Excessive Portability and Embedded Development

Which is better?


/* Read the angle register (ANGLECOM) */
angle = spi_write(0xFFFF);

or

/* Read the angle register */
angle = spi_write(A_READ | A_PARITY_1 | A_ANGLECOMREG);

Now, you don't have to understand exactly what's going on here (and the actual process of reading an angle from the AS5147 rotary position sensor is a little bit more complicated), but I am trying to make a point.

I would argue that the second code snippet is a waste of time. (Some presumptions here: You had to define A_READ, A_PARITY_1 and A_ANGLECOMREG).

But, why would I advocate the hard coded version?

1. The chip (AS5147) isn't going to change SPI command structure anytime during its production cycle.
2. If you choose a new chip, you are going to have to study it and figure out the hard coded values anyway.
3. The abstraction in the 2nd code snippet is going to only work for this exact chip.
4. You have to work out the bit twiddling anyway (to come up with A_READBIT, etc)
5. 0xFFFF is what you will see in your debugger
6. It is *always* 0xFFFF 
7. Ease of modification doesn't work here. If you go "oh, that should be A_PARITY_0" and change it (without verifying the actual resulting write value, it is going to cause a lot of debugging woes).

This is sort of an argument between "ease of writing" vs "ease of debugging" and in embedded development, "ease of debugging" is what you are really shooting for (or maybe call it "ease of validation").

I see the same thing happening with STM32's HAL or StdPeriph.  There is a focus on making it easier to load up registers (often taking 1 line of register loading code and stretching it into multiple lines of structure loading using verbose enums/types you have to look up).

To be honest, when I work in Forth on the STM32, I don't have such luxuries and my program is full of well documented hex and binary register banging.

Attack At Dawn

This is a painting on display at The Walters Museum in Baltimore Maryland. (http://art.thewalters.org/detail/4911/the-attack-at-dawn/).   It is by "Attack At Dawn" by Alphonse de Neuville.  

I am not particularly a fan of military battle scenes, but there is something about this painting that I can't get the image out of my head. 
This photo does it no justice.  The somber, winter setting, the lighting, the mastery of painting techniques. It is not a famous painting, but it does so many things that resonate with me: The distant foggy morning sky, the snow, the dim light sources (e.g. dawn, the lamp post, the doorway on the left, the rifle fire), the sparse brush strokes, the sense of desolation.
Go see it, if you can.

Literate Programming... A Revisit

For someone reason (nostalgia?) I've been re-visiting Donald Knuth's concept of Literate Programming.

(For a quick intro, critique and discussion on this approach see this blog entry and the responses.)

I first discovered Literate Programming via looking at TeX sources in the 1980s.  Then I became somewhat obsessed with the approach around 1992 with the publication of Literate Programming by Knuth. This is still one of my favorite books on programming.

I still like to thumb through TeX: The Program (likely the largest Literate Program ever written).

Perhaps I am starting to revisit Literate Programming because of my full-time-deep-dive into embedded programming (again).  Still stuck with C and code that is supposed to work (I deal more with "firmware" than software these days -- code that can't just be frequently updated, is hard to unit test and must be very, very reliable).

Literate Programming doesn't fit well in today's rapid development, big team, fastest-time-to-market culture.  But, when I am writing control systems with little instructional software/literature available (e.g. learning how to spin a BLDC motor using sinusoidal waves), I start thinking about approaching it in a literate style.

Shhh... don't tell my partners, but I am definitely thinking about using cweb  or perhaps cwebx for this ;)

SPLAT Logic Analyzer

Found: A Logic Analyzer written in Tachyon Forth on a Parallax Propeller chip.
This is insane.  I love it.

https://docs.google.com/document/d/1vszFLwzIfwMEqe2vWA0y4HwVIc4uVpxyjmApKNlY8QQ/pub

Somewhere, in a box, at my last job, is an "over the air" (GSM/SMS) remote control device that I developed using the Propeller chip and Tachyon Forth.  It was a prototype I  put together in less than 2 months and "field tested".  It was an interesting (and fun) experience. I would have love to have used this logic analyzer during development.

Spinning a motor is hard

I'm trying to spin a 3 phase motor really, really slow.   For this I have chosen Sinusoidal Commutation.  Just a few sine calculations and I'm good, right?

Ugh.

