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  Coffee Making
  Fotis Georgatos <>
  V1.0  2004-08-29

  One of the most memorable comments about software ever said is whether
  this or that piece of code can make coffee. Coffee is a world commod�
  ity that is second only to oil. Linux DOES make coffee; and it tastes
  good as well!

  Table of Contents

  1. Introduction

     1.1 Copyright
     1.2 Disclaimer
     1.3 Version
     1.4 Translations
     1.5 Credits
     1.6 What do you drink/smoke while writing this?
     1.7 Feedback

  2. Menu

     2.1 French
     2.2 Nescafe
     2.3 Frappe'
     2.4 Freddo
     2.5 Espresso
     2.6 Cappuccino

  3. Hardware

     3.1 Driving voltage 0-5V from the computer
     3.2 Controlling with a Relay
     3.3 Controlling with TRIAC #1
     3.4 Controlling with TRIAC #2

  4. Software

     4.1 Programming
     4.2 Device driver
     4.3 Connecting with the Internet

  5. Building the Turing Complete Coffee Machine

     5.1 An adequate assembly language
     5.2 Hardware and interfacing
     5.3 Software
     5.4 A minor criticism on the Turing Machine

  6. Overdose symptoms

  7. Expansions

  8. Further Information


  1.  Introduction

  For a long time humanity has been wondering how could a computer make
  People need coffee to wake up, and stay awake for a long time in front
  of the computer.  It is common wisdom that coding is better at night!

  The main trick is interfacing a coffee machine to the computer, so
  that it can be controlled by software. This HOWTO will show you how to
  do so.

  At first, it demonstrates an ON/OFF switch implemented as an
  electronic circuit which controls the coffee-machine's power supply.
  Another chapter will tell you the secrets of building intelligent,
  Turing Complete suitable, coffee machines!

  This HOWTO was initially written as part of a debate in the mailing
  list linux-greek-users, on whether linux can make coffee or not. It
  then became an article in our online magazine called magaz.  Just in
  case you wondered, magaz is in Greek and it will surely look like that
  to you!


  1.1.  Copyright

  Copyright � 2004-08-29 by Fotis Georgatos.  You are free:

  �  to copy, distribute, display, and perform the work

  �  to make derivative works

  �  to make commercial use of the work Under the following conditions:
     Attribution. You must give the original author credit.  Share
     Alike. If you alter, transform, or build upon this work, you may
     distribute the resulting work only under a license identical to
     this one.

  �  For any reuse or distribution, you must make clear to others the
     license terms of this work.

  �  Any of these conditions can be waived if you get permission from
     the author.

  1.2.  Disclaimer

  Use the information in this document at your own risk. I disavow any
  potential liability for the contents of this document. Use of the
  concepts, examples, and/or other content of this document is entirely
  at your own risk.

  All copyrights are owned by their owners, unless specifically noted
  otherwise. Use of a term in this document should not be regarded as
  affecting the validity of any trademark or service mark.

  Naming of particular products or brands should not be seen as

  You are strongly recommended to take a backup of your system before
  major installation and backups at regular intervals.

  1.3.  Version

  The Coffee HOWTO is now called Coffee Making HOWTO and heads for
  release v1.0, which will first appear somewhere here:

  It is about time for everyone to know that Coffee Making is just one
  of the standard features that come for free with *any* Linux
  distribution.  Or, does SCO have a patent on that, too? Gee...

  1.4.  Translations

  You should be able to easily find a translation of this or previous
  versions of the Coffee Making HOWTO in the following languages:

  �  Chinese

  �  Japanese

  �  Russian

  �  Indonesian

  �  Italian

  �  Polish

     and hopefully many more... (Spanish and Portugeuse anyone?)

  1.5.  Credits

  �  Ethiopia: Identified as the originating country of coffee.

