Guest Commenting on codefoster.com

I just opened up guest commenting on codefoster.com.

I’m generally in favor of identity on the web and generally not a huge fan of anonymity. Pretty much every anonymous forum I’ve been to online is littered with the darkest parts of mankind. It’s a sad state really.

So consider this an experiment to see if anonymity will encourage good community on codefoster.com and if manual comment moderation is feasible and sustainable.

We’ll see. Please comment :)

The Regatta Project

My role at Microsoft is that of an evangelist, and that implies that we speak broadly to audiences about technology. Recently, however, my team is working one-on-one with organizations on exciting new Microsoft technologies - making sure they’re exactly what developers need.

One of the projects I’ve been working on recently is called Regatta championed by Baiyin Zhou (@baiyinvc) from Boston.

This entire idea is super fun. Imagine exercising on a rowing machine in a studio in a group session. Now imagine a visual on the wall depicting your rowing machine and those of the other session participants as real boats. As you heave and ho, you see your little boat moving across the screen.

There are just so many awesome scenarios that are possible at this point.

The visual of the boats alone is encouragement for you to work harder to compete against others in the class. But that’s pretty obvious isn’t it. What about the less obvious scenarios? What about being able to add in a phantom boat that represents the group’s average from yesterday’s workout? Now you’re not competing against your fellow rowers - you’re competing with them. You have to beat that phantom boat!

As soon as things in the real world - like our efforts to stay in shape - are digitized and turned into data, we get to do things like capture our progress, integrate with other fitness tracker systems, or even do data analysis to determine some deep learning from it.

This is the type of concept where digital systems really have an opportunity to affect our lives for the better. I keep saying that technology is not so interesting unless it improves our lives. For being such a technophile, I’m actually quite the skeptic, because all too often technology just gets in the way.

The Regatta Project envisions a future with a whole lot of rowing machines deployed with smart devices (the Raspberry Pi Zero at this point) attached to them, and assuring good communication with all of these devices is a great job for Azure IoT Hub.

Go check out the details of the [Regatta](https://microsoft.github.io/techcasestudies/iot/2016/12/10/regatta.html) project and let me know what you think with a comment below.

Regatta Architecture

5 More Posts

Blogging is a chore. Writing in general is a chore. It’s not easy to formulate thoughts and put them into words. I have a ton of respect for prolific authors that generate volumes in their lifetime, because that’s a phenominal feat.

I just looked at my blog statistics and I’m woefully low for the year. I have only blogged 14 times in 2016 so far. That’s barely over once per month, whereas I should be creating a post at least every week. I started off in 2012 with 87+ posts, and have tapered down to last year (2015) at only 19. I’m ashamed.

My desire is to write though. I write for you, my reader, but I certainly write for me too. It’s a great discipline and as any technical blog author knows, the main reason we post is to remind our future selves how to do something we at one point knew. Tell me you haven’t searched online for a technical answer only to find your own post from 2 years ago!

So here’s the deal. It’s currently December 8. There are about 23 days left in the year. My goal is to post at least 5 more times. Wait, this posts counts, so 4 more times. Hoorah! That’s completely doable and will mean that I have not digressed from 2015.

Furthermore, it’s my commitment to increase 2017 significantly. I won’t put any official commitments on a number out there, but there’s not reason I can’t maintain a weekly cadence and produce >52 posts for 2017.

Here we go!

A Month of Soylent

​I’ve been one month now on an (almost) exclusively Soylent diet.

Soylent is a drink engineered to be everything the human body needs for food. They don’t explicitly recommend that a person eats nothing besides Soylent, but they certainly don’t say it can’t be done, and there are plenty of folks that do it.

Soylent is billed as a “healthy, convenient, and affordable food”. In my experience, it’s quite easily all three. I’m pretty excited about this stuff.

Let me start by saying that I’m not a diet guy. I’ve made various attempts in the past to count my caloric intake, but I can’t remember the last time I imposed any kind of constraints on what I ate. In my opinion, counting calories sucks. It’s quite a chore stopping to think about what I’m eating, try to find its rough equivalent in a table somewhere, recording it, and trying to time the intake so that you end the day at the right number.

@kennyspade first introduced me to Soylent a full year ago. He brought the topic up in response to my mention of Mark Zuckerberg wearing the same attire each day to alleviate decision fatigue. Soylent is similar in its ability to eliminate the decisions we make about what we eat.

