Sunday, December 05, 2010

Important techniques for (future) multi-core embedded development

These three approaches intrigue me:  Staapl, Lava and MyForth. They don't address "multi-core embedded processors ", but I think their "meta system" approach will be integral in making it easier to developer for embedded multi-core controllers.

Tuesday, November 23, 2010

The Lonely Programmer (Hacker)

I've been noticing books on the market (and some blogs too) that speak of our newly emerging "Maker" culture -- a culture where people fed up with intangible abstract work (do you sit in a cubicle pushing numbers?) are turning to the gratification of hands on creation. They say that working on physical things can give you a deep sense of accomplishment that nurtures our primordial tool building minds.

I put forth that some programmers can get this feeling from the intangible and abstract.  I grew up working with my hands (art, electronics, and just generally building stuff).  Programming became an extension of that. It my mind, my code held the same sense of accomplishment and gratification as building something with my hands.  I became enamored with virtual worlds!

Nowadays, however, I find that a lot off programmers spend significant time worrying about languages, syntax, test coverage and code re-use. These are topics of varying importance, but they are just about honing your skills.  At some point you have to produce something. Hopefully it is beautiful (not just on the outside but inside too).  How you managed to create it (the language, test approach, etc) is secondary to the thing itself. And, oh, if it is malleable and can be adapted to do new exciting things, is that proof enough you used good coding techniques?

We spend so much time talking about the tools, we forget that it is the result that matters. We forget about the joy and awe of working code.  We instead tend to form language advocacy groups, cult-like methodologies and obsess over software licensing.

Really, if someone were to create a fully aware artificial being capable of not only passing the Turing test but able to engage us in deep conversation, would we (the programmers) nitpick over how poorly the code is structured, the lack of test coverage and how terrible it is that it was implemented in a crappy programing language?

Thursday, November 11, 2010

MP3 ID3v1 tag reading in Perl and in Haskell

I am building an MP3 jukebox for my home...

I know that I am supposed to use ID3v2, but my MP3 collection (CD ripped, Amazon and Emusic) still sports ID3v1 tags, so I thought it would be a safe  bet to just parse it.

I quickly wrote an ID3v1 tag parser in Perl (yes, I know CPAN has several solutions for this but I wanted to write my own just for the fun). Here is what it looks like:

use strict;
use warnings;
use Fcntl qw(:seek);

my @genre = (
'Blues','Classic Rock','Country','Dance',
'Jazz','Metal','New Ag(e','Oldies',
'Alternative','Ska','Death Metal','Pranks',
'Game','Sound Clip','Gospel','Noise',
'Space','Meditative','Instrumental Pop','Instrumental Rock',
'Southern Rock','Cult','Gangsta','Top 40',
'Christian Rap','Pop/Funk','Jungle','Native American',
'Cabaret','New Wave','Psychadelic','Rave',
'Acid Punk','Acid Jazz','Polka','Retro',
'Musical','Rock &','Hard Rock','Folk',
'Folk-Rock','National Folk','Swing','Fast Fusion',
'Bluegrass','Avantgarde','Gothic Rock','Progressive Rock',
'Psychedelic Rock','Symphonic Rock','Slow Rock','Big Band',
'Chorus','Easy Listening','Acoustic','Humour',
'Speech','Chanson','Opera','Chamber Music',
'Symphony','Booty Brass','Primus','Porn Groove',
'Satire','Slow Jam','Club','Tango',
'Samba','Folklore','Ballad','Power Ballad',
'Rhytmic Soul','Freestyle','Duet','Punk Rock',
'Drum Solo','A Capela','Euro-House','Dance Hall' );

my $id3v1;
my $id3v1_tmpl = "A3 A30 A30 A30 A4 A28 C C C";

while (my $filename = ) {
    chomp $filename;
    open my $fh, '<', $filename or next;
    binmode $fh;
    seek $fh, -128, SEEK_END and read $fh, $id3v1, 128;
    close $fh;
    my (undef,$title,$artist,$album,$year,$comment,undef,$trk,$genr) =
    print "$filename|$title|$artist|$album|$year|$trk|".$genre[$genr]."\n";

Basically it takes a stream of MP3 filenames over stdin, opens them and dumps out a pipe delimited summary of what it found. Here is how it is run:

$ find /home/todd/music -name "*.mp3" | perl >mp3_data.txt

Here is a line from the output (mp3_data.txt):
/home/todd/music/Charles Mingus/Ah Um/Charles Mingus_10_Pedal Point Blues.mp3|Pedal Point Blues|Charles Mingus|Ah Um|1959|10|Jazz

I am considering using Haskell for my jukebox, so I was curious what this would look like in Haskell.  Here is my newbie Haskell implementation:

import Text.Printf
import Data.Array
import Char
import System.Environment
import System.IO

-- Create a array of genres
genres = listArray (0, l-1) genres_l 
           genres_l = [
             "Blues", "Classic Rock","Country","Dance",
             "Jazz","Metal","New Age","Oldies",
             "Alternative","Ska","Death Metal","Pranks",
             "Game","Sound Clip","Gospel","Noise",
             "Space","Meditative","Instrumental Pop","Instrumental Rock",
             "Southern Rock","Cult","Gangsta","Top 40",
             "Christian Rap","Pop/Funk","Jungle","Native American",
             "Cabaret","New Wave","Psychadelic","Rave",
             "Acid Punk","Acid Jazz","Polka","Retro",
             "Musical","Rock &","Hard Rock","Folk",
             "Folk-Rock","National Folk","Swing","Fast Fusion",
             "Bluegrass","Avantgarde","Gothic Rock","Progressive Rock",
             "Psychedelic Rock","Symphonic Rock","Slow Rock","Big Band",
             "Chorus","Easy Listening","Acoustic","Humour",
             "Speech","Chanson","Opera","Chamber Music",
             "Symphony","Booty Brass","Primus","Porn Groove",
             "Satire","Slow Jam","Club","Tango",
             "Samba","Folklore","Ballad","Power Ballad",
             "Rhytmic Soul","Freestyle","Duet","Punk Rock",
             "Drum Solo","A Capela","Euro-House","Dance Hall" ]
           l = length genres_l

main = do

  hSetEncoding stdin latin1
  hSetEncoding stdout latin1

  fname <- getContents          -- lazily read list of files from stdin
  mapM print_id3v1 (lines fname)
print_id3v1 fname = do
  print fname
  inh <- openBinaryFile fname ReadMode
  hSeek inh SeekFromEnd (-128)
  dat <- hGetContents inh
  printf "%s|%s|%s|%s|%s|%d|%s\n"
       (extract 3 30 dat)      -- Title
       (extract 33 30 dat)     -- Artist
       (extract 63 30 dat)     -- Album
       (extract 93 4 dat)                              -- Year
       (Char.ord (head (extract 126 1 dat)))           -- Track
       (genres !(Char.ord (head (extract 127 1 dat)))) -- Genre
  hClose inh

-- extract and trim a range of elements from list
extract idx ln s = 
    trim0 (take ln (drop idx s))

-- Trim nulls from list
trim0 s = filter (/= '\0') s

You run it similarly. Frustratingly, it isn't very happy with filenames with non-ASCII characters :-(

$ find /home/todd/music/ -name "*.mp3" -print | ./mp3info >mp3_files.txt 
mp3info: /home/todd/Music/music/Ch�ying Drolma & Steve Tibbetts/Selwa/Ch�ying Drolma & Steve Tibbetts_05_Gayatri.mp3: openBinaryFile: does not exist (No such file or directory)

I am not a Haskell expert, but I didn't expect it to choke there...

EDIT: Fixed the filename problem by adding:

  hSetEncoding stdin latin1
  hSetEncoding stdout latin1

Tuesday, October 19, 2010

Future runtime environment for Robots

Embedded systems are getting smaller and more sophisticated. While there are currently bare ARMs and 8/16-bit micros controlling our mainstream robots, this won't do for the more sophisticated (domestic) robots of the near future.

When we consider sophisticated robots (whether ruled by a subsumption architecture or other invariably concurrent system), we won't think of Python, Java, Ruby or Perl. We will be thinking of something more Erlang-like or perhaps Unix-y.

Can you imagine jacking into your robot's debug port, typing "ps" and seeing a collection of inter-communicating processes running on a Linux kernel?  Or will it be something like Erlang/OTP?  (Erlang is the dark horse here... Unix may never go away as a platform.)

So, how about it? Erlang on a gumstix?

Friday, September 10, 2010

New AFT release!

AFT development has dormant for about 1 year, so I decided to reboot it with a minor (experimental) release (5.098) that supports Indexing. This is mostly useful for LaTeX output. I'm not sure how useful the HTML output will be.