  �  Coffee was popular in the Middle East for ages, until a failed
     invasion of the Turks at the city of Vienna at 1683 left behind
     sacks with strange brown beans nobody wanted:

  �  Kostas Lialiambis is the one who dared claim he can't make coffee
     with his Linux box, back then in year 1997.

  �  Panagiotis Vrionis et al for giving me interesting and humorous
     notes and let the ball roll in the early days.

  �  NUMEROUS people on the internet with additions and remarks.  Thank
     you all, really!  Even though I might have not replied to your

  1.6.  What do you drink/smoke while writing this?

  Well, to the best of my knowledge, this is a dope-free work.

  But, I can tell you the secret of the music playing on the background:
  nearly any song spelled by Zampetas or Mpithikotsis (bouzouki and

  1.7.  Feedback

  For your online commentary of your own DIY Coffee Machine steer at

  If you still have comments to say, emails get lost these days, so why
  not send me a postcard with a picture from your great hometown, adding
  a recommendation of your favourite cafe' in the area?

       Fotis Georgatos,
       Aliartou 32,
       TK 11142 Athens,


  �  Your suggestions won't be wasted, I really tend to travel quite a
     lot these days and might be around before your realize it.

  �  Yes, I have been in Amsterdam and even lived there for three years;
     coffee shops generally don't account as cafe's!

  �  Surprise: I actually prefer chocolate and tea over coffee. ;-)

  2.  Menu

  2.1.  French

  Popular coffee among programmers because it doesn't need a lot of care
  and its cooking is streamlined; just like commercial software.  Its
  exciting taste has inspired thousands of programmers in writing
  incredible software, written in the very first hours of a day.  M$
  Windows for example has been written at 5:00 o'clock in the morning,
  only thanks to coffee! A similar result is guaranteed.

  2.2.  Nescafe

  Nescafe is a rather strong coffee, made by pouring hot water in a
  mixture of coffee, sugar and some water.  You usually take 1 spoon of
  coffee and 1 spoon of sugar with just a bit of water, to mix it. In
  the meantime you should have the water boiling. As soon as the water
  is hot enough, you mix them all together and preferably add condensed
  milk.  Although you could use something simpler than a coffee-machine
  to boil the water, I have seen this done so several times...

  2.3.  Frappe'

  A popular variation of the above mentioned coffee.  Actually, you
  don't need a sophisticated coffee-machine, rather a refrigerator for
  cold water and ice-cubes.  It is very popular in South Eastern Europe
  during the warm summer months.

  2.4.  Freddo

  This is a complicated one, read coffee-faq (read further information)

  2.5.  Espresso

  Espresso is a very strong, italian sort of coffee.  You serve it in
  small cups (You ask why? See chapter: Overdose Symptomes) with one or
  two pieces of lump sugar.  To produce a good espresso you need fresh
  grinded coffee beans, water, lump sugar and a special machine. These
  machines boil the water and press the very hot steam through the
  grinded coffee beans. You can buy a super-duper-automatic machine for
  a lot of money.  But a low cost machine is usable, too.

  OK., lets start. Fill water in your machine. Let it become hot. In the
  meantime fill about 1 teespoon of coffeepowder in the filterhandle of
  your machine. Press the coffeepowder down. Not too much. Now the water
  is at the right temperature. Attach the filterhandle to the machine
  and let the machine work. After about 30 seconds you can serve a
  delicate, hot espresso. It is fine after a good meal. You feel good
  and can code for a few more hours.

  2.6.  Cappuccino

  (See also chapter: Espresso) If you have a more profi-like machine,
  you can use it, to froth milk with it. You need this feature to make a
  creamy sort of coffee. It is easy to prepare. Put some frothed milk in
  a coffee pot and fill it up with espresso. Then decorade with some
  chocolade flakes. That's it.

  3.  Hardware

  A generic diagram could look like this:

       ---------   0-5V  ---------  ~220V   ----------------
       |  PC   |====>====|Circuit|==========|Coffee-Machine|
       ---------         ---------          ----------------

  The concept is that we take a controling voltage from the computer,
  which drives an electrically isolated circuit with a Relay or Triac.