Kenny handed me a bottle of Soylent’s premixed product that they dub version 2.0 to try. I don’t remember being particular taken by the flavor or the texture, but I wasn’t turned off either.

Finally, the beginning of this September, I decided to try Soylent longer term, and I set my sites pretty high. I decided to reduce my diet to almost exclusively Soylent and water.

Soylent is available as a powder or a drink with the former being cheaper and the latter being more convenient. I opted for convenience for now.

I expected to be in for a bit of a personal battle. You see, I’m not that disciplined when it comes to eating. I’m basically just not accustomed to thinking about what I eat. I like sugar, so when candy is offered or available, I take it. If a bowl or a bag is offered, I take a few. I work hard and stay up late, so I drink coffee - perhaps 3 cups a day. And I like rich food in large portions. I was never overly excessive, but I haven’t been thrilled with my fitness either.

Well, it’s October now, so let me fill you in on my September…

Soylent is Tastier than I Thought

I started out not minding the taste, texture, and overall experience of Soylent 2.0 at all, but I ended up, somehow, absolutely loving it. Soylent tastes a bit like the milk left in your bowl after you’ve eaten Frosted Flakes, but a bit less sweet. I have a bottle every 4 hours, and after about 2 I’m really looking forward to the next one… not because I’m starving - I’m not - but because I enjoy the drink. The mouth feel is excellent too. It’s a little bit grainy in a good way, and I much prefer that to the overly thin texture I find in the other (usually milk-based) protein or meal replacement drinks I’ve tasted.

Soylent is Quite Filling

I decided to eat four 400 kcal Soylent drinks each day at 7am, 11am, 3pm, and 7pm. That’s 4 hours between meals and 1600 calories a day. The product is engineered to be 20% of the food a person needs for a day - 20% of the calories and 20% of the vitamins and nutrients - but I wanted to reduce my intake a bit and trim some fat.

After 4 hours of fasting, my stomach is ready for some substance, and whether I take my time drinking a bottle or throw it back in a hurry (in the TSA security line!) it does satisfy. I don’t feel full per say as I pitch the bottle into the recycle bin, but I don’t feel hungry either. I feel perfectly content for at least 2 hours and then start slowly getting hungry as I approach the 4 hour mark.

If I decided on a standard 2000 kcal diet, that would be 5 Soylents a day and a meal every 3 hours. That would be even easier.

Soylent is Easier than I Thought

The entire effort was much easier than I thought. I could hardly call it a battle, actually, as I initially thought it would be. The reason for this I attribute to the simplicity of my rule set…

  • I will eat only Soylent and drink only water
  • As a single exception to rule 1, if I get too hungry at any point, I’ll allow myself to eat broccoli. You can hardly go wrong with steamed, plain broccoli. It’s very healthy and doesn’t exactly pose a temptation.
  • If I have culinary social opportunities (team dinners, family outings, etc.) I’ll go and I’ll engage, but I just won’t eat. Believe it or not, you can still enjoy a conversation across the table from someone without eating. It grinds against habit perhaps, but it works. Admitted, it does take a little bit away from a romantic dinner, but actually, that’s a bit strange isn’t it? For some reason, it’s not as fun eating with someone when you’re doing all the eating. My wife was kind and accommodating though.

In previous attempts to eat well, I had to spend extra time considering each morsel that passed in front of me.

“Should I eat that cracker?”

“Should I eat a cookie?”

“Should I eat another cookie?”

“Just one more pretzel?”

“My own carton of fries or share with my wife?”

But this time it was different. The answer was always the same - “no”.

No soda. No coffee. No cereal. No cookie. No nothing.

No chicken, no carrots, no milk. No to seconds. No to firsts! No nothing. The answer is always no.

That greatly simplifies things and leaves my mind free to really concentrate on the project at hand or on what my 4 year old is trying to say to me.

Eating Includes a Lot of Ceremony

There’s a whole lot of ceremony around food that I wasn’t aware of until I got on the outside of it all.

Several time per day we think about food - we consider our hunger, we decide to eat, we decide what, we decide when, we decide where, we transport, we stand in line or wait on a server, we acquire, we consume, we ask to be excused while we chew and try to talk to others, and finally we clean up the mess on our table and on our hands. And after hardly any time at all, we start thinking about our next meal!

I also neglected to notice just how often we come up with the idea to find coffee. Is there a machine nearby? Is there a Starbucks nearby? And then again with the relatively long process of acquisition and consumption.