I've also started to clean up the Perl source for AFT.  I am currently reading the new edition of Effective Perl Programming and hope to apply more idiomatic Modern Perl conventions to the 14+ year old AFT sources.

As always, AFT is available through "sudo apt-get install aft" under Ubuntu (and Debian?). But to get this new release, go to the AFT website. (For a quick look at Indexing in action, look at the aft reference manual and scroll to the last page).

I need to start archiving my art...

This is an airbrush I made 23 years ago:
Miles Davis

I need to scan in all my old artwork and figure out the best place to post them.

Wednesday, September 08, 2010

I miss Perl...

I've been going through my old books and came upon a stash of Perl tomes.  I had a love/hate relationship with Perl. I wrote AFT in Perl, but have not used it as my language of choice in (almost) a decade.

Stumbling across these books got me wondering: Where have all the Perl hackers gone?

Well, I can't say where they have all gone (Ruby? Python? Retirement?), but I miss the funky vibe that Perl had in it's day.  Perl was messy, but the language attracted the most interesting people.  I've always seen it to be the language of poets (as opposed to engineers).  Perl people loved wordplay. Perl people weren't just interested in producing interesting apps, but also making the app source code look interesting.

Well, Perl isn't gone. Apparently, strides have been made in Perl 6 and Rakudo is available for playing around with a lot of Perl 6 features.

But, will the hackers come?

I am reminded of a quote from Ratatouille (Colette introducing the kitchen staff to Linguine):
 "... So you see: We are Artists. Pirates. More than cooks are we."

Sunday, August 29, 2010

Scratch, Squeak and so Forth: Robot programming enviroments

A thought experiment...

If I was going to teach kids how to control a Roomba by way of programming, where would I start?
Outside of Squeak and Scratch, I think the most common answer involves also teaching them how to use a source code editor.

This is unacceptable.

Squeak (as derived from Smalltalk-80) and Scratch (as derived from various Logos) integrates the programming environment with the language. This isn't about just being an "IDE".

Squeak let's you hack in a workspace without concern for files. It is persistent and natural. You write a little, see how it works out and continue.  At some point you may save your workspace, but you aren't really thinking about files at this point.

Scratch has a similar (although not as radical) approach. My youngest kids  (age 7 & 7) would script for a few hours and then pick some random series of characters as a "name" to save their project into (for later recovery). Eventually, they started using more descriptive words for naming their projects. But at no time did they think about files and file systems.

I think files and editors are distractions (and not necessary ones -- unless you want to get a mainstream programming job).

Forth had this idea decades ago (and so did Smalltalk).  Forth had blocks (1K blocks to be specific) that held text and data. The early bare-metal Forths used blocks as the single abstraction from persistent storage devices (disks).  Eventually, folks "enhanced" line oriented block editing with a visual screen (with single character cursor movement!).

Forthers in the early 1980s (my self included) were happy.

Now, in 2010, I face the prospect of teaching my oldest kid (age 12 -- expert Scratcher, beginning Python programmer) how to control a Roomba via programming that require the selection and mastery of files (and file systems) -- or at least some kind of file based IDE.

Of the languages I have been looking at, Forth, Python and Lua are the front runners.

I think Forth is a more natural fit. I have just downloaded VIBE and I am being transported back 30 years.  I use to write (and extend) Forth editors like this. I am remembering how natural it felt to edit in blocks. (ColorForth continues this tradition, so Chuck Moore arguably never found much of an improvement in using file oriented environments ;-)

Forth has always made me feel "closer to the machine". Plus, with a built-in editor, I am no longer doing the context switch being external editor and Forth. VIBE (or any other Forth Screen Editor) keeps me in Forth.

I will be playing with VIBE under gforth (and perhaps extending it).  I am curious to see if this feeling is simply nostalgia or if my 23+ years of Emacs (w/ language editing modes) has been a bad move.

Tuesday, August 24, 2010

Greenspun's Tenth Rule adapted to Unix

Greenspun's Tenth Rule: Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.
can be adapted to Unix:
Any sufficiently complicated Perl, Python, Ruby, Lua, etc  script contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Unix.

And I don't mean the all of the "system" calls. I mean: concurrency, fault tolerance, data persistence, configuration and scalability. 