  You must choose a Relay circuit, if you have a coffee-machine greater
  than 200W. You can use a triac-based one if your coffee machine isn't
  high power.

  All circuits presented are tested, but the results and risks are YOUR
  OWN RESPONSIBILITY.  If you have no experience with electronics you
  should NOT try building it on these, otherwise you may get a bad

  You should be very careful while experimenting with 220V, and using an
  appropriate fuse is absolutely advisable.

  3.1.  Driving voltage 0-5V from the computer

  Here is a simple example to get a voltage 0-5V from the parallel port
  of the computer.

             Back View          -----    Pin 10 - ACK
             Male DB-25         |   |    Pin  9 - D7
             Connector          |   |                           Pin 2 - D0
                                v   v                           v   Pin 1 -
             /                                                            \
             \     13  12  11  10   9   8   7   6   5   4   3   2   1     /
              \                                                          /
               \     25  24  23  22  21  20  19  18  17  16  15  14     /

  Pin 1 is Strobe (inverse logic)

  Pins 2-9 is DATA BUS's signals, exactly what was written to the
  parallel port's latches with an OUTB command.

  Pin 10 is the acknowledge signal (ACK), controlled by you, so that you
  can produce an interrupt to the CPU.

  Pins 18-25 are short-circuited and this is the ground (GND).

  In detail:

       <= in   DB25    Cent    Name of         Reg
       => out  pin     pin     Signal          Bit     Function Notes
       ------  ----    ----    --------        ---     -----------------------------
       =>       1       1      -Strobe         C0-     Set Low pulse >0.5 us to send
       =>       2       2      Data 0          D0      Set to least significant data
       =>       3       3      Data 1          D1      ...
       =>       4       4      Data 2          D2      ...
       =>       5       5      Data 3          D3      ...
       =>       6       6      Data 4          D4      ...
       =>       7       7      Data 5          D5      ...
       =>       8       8      Data 6          D6      ...
       =>       9       9      Data 7          D7      Set to most significant data
       <=      10      10      -Ack            S6+ IRQ Low Pulse ~ 5 uS, after accept
       <=      11      11      +Busy           S7-     High for Busy/Offline/Error
       <=      12      12      +PaperEnd       S5+     High for out of paper
       <=      13      13      +SelectIn       S4+     High for printer selected
       =>      14      14      -AutoFd         C1-     Set Low to autofeed one line
       <=      15      32      -Error          S3+     Low for Error/Offline/PaperEnd
       =>      16      31      -Init           C2+     Set Low pulse > 50uS to init
       =>      17      36      -Select         C3-     Set Low to select printer
       ==      18-25   19-30,  Ground

  3.2.  Controlling with a Relay

  The straight-forward circuit one can build is:

                                     |    __|__
                                   Relay   /^\  Diode 1N4002
                                    Coil  /---\
                                     |      |
                                  | /
                        4.7K    B |/  C
       parallel port >-\/\/\/\/---|        NPN Transistor: BC547A or 2N2222A
       data pi                    |\  E
                                  | \
       parallel port >--------------+
       ground pin                   |

  Connect Vcc with the same voltage as the relay type (usually 5 or
  12V).  Obviously, the relay's specifications should be scaled for your

  Barmen, tend to put the relay AFTER the transistor, at the emitter (E)
  pin instead of the collector (C) pin. This is bad practice because it
  biases the transistor badly, and might result in bad coffee :-).
  Diode 1N4002 is useful to protect the transistor from the relay's
  currents.  If you don't use it the transistor will sooner become dark
  and smelly...

  3.3.  Controlling with TRIAC #1

  If you only want a simple circuit, you can use Motorola's triac driver
  MOC301[012], together with a general purpose TRIAC like SC141D.  This
  method has the advantage that you don't need any extra power supply.