Food acquisition is still a cinch compared to ancient times when our food was running around with teeth. But the reality is that times are different and there may just be room for some efficiency improvements.

Recreational Eating Rocks

I wonder if you’re thinking, “Yeah, but I like eating, and I don’t have any desire to give it up.”

I like eating too. September was a bit exceptional, but as a normal course I think it’s a good idea to use Soylent for all of the boring meals - the ones where you just need to put food in the belly - and then truly enjoy all the other meals - the recreational meals. It’s interesting too that my enjoyment of them is inversely proportional to their frequency. A weekly turkey sandwich tastes way better than a daily one.

Soylent is Convenient

There are a number of scenarios that I ran across during my experiment that accentuated the convenience of my new found food.

  • Sometimes you don’t have time for breakfast. A Soylent is about as convenient as a bar.
  • Same thing when you’re heads-down at work and acquiring lunch feels like a real chore.
  • Reducing your diet to a very narrow menu of Soylent and water allows you to experiment with possible food allergies.
  • Lunch meetings at work afford ample opportunity to show off bad habits or spill food on your lap. Starting your own lunch at 11:00 and finishing at 11:01 frees you up to focus on colleagues, partners, or the topics at hand.
  • When you’re running around town running errands or having fun, stopping at a restaurant doesn’t have to be another thing on your list. Unless, that is, the rest of your family is on something other than a Soylent diet :)

Overall, it’s just nice to be in control of your own daily diet.

The Cost of Engineered Eating

Shelling out the money for a month’s worth of Soylents ($323 for 1600 kcal/day) feels like a lot. Consider, however, that this includes the convenience of the premixed option (a month of powder @1500 kcal/day is ~$180/mo), and may or may not be kinder on your budget than whatever else you were going to eat that month.

Some Other Things I Learned in Soylentember

Although weight loss was not my primary goal in this endeavor, I have lost 5 pounds over 4 weeks. That’s a healthy weight loss rate, and I always have the option to maintain my 1600 calorie diet or bump it up to 2000. Soylent is not a weight loss product - it’s just food, but it makes calorie counting much easier.

Air travel is not easy if you’re doing the liquid version of Soylent, because you can’t take liquid through security. I’m forced to check a bag and make sure that there’s not too much time between when I go through security and when I visit baggage claim on the other end, which is often more than 4 hours. If you like to get to the airport 2 hours early like me, then you are constrained to flights that are roughly 2 hours or less. This is a good reason to get some of the powder version (1.6), which is exactly what I intend to do.

The bottles are recyclable. I recommend giving them a quick rinse before finding your nearest recycling bin.

When I get my hands on some powder I intend to mix up a day at a time and then use some of my 2.0 bottles for mixing

I chilled my Soylent bottles in the fridge when I started, because I read that it’s better cold. It is good when it’s cold, but I later discovered that I like it at least as much when it’s room temperature. I think comes back to the texture. For some reason, when it’s cold it feels smoother in the mouth, but I like my Soylent to feel like food in my mouth. It’s more convenient leaving them at room temperature too, because you can just throw the day’s worth of food in your backpack and take off.

Soylent also offers bars that are 250 kcal and I’m told are quite delicious. I like having the option of finer control of caloric intake by adding in this smaller increment.

Going Forward

I’m not 100% certain about how I want to proceed now. Like I mentioned, I expected this to be a chore, and expected to be rather excited about getting back to normal eating when September was over. On the contrary, I quite enjoy my new freedom from food ceremony, and I’m sure I’ll continue supplementing some portion of my days kcal intake at least. I like how easy it is to come up with a daily plan of something like…

  • 2 Soylent 2.0 drinks (800 kcal) + 1 bar (250 kcal) + 1 light dinner
  • 3 Soylent 2.0 drinks (800 kcal) + 1 big dinner

I’m pretty sure I’ll either do one of those or perhaps just keep on with a fully Soylent diet! We’ll have to see.

OneDrive Sync Status

I don’t know how long the feature has been active, but I only recently realized that I can now see the status of all of the upload and download activity for OneDrive.

It used to be that you could hover over the OneDrive icon in the system tray and see some very basic status on OneDrive’s current effort to keep your local files in sync with your cloud storage. You saw that it was “Processing changes…” or that it had “247kB of 1.2GB uploaded”. It was slightly helpful knowing that it was actually working on something, but left a truck load of room for improvement.