Sinusoidal commutation of BLDC motors is hard.  Even so-called "open loop" commutation (which still expects feedback -- is it still really "open"?) is difficult.

You can find a google load of papers on how to perform (6 step) trapezoidal commutation and then some that kind of talk about sinusoidal.

It's all maddening and the reason why motors are its own field of study.  Lots of physics. Lots of math. Lots of stuff you can't shortcut.  Jerk, torque ripple, back EMF.  Don't get me started on rotors and pole count.  How about Phase finding?  Know how to do that?

To spin, you must have feedback!  Don't Hall effect sensors? How about with angular magnetic encoders? If you are man (or woman) enough, you venture into FOC.

I'm spending weekends and some weeknights learning how to spin a motor so me and my partners can build a killer robotic application. (Killer may be a bad choice of words....)

I'm really learning how much I don't really know.

Spinning a motor is hard...

Taking a SIP from the VoIP fountain....

Bad metaphorical post title aside (ouch),  I am currently investigating "cutting the Vonage cord" (another bad metaphorical allusion).

I haven't had a proper land line in 10 or so years. Vonage has served me well.  But, I find that with everyone in my family owning a smartphone, we rarely use our home phone line.  As anyone who has called us will know, sometimes we can't find our "wireless" phone(s) -- is it buried in the couch cushions again?  We are also horrible about retrieving voice mail (even though we have Vonage forward transcripts to our smartphones).

Really, outside of having a number "for our house", we don't use it much.  But our monthly bill for this convenience is over $30 per month!  I know, I know... why don't we just find a lower cost VoIP provider?  But that still requires us having to swim in someone else's pool (sorry about that, there I go again).

But, hey... wait a minute!  I am a software engineer who specializes in communication.  There must be something I can do here.  All I need is some way of getting my home phone number to forward to a PBX under my own control.  Think of the things I could do!

I could...

• Have the call ring to any smartphone that is registered on my Wi-Fi (i.e. mine and my wife's phones when we are home)
• Forward the call to voice mail immediately if we aren't home.
• Register another "business" phone number that does something similar... basically track me down (e.g. smartphone or home number or voicemail)

..and so much more!

So, I start looking at FreeSWITCH and Asterisk.  Wow!  I need a book, or two, and a lot of time.

(Another variation of swimming in someone else's pool).

Okay, so do I really need a full blown PBX to do this?  Nope. I can do most of this with a cheap DID (Direct Inward Dialing) provider that could forward to a SIP proxy (of my own configuration or design).  (I won't go into details about SIP here... just know that it is the standard Internet way of locating and setting up calls. It is pretty complex too, but it is fundamentally a protocol specification.)

So, I start looking at OpenSIPS and over SIP server solutions.  It looks like all the pieces are there to do what I need. I just need to write a script....

Okay. My engineer senses start pulsing again (sort of like Spiderman's senses but rather than danger it warns me that I am about to use a complex system to do what seems so simple in my head).  I don't want to solve my problem with a simple OpenSIPS configuration... I want to intimately understand what is going on inside of SIP and implement just enough to do what I want.  How better to learn a system than to dive right in and try to build one yourself?

By learning OpenSIPS, I'll become an OpenSIPS expert but I won't really know how SIP works.   Sure, they take care of the plumbing, but I am interested in the plumbing.

So, I start with the SIP RFC .  Well that's over 200 pages!  Okay, Todd.. slow down. What do I minimally need to let two VoIP user agents (i.e. phones or smartphone apps) talk to each other?

I start from there.... and here I am today.  I've got some primordial code handling SIP registrations over UDP.  I have a long way to go, but I am going to have fun with it and I am going to learn a lot. 

Maybe I'll finish enough of it to put it out there as open source. Not an OpenSIP competitor, but a super simple, super hacky way of creating your own lightweight home VoIP system.

Note: Currently using LuaJIT and Copas socket server to play around with SIP and I as I mentioned above, I've got Registration working.  Ooooh... so much fun!

Hackable (Software) Things

I like hackable things. I'll keep that vague, because I am in a vague mood.
See if you can spot the common theme:

1. Emacs
2. TeX / LaTeX
3. Forth (interactive on an MCU)
4. Snabb Switch
5. Smalltalk  (Squeak)
6. Unix command line (awk, sed, kornshell, bourne shell, maybe bash, etc)

Okay... why?

They are worlds at my fingertips.

They don't use XML.

They are extensible.