  For non-inductive loads, this is the circuitry:

               270     1 +-------+ 6    180
         +5v -VAVAVA-----+       +----VAVAVA-----+-------------- Line Hot
                       2 |  MOC  |               |
         TTL in ---------+ 3012  +nc            VA  SC141D
                         |       | 4           / |
                       nc+       +------------/  |
                         +-------+               +----\/\/\/---- Line Neutral

  If you are going to work with 220V, try to obtain a 3021.  Inductive
  loads should be used in conjuction with bypass capacitors, better
  consult Motorola Application Note AN-780.  Coffee-machines are mainly
  resistive loads and not inductive (like a motor), but who knows what
  yours is?

  3.4.  Controlling with TRIAC #2

       |    180                      180            2.2k
       +---/\/\/\----+-----+   +----/\/\/-+--/\/\/\---+-------> 120V
                     |    1|   |6         |           |         Hot
                     |    +=====+         |           | MT1
                     |    | MC  | TRIAC   |          +-+
                     |    | 3032| Driver  |        G | | TRIAC
                     |    +=====+         |         /| |
                     \    2|   |4         |        / +-+
              2N3904  |----+   |          |        |  | MT2
                     /     |   +--------- | -------+  |
                    V      \              |        |  |
                    |      /              |        \  |
                    |      \ 43    .01u  ---   10k /  |
                    |      /       500V  ---       \  |
                    |      |              |        /  |
                    +------+              |        |  |            Neutral
                    |                     +--------+--+---o    o--> 120V
                    /                                      load
        >-/\/\--|  2N3904

       This design is for 120V. You should change resistors accordingly for 220V.

  Circuit description:

  The MC3032 is an optoisolator TRIAC driver.  The 180-ohm resistor sets
  the current for the LED emitter in the optoisolator.  Change the value
  of this resistor - if necessary - to get a reasonable current (e.g.,
  15 mA).

  Note that you cannot test this circuit without a load.  The TRIAC will
  not switch unless connected to an AC voltage source, so you can't test
  it for simple switching without applying AC and a load. Note the 500V
  rating on the .01 capacitor.

  4.  Software

  4.1.  Programming

  You will have to build an executable that will take the following

  �  Get permission to use I/O address space, by calling kernel, with
     the call ioperm: eg ioperm( BASE, range ,1);

  �  Perform an out request instruction, to set the 0-5V voltage to the
     parallel port, eg outb( 1, BASE );

  �  Wait enough time so the coffee is made. It would be nice if that
     time is read by looking at the command line.

  �  Then it will turn off the coffee-machine: outb( 0 , BASE );

  �  Before ending it should give back the parallel port with an ioperm(
     BASE, range, 0);

     Change BASE = 0x3bc for /dev/lp0, 0x378 for /dev/lp1, and 0x278 for
     /dev/lp2; range=8.

  It would be useful if you had that program setuid, so that everybody
  can drink coffee! You BOFH!

  4.2.  Device driver

  Just read kernel hacker's guide, to implement a device driver; you
  might also do it in user space.  Please compile it as a module, so
  that we won't need a kernel compile in every update.  Then write:

  echo cappuccino >/dev/coffee

  And you will have a hot cup of coffee in minutes!  Remember to give
  the right permissions to /dev/coffee, depending on whether you want
  only root making coffee or not.

  The advantage of this method is that it supports feedback from the
  coffee-machine by using the ACK of parallel port and such, so that
  smart coffee-machines can produce an interrupt when ready.

  Do it yourself, after reading the excellent book of Alessandro Rubini
  and Jonathan Corbet Linux Device Drivers and studying the Cross
  Reference Linux source code repository.