Now if you hover over the OneDrive icon in the status tray, you get the upload progress as well as data transfer speeds, and if you click the icon you get something like this…

Now I can see that that MSDEVSHOW file that I recently dropped into my local folder is in fact on its way to the ether and nearing ready to share with others. Nice.

By the way, those 6 items it says I can’t sync are not a problem. I know why they can’t. It’s only because I haven’t opted to select some files for syncing yet.

I really should have provided feedback on this a long time ago, because I’ve been wanting it. Whenever you find yourself missing a feature or annoyed by some behavior in your operating system or software, make sure you find the right place to provide feedback and do it, because Microsoft (and likely other companies) really do look at what people want and steer their efforts that way.

In Windows, by the way, you can just hit Win + F and you’ll see your screen flash as Windows takes a screen shot of whatever you’re doing and then initiates a feedback request. That’s excellent.

npm Erroring Out on Windows 10 Fast Ring Build 14367

Just in case someone else is running into the same thing, I’m running Windows 10 Insiders Build 14367 (on the fast ring), and I’m unable to use npm. When I do a simple npm -v I get this error…

C:\code>npm -v
events.js:160
throw er; // Unhandled 'error' event
^
Error: This socket is closed
at WriteStream.Socket._writeGeneric (net.js:672:19)
at WriteStream.Socket._write (net.js:724:8)
at doWrite (_stream_writable.js:307:12)
at writeOrBuffer (_stream_writable.js:293:5)
at WriteStream.Writable.write (_stream_writable.js:220:11)
at WriteStream.Socket.write (net.js:650:40)
at WriteStream.stream.write (C:\Program Files\nodejs\node_modules\npm\node_modules\npmlog\node_modules\ansi\lib\newlines.js:36:21)
at Cursor.write (C:\Program Files\nodejs\node_modules\npm\node_modules\npmlog\node_modules\ansi\lib\ansi.js:157:23)
at Cursor.(anonymous function) [as show] (C:\Program Files\nodejs\node_modules\npm\node_modules\npmlog\node_modules\ansi\lib\ansi.js:226:26)
at Object.ProgressBar.hide (C:\Program Files\nodejs\node_modules\npm\node_modules\npmlog\node_modules\gauge\progress-bar.js:101:15)
3.9.5

My workaround is simply to type bash and get into Ubuntu where I have node and npm. There’s not really any disadvantage to this either since it operates on the same directory structure. I’m loving this Bash on Ubuntu on Windows thing.

Saving Your Code Settings and Snippets

I finally realized why I wasn’t investing a lot of thought or time on my Visual Studio Code snippet library. It’s transient.

I looked up where the user settings are being saved - C:\users\<me>\AppData\Roaming\Code\User.

Well, that’s a bit of a crock. It’s 2016. I want everything saved to my OneDrive folder so I can do a reload without considering the various settings files I’ll have to back up and restore. What, am I a caveman?

I searched VS Code and my registry and didn’t see an obvious (I only have about 2.5 minutes to spend on tasks like this) way to customize the path, so I did what any developer in this modern era would do. I posted a question on StackOverflow.

And in true SO form, I got an answer back very quickly. Well, it wasn’t exactly an answer, but close. DAXaholic responded that there is an extension for VS Code that may fit the bill.

It’s called Visual Studio Code Settings Sync by Shan Khan. You can install it in Visual Studio Code by going to your command palette (CTRL+P) and typing ext install code-settings-sync.

Now, I had to spend a few synapses on this strategy for saving settings. The way Shan set this up it saves your settings, snippets, launch, and keybindings to your GitHub account as gists. Creative, Shan. It’s not exactly the same as having my settings and snippets saved to my OneDrive, but I kinda like it. I do have to manually upload everything, and by manual I only mean that I have to execute the Sync: Update/Upload Settings command in Code. And then when I reload or slide over to a new work machine I have to Sync: Download Settings.

I sort of like, however, storing bits of code in my GitHub Gists repository.

One advantage is that I could easily share my settings with the world. By default, the extension creates the gist as secret. I don’t like secrets though, so I can just edit that gist on gist.github.com and hit the Make Public button.

And now I can share the link with you. Very cool. And that’s a live link too so that every time I add an awesome new snippet, you can see it. Now, I just have to remember not to put any secret keys in my settings or snippets :)

Anyway. I thought this was very cool. Kudos to Shan Khan on the cool extension.

Happy coding.

Index of my Raspberry Pi Posts

I’ve been doing a lot of hacking on the Raspberry Pi, and I’ve written a few articles on the topic. I’ve assembled all of my posts here for easy access.