I can make them do useful things.

With the exception of #3 (Forth), none really manipulate the "physical world".

Speaking of Forth... having shipped a few professional devices built with Forth, I still haven't found anything nearly as useful or fun for MCU work.

Something I would love to have for embedded MCU work:

A nice REPL / Editor environment (host side, please) for manipulating/deploying eLua on MCUs. 

eLua has poor interactivity support, but I wonder if remotely instrumenting it is a better approach... maybe via ZeroBrane or Emacs?

Premature Optimization during Design

As I design my embedded software, I am always looking for the most efficient tools and design. We have limited resources and must therefore constrain our designs.  Or do we?

I remember struggling to get Donald Knuth's TeX typesetting system to compile and run on the big DEC2060 timesharing system back in 1984. It was a beast of an application and not written to run on anemic platforms. It was Knuth's idea to solve the typesetting problem, not write an application that would run on limited hardware.

Now, TeX (same sources pretty much) can run on your Android phone.

Back in 1986 I was trying to get Richard Stallman's Emacs to compile and run under Unix. It was a big, bloated and slow beast  (but worth it for all the power it gave me -- I was already an Emacs addict for a couple of years).

Now, I install it on every Linux/BSD laptop I use and fire it up as needed.

These systems (and others) were not designed to work on minimal hardware, but over the years hardware caught up with them.

I am not advocating that IoT devices use big bloated tools, but as far as "basestations" go... why are we constraining ourselves to RasPis and Beaglebones?

Mutter... Adventures in VOIP/messaging systems

Over the past couple of years I've been playing around with a "toy" Mumble server I developed.
Mumble, if you don't know, is a popular gamer VOIP and messaging system.  It is open sourced and has clients running on Windows, Linux, iOS (iPhone) and Android (I prefer Plumble).   It has a published spec for communication so it is relatively easy to build a minimal server.  I've built one in the past in Erlang and have recently started one in Lua(JIT).

Why would I want to implement my own Mumble server (I'm calling it Mutter) when a perfectly good one exists as part of the Mumble project?  Well, I am curious how many interesting things I can do with a compliant server without touching the client software.

Some of my experiments involve creating additional levels of authentication (e.g. a query response from a server bot, additional detection of client OS/hardware stuff, etc) as well as the potential to bridge to other VOIP or messaging systems.

Other things I am curious about playing with is "adhoc" conference calls that could spawn quickly and privately in the cloud. 

Right now it is mostly for fun. I've got basic messaging and TCP voice channels working. I am not interested in building a full blown Mumble server (that already exists!) but curious as to what can be done minimally....

S.A.F.E: An IoT compatible Manifesto

My home monitoring projects/products follow a manifesto I call SAFE.  SAFE is an acronym for Set And Forget Engineered.  It follows the basic tenant that home monitoring systems should be reliable and not require lots of care and attention.  You set it and then forget it.

This manifesto doesn't exclude IoT (Internet of Things) devices, but it has some rules. Let's consider the class of devices to include: Flood monitors, Stove usage monitors, Motion detectors and Entry/Exit monitors.

1. If you don't run off of AC, your nominal battery life should be 5 years.  Assume 2 years of worst case (power consumption-wise) performance.   Do you check/change your smoke alarm batteries religiously every year?  Maybe not.  If you can't guarantee 2 years of performance (and you are a critical monitor) then you should run off of house current (AC).
2. If you need to run when power is loss, then you should have backup batteries that last at least a couple of days. This is particularly important for Flood monitors, etc.
3. If you can't automatically recover from a power failure, use backup batteries to keep the system running or use persistent memory to snapshot states.
4. Your device should have some "local" alert capability and not rely 100% on the Internet for notification.  If I am in the house, there should be an audible alarm and not reliance on my smart phone being notified via the Internet.
5. If Internet notification is critical, don't trust Wi-Fi.  Let's use an analogy:  Your car's critical systems (engines, steering, braking, locks, etc) should, by design, run on a separate network than your Entertainment system (radio, etc).  Your IoT device probably should follow that same rule. Wi-Fi can get congested, it can have password changes, it is a common target for attack.  But what can you use instead of Wi-Fi? Consider ZigBee, XBee or other more robust protocol (no, not Bluetooth!) as the delivery transport to the home router. All home routers still feature Ethernet ports so your transport receiver can be plugged in there. You still rely on the monitor but you are not affected by all the issues with Wi-Fi.  Now, of course, you should consider encryption and authentication too when using a non-Wi-Fi protocol...
6. Don't design for over the air software/firmware updates. This is a HUGE security hole and although you may have thoroughly thought it through -- you haven't.  Get your software as  correct as possible and consider doing updates through a computer or smartphone "directly" and "physically".  Things that can be controlled through the Internet will be a nice fat target for people who want to control your stuff through the Internet.  Don't advertise your house as hackable!
7. No SD cards. Nope. SD cards are not designed for reliability or longevity. Use persistent memory that has at least a 10 year retention.
8. No rechargeable batteries.  How long do you really get on a L-ion/poly?  Two years? Five years?
9. Avoid LCD/button interfaces as much as possible. What is this, the 1990s?  If you need a way to silence an alarm or (temporarily) disable a sensor use touch or tap and a simple indicator. 
10. No disabling or critical manipulation through the Internet.  Sorry, see #6.
11. Know thy hardware. Don't just choose a Raspberry Pi or Arduino unless you know exactly how each critical component is rated (e.g. environmentals, write duration, etc).
12. Know thy software. Don't just load up a Linux and go. Are there processes running you don't understand? Update software maybe? 