  4.3.  Connecting with the Internet

  If you have implemented the controlling program in C (see above), you
  just have to write a CGI script to turn ON and OFF the coffee-machine
  or pass along more complex instructions.  You should write some nice
  webpages, explaining how to make coffee, and put them on an apache web

  ...LAMP technology (Linux, Apache, MySQL, [Perl|Python|PHP]), will
  help you to build a perfect user-customizable coffee system!

  At some time in the future when the applications get rather complex,
  you might want to extend on the basis of Flow-Based Programming:  What a great match for a great
  Coffee Machine!
  5.  Building the Turing Complete Coffee Machine

  Do you pine for the nice old days, when men were men and build their
  own coffee machines?

  This chapter is about assembling a smart, intelligent!, coffee
  machine.  It will be a computer designed with a von Neumann
  architecture, comprised of a CPU, ROM/RAM and I/O and will also be
  suitable for generic use, a.k.a. Universal Turing Machine.

  5.1.  An adequate assembly language

  Unlike other complex, but popular, systems that are either CISC or
  RISC, our machinery will be MISC: Mono-Instruction Set Computer!

  Alas, our processor will understand just one command and yet, given
  enough memory and time, it is able to perform any action that your
  3GHz Pentium IV could do, or just simulate it alltogether; It can
  solve any computable problem by running simple code like this:

       SBN     $mem1, $addr1
       SBN     $mem2, $addr2
       SBN     $mem3, $addr3
       SBN     $mem4, $addr4
       SBN     $mem5, $addr5
       SBN     $mem6, $addr6

  The magic command is called SBN $mem, $addr (Subtract and Branch if
  Negative), and does take the value of a memory cell $mem, subtract it
  from the accumulator (A is the only available register in this
  architecture) and store it back to the accumulator and memory $mem :
  [mem] <= A <= A-[mem].  If the result is negative, and only then, it
  jumps to the designated address $addr.  If $addr points to the next
  command, there is no conditional jump.  Now, with that command at hand
  you can subtract, add, zero memory addresses, move bytes around,
  multiply, compare and so on, so forth.  What's best of all, you can
  easily build an optimizing compiler.

  Voila. This is a great system for any Turing Complete problems plus,
  it is even simpler in coding than the original Turing Machine!

  5.2.  Hardware and interfacing

  The great thing with this innovative MISC processor is that you need 0
  bits to store the opcode of your commands. This makes your CPU much,
  much simpler: you only have to read a couple of operands each time.
  You might wish to extend the capabilities of your processor by
  extending the SBN instruction to 3 or 4 operands, so that it can
  directly load and store data from main memory.  This is an exercise
  left to the reader; kudos to google.
  The CPU diagram looks like this:

       <========= ADDRESS BUS ==============>
               =                =
               =  +---------+   =
               =  | CONTROL |   =
          +---------+  +-----------------+
          | ALU & A |  | Program Counter |
          +---------+  +-----------------+
               =  |  LOGIC  |   =
               =  +---------+   =
               =                =
       <=========== DATA BUS ===============>

  Now, all you have to do is just hook together some memory chips, for
  example by recycling static cache RAM from old 386 PCs, an ALU and a
  few glue components. You may pick one of TTL or CMOS for logic gates
  and latches; I'm a CMOS guy, but this really depends on your favourite
  flavor.  You may build an 8, 16, 32, 64 bit or whatever width system
  you need.  Just in case, for larger word widths, I have found
  preferable building the ALU with pre-programmed 27128 EPROMS instead
  of the harder-to-find 74x181s. Look around for a carry propagation
  unit, too.

  The monolithic nature of this system allows only memory-mapped I/O,
  and requires special design provisions for bidirectional interfacing,
  but nothing more peculiar than what is seen in older-generation
  systems.  AGC, the computer that drove Apollo 11 mission to the moon
  was making use of such techniques, so it should be sufficient in this
  case, too.