  • Accidental Old Version of Node on the Raspberry Pi - I beat my head against a wall for a long time wondering why I wasn’t able to do basic GPIO on a Raspberry Pi using Node. Even after a fresh image and install, I was getting cryptic node error messages when I ran my basic blinky app.Lucky for me (and perhaps you) I got to the bottom of it and am going to document it here for posterity.
  • The Most Basic Way to Access GPIO on a Raspberry Pi - I’m always looking for the lowest level understanding, because I hate not knowing how things work. On a Raspberry Pi, I’m able to write a Node app that changes GPIO, but how does that work? Turns out it’s pretty interesting. I’ll show you.
  • Easy and Offline Connection to your Raspberry Pi - Getting a Raspberry Pi online is really easy if you have an HDMI monitor, keyboard, and mouse, but what about if you want to get connected to your Pi while you’re, say, flying on a plane?
  • Wifi on the Command Line on a Raspberry Pi - How to configure wireless connections on your Raspberry Pi from the command line.

Easy and Offline Connection to your Raspberry Pi

Getting a Raspberry Pi online is really easy if you have an HDMI monitor, keyboard, and mouse.

Subsequently getting an SSH connection to your pi is easy if you have a home router with internet access that you’re both (your PC and your pi) connected to.

But let’s say you’re on an airplane and you pull your Raspberry Pi out of its box and you want to get set up. We call that provisioning. How would you do that?

I’ll propose my method.

First, you need to plug your pi into your PC using an ethernet cable. If you’re a technologist of old like I am, you may be rummaging through your stash for a crossover cable at this point. It turns out that’s not necessary though. I was pretty interested to discover that modern networking hardware has auto-detection that is able to determine that you have a network adapter plugged directly into another network adapter and crosses it over for you. This means I only have to carry one ethernet cable in my go bag. Nice.

If you put a new OS image on your pi and boot it up, it already detects and supports the ethernet NIC, so it should get connected and get an IP automatically.

Here comes the seemingly difficult part. How do you determine what the IP address of your pi is if you don’t have a screen?

The great thing is that the pi will tell you if you know how to listen.

The means by which you listen is called mDNS. mDNS (Multicast DNS) resolves host names to IP addresses within small networks that do not have a local name server. You may also hear mDNS called zero configuration and Apple implemented it and felt compelled (as they tend to) to rename it - they call it Bonjour.

This service is included by default on the Raspberry Pi’s base build of Raspbian, and what it means is that out of the box, the pi is broadcasting its IP address.

To access it, however, you also need mDNS installed on your system. The easiest way I am aware of to do this is to download and install Apple’s Bonjour Print Services for Windows. I’m not certain, but I believe if you have a Mac this service is already there.

Once you have mDNS capability, you simply…

ping raspberrypi.local -4

The name raspberrypi is there because that’s the default hostname of a Raspberry Pi. I like to change the hostname of my devices so I can distinguish one from another, but out of the box, your pi will be called raspberrypi. The .local is there because that’s the way mDNS works. And finally, the -4 is an argument that specifically requests the IPv4 address.

If everything works as expected you’ll see something like…

Again, my pi has been renamed to cfpi1, but yours should be called raspberrypi if it’s new.

My system uses 192.168.1.X addresses for my wireless adapter and 169.254.X.X for my ethernet adapter.

So that’s the information I needed. I can now SSH to the device using…

ssh pi@169.254.187.84

I could just use ssh pi@raspberrypi.local to remote to it, but I’ve found that continuing to force this local name resolution comes with a little time cost, so it’s sometimes significantly faster to hit the IP address directly. I only use the mDNS to discover the IP and then I use the IP after that.

Provisioning a Raspberry Pi usually includes a number of system configuration steps too. You need to connect it to wireless, set the locale and keyboard language, and maybe turn on services like the camera. If you’re used to doing this through the Raspbian Configuration in XWindows, fear not. You can also do this from the command line using…

sudo raspi-configuration

Most everything you need is in there.

You may also be wanting to tell your pi about your wifi router so it’s able to connect to via wireless the next time you boot up. For that, check out my post at codefoster.com/pi-wifi. Actually, if you’re playing a lot with the Raspberry Pi, you might want to visit codefoster.com/pi and see all of the posts I’ve written on the device.

Happy hacking!