I try and to design to these tenets. I am surprised how many commercial IoT devices seem to ignore them. 

Elderly Monitoring: Revisiting with Brutal Simplicity

Short backstory:

I've been running over a year now with the current Elderly Monitor system in my house. Mother-in-law has dementia and the current system lets us know her general movements throughout her living space (e.g. how long has she been up this morning? How many trips to the bathroom?)  and whether or not she has opened the front door (e.g. is she going for a walk? Has she made her escape?).
The current system consists of X10 wireless monitors for the door (open/close) and living spaces (motion detection).  This is fed to a small Linux computer I've coded with tracking logic, the ability to speak "Front Door is Open", and the ability to communicate (event message and status query) using XMPP to a cloud server (Digital Ocean) and to our smart phones (running Xabber XMPP clients).
It has been a success but with the lessons learned  I've found the most critical aspect of this setup is the ability to simply detect that the front door has opened and then notify us via a speaker in our bedroom.  All of this flows from X10 to Linux computer to soundcard (the Cloud is not involved here).  Still, this seems overly complex. Can it be simplified yet still be expanded to deal with "enhancements" in the future?

Let's review some of the short comings of the current solution:

1. X10 Wireless - This has been "mostly" reliable and inexpensive. Still, I do have an RF noisy house and what if the neighbor starts using X10 RF?  (Not likely, but for a rock solid solution, this is a weakness).  Also X10 pretty much means that I have to have a full blown PC (with X10 CM19a transceiver) unless I decide to seriously hack the protocol and build my own RF receiver.
2. The PC - Why do I need a full blown PC just to do the basic "Door is Open"?  
3. The Cloud - Sure, I've got it, but if I want to distribute the "Door is Open" beyond the bedroom speakers, I have to connect via the Cloud (currently) and subscribe to XMPP messages (essentially what I do with the smartphone).  I need to make some of this stuff local.
4. Batteries. Batteries. Batteries - Damn. Did the X10 sensor batteries die? When did I change them last? Ugh.
5. There is no indication of whether or not she has just opened the door or left the house. I can code this logic, but since I want to address the above short comings first, this will have to wait.

What is the simplest thing I can possibly do?  Especially if I want to add logic like #5?

I am revisiting this problem and addressing it with brutal simplicity. 

Two things are going to get ripped out:

1. The PC. No more computer. A microcontroller should be able to do this.
2. No more X10. I'm going "wired". No more batteries either. I want to "set and forget" this thing. I'll deal with a little wiring. All of the current sensors are less than 20 feet apart: Door, hallway, bedroom, bathroom.

Stay tuned.  More details to follow as I hash out my brutal "simplest thing that could possibly work" design.

Elderly Monitoring: Telling a Story with minimal sensors

How many sensors do you need to tell a story?

I have a motion sensor in my mother-in-law's room, her bathroom (down the hall from her bedroom)  and an open/close sensor on the house front door (which is next to her room).   With just these two (cheap) X10-RF sensors I can tell a lot about the nightly activity of my dementia suffering guest.