It may be ugly, but combine ksh93/bash, awk, bc, etc (whatever you find on a standard Unix/Linux distro) and you'll find an analog to the features offered by the above mentioned languages. This does not include "abstractions" such as fancy data structures and other syntactical sugar.   And, of course, fork/exec isn't going to beat a function call. 

However, (and this will be the subject of the next post), Unix under control of advanced shell (such as ksh93 or bash) can have the following capabilities (at least!):
  1. Coroutines (Co-processes in ksh93 or recent Bash)
  2. Communicating Sequential Processes (CSP) via named pipes and co-processes
  3. Dataflow processing (pipes)
  4. Arbitrary precision math (bc or other calculator)
  5. Reuse (command line apps)
  6. File (database) support (ls, awk, find, grep, sqlite command line, etc)
  7. List processing (command line args + ksh93/bash)
  8. Functions/apps as first class objects
And more...

Saturday, August 21, 2010

iRobot Create and Unix Programming

In my previous post I talked about using Unix as an embedded programming "language" (as opposed to a hosting environment for embedded apps).

I started to think about where to begin.  Well, let's consider the iRobot Create platform (Roomba too!).
Between your controller and the iRobot is a serial port and a binary command protocol.
If I wrote a small C app to talk over the serial port and convert to/from binary and text, I can utilize the Unix pipeline for some further down app that reads the robot's binary response as newline delimited text data.
For example:

echo "get sensors" | irobot-oi /dev/ttyS0 | some-later-app

The "irobot-oi" open "/dev/ttyS0", takes text commands as input ("get sensors"), converts it to an iRobot OI binary request, sends it, reads the binary response and converts it to text for "some-later-app".  This app could be written in C, awk, perl, etc. 

This approach is so obvious that I would be shocked to learn that no one has tried it.  I know there are libraries available the iRobot Open Interface (OI) in python and other languages, but is there a Unix command line available?

From a traditionalist Unix position, "irobot-oi" is actually doing too much.  You'd have to encode mappings between each binary command/response byte/bit and text.  A more minimal approach would be to write an even simpler binary/text converter that simply understands the protocol encapsulation and accepts/emits a comma delimited representation of the binary data. (Since the OI response protocol is directly dependent on request -- there are varying length responses with no terminator -- we have to develop some smarts into the converter.)

So, instead we would have something like this:

echo "142,2,9,13" | irobot-oi-cvt /dev/ttyS0 | some-later-app

The above command requests the state of the left cliff sensor (9) and the virtual wall detector (13) and sends the result (in comma delimited text) to "some-later-app" (which may do the actual english text mapping or simply react to the numbers).

Unix as a Programming Language - Rethink Embedded Scripting (and CSP)

As I look at eLua (on an mbed for one of my robot projects), my mind wanders... have I stumbled into another monolithic system approach?

eLua embedded systems are Lua and (maybe) some C.  I like Lua, but am I just trading one language ( Forth, C, etc) for another?

This line of thinking keeps bringing me back to Unix. Under (traditional) Unix, I have a multi-process environment connected by pipes.  I choose the appropriate language (or existing app) for the task at hand and glue it together with a shell.

Now, this would (most likely) be overkill for a small embedded device, especially in regards to power consumption. But, assume for the moment, that I had all of the Unix resources at hand and didn't concern myself with power consumption.  What would my robot controller design look like?

I design and build GPS trackers during the day. I use C and (sometimes) Forth.  I've thought about eLua, but I'd still have to write a NMEA sentence parser and fencing algorithm in a language not necessarily perfect for parsing.  How would I go about doing this if I had awk at my disposal? Or grep/sed? Or... the whole unix environment tied together with pipes under a shell.  Would something like BusyBox be a good foundation?

What is the smallest MCU (or embedded SBC) that I could run something like uCLinux and BusyBox on?
Could I do development under a fairly modest laptop Linux and port down to uCLinux and BusyBox?

Right now I am looking (again) at CSP (perhaps built upon Lua co-routines) as a mechanism for architecting embedded systems that integrate multiple (sensor) inputs.  You can also build CSP upon Unix processes (and pipes). This is the way I've done it for 25+ years.  Do I really need to cast my architecture into another monolith?
This is just me bring up Unix as a Programming Language again (but this time under the constraints of embedded computing)

Wednesday, August 11, 2010

Resurrecting BLOGnBOX

I've been thinking about resurrecting my gawk based blogging system BLOGnBOX.  I am getting tired of Blogger.

