sure I was away from my physical desk in Calgary, but I rarely work from there anyway. And sure my calendar was full, but thatās not unusual either. Setting up unavailability alerts would have been a misuse of the tools available to me.
As I was thinking about all this, it put me in mind of a post I wrote about seven months ago titled Weird Workplace Etiquette. In it, I complained about the fact that nobody just picks up the phone and calls me without first sending me a message (or worse, booking some time in my calendar) to ensure that Iām going to pick up the phone and talk to them.
Now that Iāve had some time to think about it, the reason seems obvious to me. We can lay blame firmly on voicemail. Subconsciously or otherwise people hate it, because everybodyās had a bad experience with it. Think about how it normally goes between a couple of busy people ā you leave a voicemail for me in which you ask me to call you back, I call you back and get your voicemail, and so it continues ad infinitum.
Happily, this is pretty easy to fix in my opinion, and the ROWE course I took not too long ago teaches us the way: itās merely a matter of breaking some bad voicemail habits that almost everyone has. Even more happily, you (mostly) donāt need other people to read my advice ā you only need concern yourself with what you do. If you do it right, others should fall into line.
Read on to get started!
Everything starts with your outgoing voicemail message. What does it say now? I assume itās something along the lines of āIām sorry Iāve missed your call, please leave me a message and Iāll get back to you.ā To be blunt, thatās not good enough.
Firstly, youāre not sorry youāve missed somebodyās call. You were busy doing something more important than picking up the phone, and thatās OK! Apologising for it is a meaningless platitude and everyone knows it, but more importantly it sets the wrong tone for what weāre trying to accomplish. Youāre a (wo)man of action, not the kind of person who spews forth wet apologies for failing to be idly sitting around by your phone when somebody somewhere kind of vaguely hoped thatās what you might be doing. If anything, you should apologise when you are available to answer the phone!
Instead, your outgoing voicemail message should reflect that yes, you were too busy to take the call and also yes, youāre too busy to engage an endless game of phone-tag. Instead of asking callers to leave you āa message,ā be specific about what youāre looking for from them.
āYouāve reached Jason. Please leave a message detailing how I can help you and by when you need a response, and Iāll get back to you as appropriate.ā
The same goes for when youāre leaving a voicemail for somebody. Just because their outgoing message is vague doesnāt mean the message you leave for them should be too. Think about how you want somebody to react when they listen to your message. Do you want them to immediately get to work on what youāre asking of them, or do you want them to have to call you back and speak with you first so they can find out what you needed? Tell them what you want, and tell them to get back to you once they have it!
Iāve been using these tips for a little while now and I have to say theyāre working well for me. Voicemail is a vastly improved experience as a result ā although itās still under-utilised, because people still do all they can to avoid using the tool at all if they can at all help it. Most people never even get to hear my outgoing message and come to the realisation that Iām changing their lives for the better.
Regardless, the more I think about it the more I think I may actually kick things up a notch. Long-time readers may recall another post on this blog from the distant past in which I talked about how people (me) canāt possibly hope to read, understand and respond to every email they get in as timely a fashion as they might like. Email, in a typical workplace (certainly in mine) is a vastly overused tool. Voicemail, though? Thanks to everybody shying away from it, a voicemail is out of the ordinary and will get somebodyās attention. If I can do voicemail well, it could become a fantastic method for making my messages to people a higher priority than everyone elseās.
All Iāll have to concentrate on is not using it for evil.
The Punctuation Guide
About a month ago I posted about The Data Visualisation Catalogue. If you have data to visualise, hit up this website, tell it what you’re trying to show, and it will suggest some appropriate chart/graph types.
Today I’ve come across another single-purpose website that I think is great, and it’s audience is intended to be a little more general than people who want to visualise their datasets.
It’s The Punctuation Guide!
When I discovered it I fully expected not to learn anything new, merely to receive confirmation that my use of punctuation was already top-notch.
I was, of course, incorrect.
Check out the site to see what you’ve been doing incorrectly your whole life! One word of caution: the guide is intended primarily for writers of American English. There’s a page that explains the main differences between that and British English. Here in Canada you should probably be doing something in-between the two, but if you’re looking for specifics I’m the wrong person to ask.