If you  haven't been following this blog's "elder care" stories: My mother-in-law has dementia so she lives with me and my family. She is apt to get confused and wander. Her room (the only available extra room in the house) is unfortunately next to the front door.  The rest of the bedrooms are one floor up. Mother-in-law needs constant monitoring. She has "escaped" our house several times (at night and at dawn -- when we are still asleep) with the idea that she is going to walk to "her house".  She also complains of insomnia and chronic pain.  Is she sleeping at night? Is she up wandering the house?

So, I've designed a cheap  sensor-based monitoring system. I explained that tech setup elsewhere.  Here I want to posit the question: What kind of "story" can you tell with a couple of sensors?

With just a bedroom, bathroom motion sensor and a sensor to alert us when she opens the front door, I can talk about the following:

• Did she leave the house or is she just "checking the weather" (door opens but is followed by movement in her bedroom)?
• Is she restless at night (motion in bedroom)?
• How many times did she visit the bathroom?
• Is she in the bathroom for an unusually long time? (Bathrooms are where a high incident of heart attacks tend to occur)
• When did she get up in the morning? (Motion in bedroom, then bathroom, then bedroom again)

Now, my current software doesn't tell a complete story (yet), but with the reports/alerts it generates, my wife and I can determine with a quick view of the data on our smartphone, any of the above scenarios.

I'd like to add a couple more sensors, maybe a light sensor and temperature monitor for the bedroom to help flesh these stories out.

The moral (of this post) is: You can tell a lot with just a few sensors and a lot of common sense.  It isn't about the "hardware tech". It is, ultimately, about making sense of data.  I want to get my software to the point where it "tells the story" rather than just provide data for my wife and I to review.  Here is my ideal morning report (sent to my phone instead of the raw data events):

Betty slept between 9:30pm and 6:15am, awaking at 11:15pm and 2:30am to go to the bathroom.  At 6:30am she opened the front door, closed it and went back into her room. Her room light has been on since 6:45am and there is currently no movement in her room.

I don't need this report in verbose english (like above), but I should be able to quickly derive the above story from summarized data points.  All of this can be surmised by the current three sensors.

Hacking Inside Out vs Outside In: Lua vs Clojure

I've got a couple of CFT (Copious Free Time) projects going on at the same time:

• My re-architecting/re-writing of my Eldercare home monitoring system (currently in C++11)
• My  Adhoc private VOIP/chat for conferencing project.

I've so far have 2 semi-working (new) implementations for each of these projects.  I  started developing both in a high level programming language (Clojure) and ended up runnng into a few walls that caused me to look at alternative implementation languages (in both cases Lua(JIT)).

With Clojure I got to swing around futures, core.async and rich data structure manipulation, but I hit implementation walls involving libraries (mostly Java) that don't quite do what I want. Soon I was finding myself installing broken, old or incompatible packages.   

Abandoning Clojure, I headed back to LuaJIT. Here I had much more control over my environment, but greatly missed builtin things like futures,  core.async and rich data structure manipulation.

Clojure and LuaJIT represents the opposite ends of the spectrum but they do have the ability to overlap (I can drop down to Java/JNI in Clojure and I can evolve Lisp-like richness out of Lua).

It's bottom up vs top down, or inside out vs outside in.

I need to bite the bullet, pick a direction and stick to it.

Confab - Adhoc private VOIP/chat for conferencing

In my copious free time I am working on a new system I am (tentatively) calling Confab.
Confab is an adhoc (on demand) VOIP conference call system utilizing the popular gamer VOIP/chat system Mumble.

Confab will use any Mumble client (iOS, Android, Windows, Linux, etc) but will only implement enough of a subset of a Mumble server to allow for quick conference calls. (Mumble certs won't be used for authentication, so you won't have to install certs on your Mumble client.)

The idea is that there is no conference call service running until you need one. And, once you are done, it goes away.

But, why not use free stuff like Skype or Google Hangouts?

1. Skype and Google Hangouts require registered accounts (with personal info about you)
2. Skype and Google Hangouts persist your previous chats (which can be annoying if you never want to talk to these people again)
3. Your account is "permanent". Your connections, your password, etc. Always there waiting to be cracked or exploited.

With Confab, you point your browser to the Confab Website, enter a conference start time and you are provided with a server name, a port number and a small once use password (e.g. a23gHYz). The Confab Mumble server (tied to the designated port) doesn't accept connections until the startup time.
Because each session is tied to a unique port number, there is more security than can be offered by a single server with "channels" or "rooms".