While BLOGnBOX doesn't have as many features, it lets me focus on what I want from a blog.  Although this has changed over time, I think what I currently want is:

  1. A way to publish my thoughts and ideas.
  2. An archive of my thoughts and ideas.
  3. A primary means of writing.
I am less concerned with the web aspects of a blogging system.  I'd like to have a clean, simple (yet elegantly presented) blog that I can tinker with as needed.

What led me down this path of thought is the desire to extract blog entries (or the whole blog) as a PDF document. By PDF, I really mean LaTeX or TeX quality (not just a dump).  AFT does this for me, but it might be overkill for a blogging system. Perhaps the next iteration of BLOGnBOX should  leverage LaTeX directly?

And, of course, the next iteration should be composed as a Literate Program!  (I'm leaning towards Noweb.)

Wednesday, August 04, 2010

Humans were not meant to...

Humans were not meant to sit in cubicles.
Humans were not meant to spend 8 hours a day working on reports and clicking aimlessly on the web to relieve the tedium.
Humans were not meant to be imprisoned by a workforce that wants you to do repetitive tasks mindlessly.

Humans are meant to be adventurous and creative, with bursts of brilliance (whether through exuberant play or hard knuckled persistence).
Children understand this. As adults we unlearn this. We are taught to work hard, conform for the good of society, buy a house, put away money into a 401K and make a stable environment for raising our kids. We are taught to be "wage slaves".

Sadly, most humans will never break free. But that makes it even more important that you become that rare exception (at least for a while). You have a duty to be brilliant, exuberant and adventurous. Laugh hard, fight injustice (aka stupidity), be creative and kind.

Be passionate. Don't be afraid to piss off people. Sometimes people need to be shook up.

Draw, paint, dance, program -- set an example for your kids. Let them know that it isn't their duty to conform, accept the status quo or "work for the weekend". The best thing you can do for your kids is to show them what it means to be free -- to be truly human. Brilliant, volatile and utterly unique. Take chances. (You don't have to quit your job to do this.) Just do something to express your joy, your uniqueness, your value as a human.

F*ck your boss. No, not that person you report to at work. Your real boss: the mental shackles that keeps you "in line". Break those shackles.

Not everyone can do this. But it is your duty to try.

Sometimes, when your boss isn't looking... let go.

Myforth, 8051 and minimalism

Programming in Myforth has given me a greater appreciation for minimalism.  (I suppose programming in ColorForth would be even better, but I don't have access to the proper hardware...)

Using minimalistic (simple) tools forces you to approach a problem differently.  I felt some of this back in the 80's when all I had was a little Commodore 64 and some big ideas, but coming back to minimalism from two decades of big iron is refreshing.

I now look at a problem and think "what is the simplest way to solve this?".  This takes on a deeper meaning when you consider that the tools force you to find simpler ways. When all you have is 768 bytes of RAM and 8KB of flash, you have to think in simple terms.

Take, for instance, the problem of geofencing.  I do GPS trackers (on 16-bit micros) for my day job.  I have an MSP430, 16KB of RAM and 256KB of program space (flash).  The trackers I build have a concept called geofencing. Here you define polygons or circles that affect how the GPS points are handled. Sometimes you want to log at a different rate based on the fence you are in; sometimes you want to "beacon" (transmit) at a different rate.

Programming a fence algorithm can be tricky (and computationally intensive). In addition, GPS coordinates are represented typically in (at least) scaled 32 bit values (w/ 5 decimal digit precision).

Thirty-two bit math is taxing for an MCU that only supports 8-bit math. What is a lowly 8-bit to do?
Well, if your "problem domain" only needs to deal with fences defined around just a few miles, you can truncate a lot of the math to 16 (or fewer) bits while retaining precision. Once you know that you are "in the ball park", you only need to look at the lower bits.  You don't need to consider the whole 32 bits.

This is a good example of how refining the problem domain helps generate a simpler (smaller) solution. Even if I used 16 bit or 32 bit MCUs, this can save me some processing time. (My field is "low power consumption" solutions, so saving processing time equals saving power).

Tuesday, July 20, 2010

myforth, 8051 and robotics

Just an update. I am quite taken by Charley Shattuck's myforth (click link and scroll to the bottom of the page). Porting it to an obscure 8051 part  (for  24 bit sigma-delta ADC) greatly increased my knowledge of 8051 assembly. Myforth is more of a Forth-based macro-assembler than a Forth dialect. It is both minimalistic and rich.