The Most Basic Way to Access GPIO on a Raspberry Pi

​I’ve been hacking on the Raspberry Pi of late and wanted to share out some of the more interesting learnings.

I think people that love technology love understanding how things work. When I was a kid I took apart the family phone because I was compelled to see what was inside that made it tick. My brother didn’t care. If it made phone calls, he was fine with it. I had to understand.

Likewise, I knew that I could use a Node library and change the GPIO pin levels on my Raspberry Pi, but I wanted to understand how that worked.

In case you’re not familiar, GPIO stands for General Purpose Input/Output and is the feature of modern IoT boards that allows us to controls things like lights and read data from sensors. It’s a bank of pins that you can raise high (usually to something like 3.3V) or low (0V) to cause some electronic behavior to occur.

On an Intel Edison (another awesome IoT board), the platform developers decided to provide a C library with mappings to Node and Python. On the default Edison image, they provided a global node module that a developer could include in his project to access pins. The module, by the way, is called libmraa.

On a Raspberry Pi, it works differently. Instead of a code library, a Pi running Raspbian uses the Linux file system.

When you’re sitting at the terminal of your pi (either hooked up to a monitor and keyboard or ssh’ed in), try…

cd /sys/class/gpio

You’ll be taken to the base of the file system that they chose to give us for accessing GPIO.

The first thing to note is that this area is restricted to the root user. Bummer? Not quite. There’s a way around it.

The system has a function called exporting and unexporting. Yes, I know that unexport is not a real word, but alas I’m not the one that made this stuff up, and besides, who said Linux commands had to make sense?

To access a pin, you have to first export that pin. To later disallow access to that pin, you unexport it.

I had a hard time finding good documentation on this, but then I stumbled upon this znix.com page that describes it quite well. By the way, this page references “the kernel documentation,” but when I hit that link here’s what I get…

Oh well.

Now keep in mind that to follow these instructions you have to be root. You cannot simply sudo these commands. There is an alternative called gpio-admin that I’ll talk about in a second. If you want to just become root to do it this way, you do…

su root

If you get an error when you do that, you may need to first set a password for root using sudo passwd.

To export then, you do this…

echo <pin number> > /sys/class/gpio/export

And the pin number is the pin name - not the header number. So pin GPIO4 is on pin 7 on an RP2, and to export this you use the number 4.

When you do that, a virtual directory is created inside of /sys/class/gpio called gpio4, and that directory contains virtual files such as direction, value, edge, and active_low. These files don’t act like normal files, by the way. When you change the text inside one of these files, it actually does something - like perhaps the voltage level on a GPIO pin changes. Likewise, if a hardware sensor causes the voltage level on a pin to change, the content of one of these virtual files is going to change. So this becomes the means by which we communicate in both directions with our GPIO pins.

The easiest way, then, to read the value of the /sys/class/gpio/gpio4/value file is…

cat /sys/class/gpio/gpio4/value

Easy.

To write to the same file, you have to first make sure that it’s an out pin. That is, you have to make sure the pin is configured as an output pin. To do that, you change the virtual directionfile. Like this…

echo out > /sys/class/gpio/gpio17/direction

That’s a fancy (and quick) way to edit the contents of the file to have a new value of “out”. You could just use vior nanoto edit the file, but using echo and the direction operator (>) is quicker.

Once you have configured your pin as an output, you can change the value using…

echo 0 > /sys/class/gpio/gpio4/value //set the pin low (0V)
echo 1 > /sys/class/gpio/gpio4/value //set the pin high (3.3V)

Now that I’ve described the setting of the direction and the value, you should know that there’s a shortcut for doing both of those in one motion…

echo high > /sys/class/gpio/gpio4/direction

There’s more you can do including edge control and logic inversion, but I’m going to keep this post simple and let you read about that on the znix.com page.

Now, although it’s fun and satisfying to understand how this is implemented, and it might be fun to manipulate the pins using this method, you’ll most likely want to use a language library to control your pins in your app. Just know that the Python and Node libraries that change value are actually just wrappers around these file system calls.

For instance, let’s take a look at the pi-gpio.js file in the pi-gpio module…

write: function(pinNumber, value, callback) {
pinNumber = sanitizePinNumber(pinNumber);
value = !!value ? "1" : "0";
fs.writeFile(sysFsPath + "/gpio" + pinMapping[pinNumber] + "/value", value, "utf8", callback);
}

When you call the write() method in this library, it’s just calling the file system.

So there you have it. I hope you feel a little smarter.