You give your participants the server name, the port number and password so they can join.  Once people join you can chat(text) or talk(voip).  The Confab session terminates after 10 minutes of idleness (no one is talking or chatting).  You can also configure an absolute call duration time (e.g. 60, 90 minutes, etc).  Each Confab session should support a couple of dozen participants.

Why not just use a normal Mumble server?  I want to drop the gaming oriented features, but I plan to add unique server-side features such as:

• Federated servers - connect multiple servers to allow inter-conference calls.
• Support for bridging to other "open" chat/voip servers.
• Support "audio casts" (recording and simultaneous broadcasting of audio via one user's phone/computer) to dozens of participants
• Moderated conferences (e.g. question and answer sessions, etc) via helper bots.
• Voicemail (and text message) capabilities (call in and leave a message for others)
• Possible support of POTS (plain old telephone service) bridges

I'm finishing up the basic Mumble-compatible server right now (not yet supporting the above features).  It is designed to be lightweight and fairly scale-able. I have no intention on providing or modifying existing client side software.

My server software will be released as open source.  I am planning on setting up a small test server on Amazon AWS or Digital Ocean.  I'll let you know (here) when it is stood up.  If this works out, maybe I can get some donations (Amazon, PayPal, etc) to offset the costs...

Elder Home Care in an RF noisy house

The BT tags I mentioned in my previous post is acting erratically.  During certain times the tracker tokens lose contact with the server (for minutes) even if just a couple of feet away.  BT LE is supposed to be broadcasting on a channel not used by IEEE 802.11 Wi-Fi, so I am not sure what is drowning the broadcast. I don't have a 2.4Ghz wireless (house) phone so that isn't the culprit.

I don't have a spectrum analyzer, so I am limited in my investigative resources...

I'd hate to have to drop down to 433Mhz sensors.

The good news is that this can possibly be solved in software.  The problem is the "false positives".  Since the monitor notifies me upon the sensor going out of range, when these RF anomalies occur I am falsely alerted.  One approach is to have a "control" tag permanently installed in the room with the detector. If both the control and tracking tag go "out of range" then it must be an RF anomaly and I shouldn't be notified.

Phase II of Elder Home Care (formerly Elder Home Alone) Monitoring System

It's been a while since I've posted about my home monitoring system.

Short recap:

A couple of years ago, my Mother-in-law lived alone in a Condo and was prone to leave her stove on accidentally and other forgetful things. I started working on a home care monitor for the "Independent Elderly".  It would include basic occupancy trackers, water overflow detectors and stove/kitchen monitoring (to make sure it isn't left unattended and to monitor her eating habits).

Well, fast forward to..  my dementia diagnosed Mother-in-law moved in just over a year ago.  So, the problems are a bit different.  She wanders. She gets up in the middle of the night to go to the bathroom and can't find her way back to her bedroom. She may go upstairs in the dark and stumble or venture outside.  Sometimes, during the day she may decide to walk home... to her childhood home, several states away.  She is old, but fast.

The current system uses "cheap" X10 RF motion detectors and door monitors. I can review past activities (e.g. when did she get up this morning? Did she frequent the bathroom last night?) or I can be alerted to the house door being opened (Is she just checking the weather? Is she going to sit on the porch? Is she going to make a run for it?).
The alerting system consists of some software I wrote (runs under Linux on a small Intel NUC PC) and it, currently, sends XMPP (Jabber/Chat) messages to a cloud server (on Digital Ocean) which runs Prosody XMPP server. My wife and I are connected to this server using XMPP chat software (Xabber) on our Android phones.  We can query the monitoring system from our phone or be chimed when the door opens.

It has run well for a year now. :)

But, now that my Mother-in-law is prone to taking long unannounced walks, this system is not enough.
The phone chimes when the door is opened. Is it one of the kids? Is it her checking the weather? Is the door already opened from a previous check?  Is she *really* still sitting on the porch 10 minutes from now?

So, after an early phone call one morning, from the Police (she managed to get several blocks from the house before sunrise), we decided we needed to invest in a tracking solution.

Most tracking solutions either involve GPS (battery drain, and overkill -- if we know that she has left we can pretty much find her in a matter of minutes -- if we know she has left.