I got great pleasure out of implementing a moving average over 24 bit ADC samples using just 8-bit operators for the math.  It reminds me that I take a lot for granted when I toss about 32 bit integers using C on an MCU.

(I've previously used SwiftX Forthfor 8051 programming, but the part in question had only 768 bytes of RAM -- not quite enough.)

Sunday, June 06, 2010

Ideas are dangerous things...

A movement starts with an idea. A revolution starts with an idea. An invention starts with an idea.
Ideas are volatile things.
...There are thoughts enough
To blow men’s minds and tear great worlds apart 
 My thoughts were in embedded systems for the past 4 years.  Four years ago I left behind large systems development.  I went minimal -- 8-bits in fact.  Improbable as it seems, I managed to get back into Forth development. I've spent the last 8 months writing Forth code on a 16-bit MCU (MSP430).  The project is ending and the product is about to be delivered.

My thoughts now turn to vacation.  But, once on vacation, my thoughts will wander back to computers. So, what's next?

I'd like to finish my embedded system CFT projects, but of course, my mind wanders.

My mind is wandering here  and here.

A while back, I read (and mentioned)  Reaching Escape Velocity (and Gonzo Engineering).  Steven Roberts suggests that you find your all consuming project and pursue it.

The problem is, I don't have such a project in mind.
Maybe my true passion isn't making things.

I love ideas.  I think I am a programmer (rather than inventor) because I often don't need to build something. Sometimes it is just enough to think it (and most importantly share it).  Ideas are like.

So, I am not sure what I am going to do next.
So whatever your hands find to do
You must do with all your heart
There are thoughts enough
To blow men’s minds and tear great worlds apart

There’s a healing touch to find you
On that broad highway somewhere
To lift you high
As music flying
Through the angel’s hair.

Don’t ask what you are not doing
Because your voice cannot command
In time we will move mountains
And it will come through your hands  -- John Hiatt, "Through Your Hands"

Friday, June 04, 2010

Posterous... BLoGnBOX

I stumbled upon Posterous and it sounds a bit like my BLoGnBOX.
Posterous came out in 2008; BLoGnBOX went live in 2006.

BLoGnBOX was never hosted but the concept is the same: Email to Blog posting.

Posterous recently announced Markdown support.
Markdown is very similiar to my own AFT.

Wednesday, June 02, 2010

WikiReader Data Logger

A quick hack. Here is a data logger I wrote for the WikiReader that I use at work. It uses my previously discussed WikiReader Serial port hack:

160 constant max-line-chars
variable byte
create line-buf max-line-chars chars allot
variable lbcnt
variable fd
variable linecnt

\ Base logfile
: logfile s" log.000" ;

\ Create a new logfile with new 3 digit numeric extension 
\ (e.g. log.001)
: gen-logfile ( nnn -- caddr u) 0 <# # # # #> logfile + 3 - swap drop 3 cmove logfile ;

\ Does this log file exist or is it available (free)?
: logfile-free? ( caddr u -- f) r/o open-file ?dup if drop 1 exit then close-file drop 0  ;

\ Iterate through to a free logfile. 
\ We support up to 1000 log files before we fail.
\ (Need a failure handler!)
: next-logfile ( -- )  999 0 do i gen-logfile logfile-free? if unloop exit then loop ;

: wiki-logger ( -- )
    0 lbcnt !
    logfile w/o create-file ?dup if 
        cr lcd-." Can't create log: " lcd-.  drop exit
    fd !
    logfile lcd-type lcd-cr
    lcd-." Ready. Press any button to exit." lcd-cr lcd-cr
        \ sleep only between lines
        key? 0= lbcnt @ 0= and if wait-for-event then 
        key? if
            key dup line-buf lbcnt @ + c!  1 lbcnt +! ( -- c)
            10 = if 
                line-buf lbcnt @  2dup fd @  write-line drop
                lcd-type lcd-cr
                0 lbcnt !
        button? if
            \ A button was pressed so clean up 
            \ and exit.
            fd @ close-file
        ctp-flush   \ not interested
    again ;

Thursday, May 27, 2010

WikiReader Serial Port Hack Pictures

Per a recent request...

Here are some pictures of my small hardware hack.

First, I just added 3 header pin sockets to the already exposed debug port:

But that proved too cumbersome to maintain a good tethered connection to my laptop (plus the batteries would have to be exposed).