Not a lot of solutions out there.  Found one on an Alzheimers website. It *only* requires recharging every 48 hours. Ugh.  What do we do while it charges? Do we need to buy two?

So, I decided to look into BT LE (Bluetooth LE). I had built several BT LE tags years ago and was interested to see what the state of the art was today.  Apparently, Fitbit uses BT LE beaconing. That is, every second or so it broadcasts it's address so your phone can handily connect to it on demand.
BTE has a very limited range, but that's okay.
Also, Apple has been pushing "iBeacon" for their own (non-elderly) tracking purposes. They have a spec and a number of hardware vendors. I found this tag on Amazon for $14. Although meant to be used with Apple devices, it does a simple BTE beacon/broadcast that I can readily track.  This is perfect size to be "hidden" in her purse (in a small crevice/pocket) and the battery should last 6 months - 1 year (I'll assume 3 months and schedule an early battery replacement).

Armed with the BT 4.0 PCI card in my NUC, I attacked this challenge a week ago. Now I have a rudimentary system that will let me know when my Mother-in-law has ventured beyond the front porch. My android phone (running Xabber) is notified whenever the tag goes out of range.

There is a lot of work to perfect this, but I am happy with the preliminary results. I will be moving the notifier beyond the phone (maybe home media -- DNLA/TV/etc or just speakers on the NUC) and making it work locally in case we lose Internet connectivity.

I will be releasing the software into open source within the next few weeks.

Virtualization: Your PC is a Universe

PCs (and, honestly I am really talking about Laptops and the newer PC replacement tablets) are so powerful that they no longer have to be thought of as singular "client" resources.  That is, with sufficient memory (let's start at 8GB RAM)  and with enough SSD speed storage (>128GB),  folk like myself typically run many virtual computers inside our computers.

If I need to run Windows, I just fire up Virtualbox. If I need to do server development, I can pick stuff like Vagrant, Docker or go directly to LXC.  I can do Android development. I can do Windows development. I can try out Haiku or some new BSD.  I can do all of this without changing the underlying OS.  The underlying OS, in fact, is starting to become irrelevant.  Give me a Windows box and I can do full Linux stuff on it without replacing the OS: Just start up a Linux VM.

The thing is, at any given moment, my laptop is a Universe of virtual computers. I can network these computers together; I can simulate resources; I can test them, probe them and manipulate them.

This is new. Yes, yes -- the tech is pretty old (e.g. virtual machines), but the realization of this tech on a portable computer is new.

If you want to see where we may be heading, check out something like Rump kernels or OSv. We are starting to leave the OS behind and look at computing in terms of "microservices" -- collaborating virtual computers that solve a particular problem.

With the resources we now have on hand, why are we talking about systemd and Dbus and other single computer entities?

The next time you approach a design, try thinking about how your laptop can be *everything*. And then let that influence your design.

I will be Cyborg.

I haven't had a lot of time to post to this blog and I am wondering if this is the end of the line for it.
Well, we will see.  But for now...

I am approaching 50 (in 1.5 years) and my eyes are shot (I'm very near sighted).  The screen is blurry (I have transitional bi-focals, so my "clear" view is pretty marginal) and isn't going to get any better.

So, if my eyes sight starts to quickly wane (my eye doctor isn't really concerned... yet), what do I do?
While I can use magnifying glasses for my circuit work (which starting to become a thing of the past for me anyway), what about my programming and computer science stuff  (i.e. my screen work)?

Duh.
I'm a programmer and technologist.  I can hack something together to supplement my poor vision.  Even if I were to go blind (that isn't currently in the cards, but who knows), there are ways to continue to do "Computer Science".
There is technology already out there, and I can always invent what I need to aid me if my eyesight worsens.

Sometimes I forget that, with software and some gadgetry, we invent whatever we need. We are indeed sorcerers and alchemists :)

Forth and the Minimalist

Not all Forth programmers are minimalists, but chances are, if you use arrayForth, colorForth or something inspired by it (like MyForth), then you may be a minimalist.

Being a minimalist, you seek the simplest, most concise use of resources.  You tend to avoid rambling code and the idea of calling a (3rd party) library function makes you uncomfortable.

One of the reasons I like using MyForth (and the 8051) is that it forces you to think about how to simplify the problem you are trying to solve.  This is a good exercise but also offers some advantages when you are working on low power (or very tiny) embedded systems.  No matter how beefy an MCU can get, there is always a need for something "smaller" and lower power (e.g. a tiny low transistor count 8 bit MCU has more chance running off of "air" than a 32 bit fast, feature rich MCU).