So, with the aid of a master machinist (Sandor -- a co-worker), I put a stereo "micro" jack on the top side of the device:

Here is the finished result:

You can see where I (badly) pried open the case ;-)

And here is where I am today:

Now, onto software...

Wednesday, May 19, 2010

So many CFT projects...

  1. Hands-off! - Small, mountable, personal alarm system. Attach to a bike, briefcase, computer bag, etc. Arm/Disarm with a key fob. Piercing alarm when someone "moves" your possession. Key fob also has a smaller alarm/buzzer to notify you (up to 10 meters away).
  2. mooTracker - Ultra low power GPS tracker for livestock, pets, etc. Can be used with GSM/SMS module, Iridium modem, etc. Uses an accelerometer to detect motion before engaging GPS trackers. Standby current should be <>
  3. UV Index Clip - Small (discrete) UV Index sensor (1" square max). Uses a button cell battery, SiLabs C8051F930, and ANT for communication to iPod/iPhone/Pocket-device to alert you when you've had enough rays. Can be clipped to clothing or hat.
  4. Crop/Garden moisture monitor. Seed your garden (co-op, winery, etc) with low cost, very low power wireless sensors. They contact a hub (with GSM/SMS capability) to send you status/alerts as text messages. The hub should also support data logging/consolidation for summation or later retrieval.
  5. Portable Power Consumption Data Logger. The key word is "portable" here. This data logger/monitor is designed to be used "in the field" with portable devices (sensors, auto accessories, robots, etc). Mainly for battery powered devices. Should be able to measure power consumption between 0-12volt and between 1uA and 3A.
  6. WikiReader Portable Terminal - Use the WikiReader as a local/personal display and a controller of UART enabled devices. Maybe use Bluetooth to use it to query/control sensors.

So many CFT projects, so little time. Is there a way to tie them together?
Is there a common theme?

If I only built the things that "I" find useful, which would they be?

I could use #4 in my yard and I have friends that would find it useful.

My wife could use #3....

I could see where #1 would be useful, but it generally sounds pretty boring
(from an implementation point of view).

None of these projects are terribly unique. Maybe my approach is
"low cost / low power". I find it challenging to do a lot with a little.

Tuesday, May 18, 2010

Gonzo Engineering

This manifesto strikes a chord. I am not as brave (or insane?) as Steven Roberts, but I do find resonance with his writings. I remember briefly encountering Roberts at InterOp Spring 1992 where he had a booth showing off his BEHEMOTH bike.

I just finished his book.

I need to do more about my crazy dreams.

Sunday, May 16, 2010

WikiReader, Forth and Hacking

It's old news, but I find the WikiReader very cool. It is an "offline" pocket size wikipedia reader (searches a mini-SD card of a wikipedia dump). It came out last fall (2009) and it has already been subject to a teardown and random hacks. What finally got me interested is knowing that it runs a cross compiled (almost ANSI) Forth.

I've been doing a lot of low level and high level Forth recently and wanted a "lighweight" hackable device for some mall programming (my 11 yr old son plays Warhammer 4K at a local mall and can be engaged for up to 3 hrs -- ugh, 3 hrs of waiting in a mall). The problem with most of my devices is that they have lots of wires, bare boards and LEDs. I don't need the attention (blinking LED.. somebody call the police!).

So, I got me a WikiReader and I've already opened it up to hack in a connector for a serial port (pictures later).

The toolchain and source code is free (developed under Linux w/ open source tools), so I installed ubuntu (once again: goodbye windows) and was quickly cross compiling new Forth engines!

More later, but some quick mini-stats:

The device works off of 3 AAA batteries and draws 11-13mA (avg) while "idle" (waiting for a touch screen or serial event) and 80-90mA (avg) while searching, handling I/O and doing wikipedia stuff.

Not bad.


Wednesday, April 28, 2010

myforth, 8051 and iRobot Create

At the end of my previous post I entertained the idea of using a SiLabs C8051 for controlling the Create. Of course, I can't run Lua on that MCU, so the obvious alternative is Forth.

But which Forth? I have a copy of SwiftX for the 8051, but I decided to look at an interesting environment called MyForth that i found here. This is the, quite detailed, manual.
Its non-standard (I don't really care), influenced by colorforth (yeah!) and completely tied to the 8051.

In this day and age, who would use a language completely tied to a platform? Well, apparently, the point of MyForth was to produce a true 8-bit Forth that would match the 8-bit nature of the 8051. (Most 8051 Forths are 16-bit, while the registers and most efficient instructions on the 8051 are 8-bit based.)

After a while, I started to think: so what? As modern programmers we've embraced portability over efficiency. No, its more that that: We strive to avoid software that locks us to a particular piece of hardware.

Is this a real problem (all of the time)? If I want to augment Create (or other consumer robots) with an MCU and some code, should I strive to make it portable? Or do I just concern myself with the problem at hand: Making the robot do interesting things.

Another plus for MyForth is its development environment: It uses gforth as a cross-compiler. I have full access to the cross (meta) compilation. I can craft MyForth to become "my forth". So, who says I can't re-target it for another MCU? Or, at the very minimum, use it as a model for cross-compilation.

Interesting reading and hacking for the weekend.

Saturday, April 24, 2010

eLua and mbed and iRobot Create

Mbed is 5V tolerant. This means I should be able to connect a board directly to the iRobot Create that has been sitting gathering dust for a couple of years. I couldn't get motivated to write in C for it; I didn't have a viable Forth option at the time (although now I do).

Since the Create sucks big power as it is, the addition of an mbed shouldn't be a problem.

While I am quite deep into Forth these days, development may be better suited for eLua (since it is free). Maybe? Something to think about.

Of course, the SiLabs C8051F340x is also fully 5V tolerant (including power supply) with fewer external circuit requirements and much lower power consumption. I can't run eLua on it, but I've got my trusty SwiftX 8051 Forth....

So many options, so little time.

eLua and mbed

Sometimes I get lost in the whole "low power" thing. I've been focused so much on power saving processors that I forget what fun it is to just program. Forth is great for getting the job done, but sometimes I just want to play around with algorithms and want something a little more... infix.

So, eLua fits the bill, especially on mbed. (Lua on Cortex-M3! Yay!)

Monday, April 12, 2010

mbed (Cortex-M3) and MPE Forth

Mbed is a neat little NXP LPC1768 based Cortex M3 development environment. It has a web based IDE, but I'm not interested in that. You can flash it by dragging a *.bin file to its embedded flash drive. Once you drag, you reset (via pushbutton) and a second or two later the device is reprogrammed.

This made a nice target for MPE's Forth 7 Cortex-M3 cross compiler. (I purchased the inexpensive "Stamp" version for ~ $115).

There was no included Mbed support, so I attempted a port. The port was easy -- I got the LEDs to blink. Now to figure out what to do with the thing...

While the LPC1768 has some interesting low power modes, the extra programming/flash-drive circuitry of the mbed doesn't allow full exploitation. However, until the Gecko Starter Kit becomes available, the mbed will do (for development purposes).

Saturday, March 13, 2010

SiLabs C8051 and SwiftX Forth

It's been a while since I've posted... I am very busy these days. :-(

I am currently playing with SiLabs C8051F344 with a purchased copy of Forth Inc's SwiftX (under Windows -- my Linux development effort never fully cooked).

I am impressed with the speed of this "lowly" 8051 derived 8-bitter. It isn't meant to do big things, but for small things it fairly rocks.

I've previously played with the C8051F93x very lower power MCU, but given my current interests (GPS tracking), the difference in power consumption between that very low power part and the more power hungry F344 is minimal. The GPS consumes so much current when running that the MCU is just "noise" in any power chart plots.

When asleep, the difference between consuming 1uA (sleep mode) on the F93xx vs 25-50uA on the F344 (clocking way down to around 40Khz) is not worth considering (we are talking years of battery life for either).

More on my current project later... but for now I am just enjoying crafting Forth on a 8-bit MCU :-)

Tuesday, January 05, 2010

SwiftX Forth and 8051 and Linux

Maybe 3 other people in the world would probably be interested in hearing that I have gotten the evaluation copy of SwiftX Forth running under Linux (Wine) talking to Silab's USB Toolstick's C8015F931 daughter card.

I had to steal the daughter card UART and re-route it to a separate USB->UART bridge for SwitfX's XTL (programming still works through the Toolstick), but it all works (so far) under both Windows and Linux (Ubuntu!).

I am playing around with 8051s because I am feeling retro and a bit weary of the TI MSP430 family. The C8015F931 has some impressive low power numbers and some neat features to make even a lowly 8051 appealing.

I have to remember to do a post on my newest interest: Augmenting sensors with tiny low power MCUs to make them smarter.