The 8051 has rather poor math capabilities. Everything is geared toward 8 bits. If you use a C compiler, this is hidden from you.  The compiler will generate a ton of code to make sure that your 16 or 32 bit math works. This causes code bloat and will slow you down -- thereby causing more power consumption.  Programming in a minimalist Forth makes you think about whether or not you actually need the math.  Is  there a cheat?  You look at old school methods and you may find them. I grew up on the 6502 (Commodore VIC20/C64, Atari, Apple, etc).  You did all you could to avoid doing "real" math (especially if it broke the 8 bit barrier).  You had limited resources and you made the most of what you had.

But, is this just an "exercise"?  I don't think so. There are practical benefits that go beyond just old school cleverness. You (can) have more compact code that performs better. The less code you produce, the fewer chances for bugs. The less code you produce, the more reliable your product.

Gone are the days (for most of us) of penny counting the costs of components. I'd rather have a bunch of simple components (e.g. logic gates, simple MCU, peripheral processors etc) that do work for me rather than a big processor with a complex library.  Chip components tend to be "coded" at a higher level of quality assurance than pure libraries.  I trust a USB->serial chip more than some USB->serial library for my MCU. If the library fails, they say "update". If a chip fails... they risk going out of business -- who trusts production runs to faulty chips?

In the end, the minimalist is fighting the status quo.  It is a futile fight, but we can't seem to give it up. It is in our nature.

AFT - an elegant weapon for a more civilized age..

This is a sort of nostalgic post and, in some sense, it is also a "toot your own horn" one as well.  I am writing this mainly for myself.  I am trying to remind myself what I've liked most about programming.

Years ago, actually almost 2 decades ago -- around 1996,  I wrote a text mark up system called AFT.  AFT stood for Almost Free Text. It was inspired by Ward Cunningham's original Wiki mark up but went further.

I had a problem. I didn't like using WYSIWYG word processors and the world was moving towards HTML.  I liked Ward's mark up. He was using it on this new "Wiki Wiki" thing. I answered an invite sent to the Patterns List and became one of the first of the wiki users in 1995.  (But that is a different story or a different time.)

AFT was my attempt at a writing system to produce publishable (web and print) documentation.  Since then, it has developed a (now waning) user base.  You can see how many web pages/documents use it without changing the default "watermark" with this query.

As of Ubuntu 14.04, you can get AFT by issuing an "apt-get install aft" against the standard repository.
I think it is still part of FreeBSD "world".  I believe it still runs under Windows too.

Various "modern" mark up languages (written in "modern" programming languages) have since surpassed AFT in adoption, but for me, it still is a more elegant and pleasurable experience.

Over the years (although not very recently), I've updated, fixed and generally maintained the code.  There are no known crashes (it literally take whatever you throw at it and tries to produce good looking output -- although that may fail) and it doesn't require me to look at the HTML (or PDF) manual  (written in AFT!) unless I want to do something complex.

AFT is implemented in Perl. Originally it was written in awk, but I taught myself Perl so as to re-implement it in the late 1990s.

It is, for me, interesting Perl code.  I have modernized it over the years, but it still doesn't depend on CPAN (a good thing if you just want to have non-programmers "download it" and run without dependencies -- yes I know there are packaging solutions to that problem today...).

AFT has "back end" support for HTML, LaTeX, lout and some rudimentary RTF.  These days I think mostly HTML and LaTeX is used.

You can customize the HTML or LaTeX to support different styles by modifying or creating a configuration file.  This configuration file is "compiled" into a Perl module and becomes part of the run time script.

AFT has been a pleasure to hack on now and then. It still runs flawlessly on new Perl releases and has proven not too fragile to add experimental features to. I've accepted some small code fixes and fragments over the years, but generally it is mostly my code.

As I wrote (and rewrote) AFT, I thought frequently of Don Knuth's coding approach (as excellently documenting in my all time favorite book on programming: Literate Programming).  I certainly can't match the master, but the slow thoughtful development he enthuses was inspiring.

Over the years I've gotten a few "thank you" notes for AFT (but nothing in the past few years) and that makes it my (to date) proudest contribution to Free Software.

Maybe I'll dust off the code and introduce some more experimental features...