  Note that the data bus has to be exactly as wide as the address bus,
  that implies that the notion of a byte is only applicable to 8 bit
  coffee machines, which you will eventually find that it is more of a
  feature than a bug.  You will be surprised with what a coffee you can
  have for 8 or 16 bits bus!  It is really a general-purpose piece of
  hardware, built for peanuts.

  5.3.  Software

  Such a pure system will make a good fit together with the, famous for
  embedded systems controlling, FORTH programming language.  The major
  prerequisite for doing so is to have a stack mechanism, which in this
  case can be constructed by a counter combined together with a memory

  If you want to claim a serious coffee development platform, C
  portability is an absolute must nowadays.  Your choices might be
  hacking one of gcc, lcc or sdcc, which with proper tweaking at the
  back-ends will be able to spit out the specially crafted MISC assembly
  code.  One day you might even want to rewrite another language like C,
  forget the D letter - it is taken already, so do not make again the
  same mistakes with your compiler please:

  Just in case you thought of writing your own compiler, please read in
  advance about flex, yacc and just a little bit of related theory.  In
  particular you will quickly appreciate Noam Chomsky's taxonomy on

  �  regular grammars (the abstract formalism for regular expressions),

  �  context free grammars (any BNF-described language is such) so on,
     so forth. Read ahead on Computability Theory.

  5.4.  A minor criticism on the Turing Machine

  Because of the way a Turing Machine works (see for that ), it is a very
  complicated device to program, and debug at the end of the day.  The
  reason is, that its behavior is a sequential process that is
  completely determined by the following parameters:

  �  (1) the State the machine is in,

  �  (2) the Symbol (or number) on the square it is scanning, and

  �  (3) a Table of Instructions

  The major contemporary disadvantage of the Turing Machine (TM) is that
  it is of sequential nature, which implies that only a particular range
  of problems can be mapped to it in a straightforward way.  TMs are
  suitable for problems that are described well on a serial storage
  medium (tapes) and don't make use of indexes for data reference.  This
  is in contrast to the Coffee Machine (CM) that can handle any Random
  Access algorithms as well (with no compromise of simplicity).

  Add to this, that TMs impose a very high and unnecessary complexity on
  item (3) in favor of keeping (1) and (2) simple.  And just in case you
  don't agree that the so called Table of Instructions gets trully
  overwhelmed, have you ever tried to write a compiler for a Turing
  Machine?  A system that isn't easily programmable and is hard to
  debug, should be considered a seriously questionable system, at least
  as far as Computer Engineering (!= CS) is concerned.  For instance,
  try to simulate the Coffee Machine with a Turing Machine and vice
  versa.  Hey, if you still disagree, show me the code.

  Bottom Line: The Coffee Machine (CM), is a much better model for the
  von Neumann architecture and has a O(1) relationship with what is
  standard practice of weighting algorithms, in the current form of
  complexity theory.

  6.  Overdose symptoms

  �  excitement

  �  nervousness

  �  insomnia

  �  tachycardia or cardiac arhythmia

  �  restlessness

  �  Hypersensibility to light

  �  Annoyance in respect with various audio stimuli

  �  gastrointestinal disturbance

  7.  Expansions

  �  All hardware and software described here, can be expanded so that
     it will support toast, beaf, applepies, etc.

  �  Cluster with 8 coffee-machines. This will let you have coffee even
     when the first one gets off. Of course there will be a perfomance

  �  Parallel vector coffee-machine will be a future release.

  �  If you want the maximum automation you'll need more circuits and
     sensors, so that you can control water flow, temperature, coffee
     quantity etc.

  �  In the near future we will implement SNMP features.

  �  Serial coffee-machine at 115Kbps.

  8.  Further Information

  � This is most
     known Internet's Coffee-FAQ

  � Caffeine and
     effects of on the Nervous System

  � A pretty
     comprehensive, if informal, history of humans' interaction with the
     coffee plant.  People have been chewing coffee berries in Africa
     for 100,000 years or so.  Coffee was definitely growing in Yemen,
     where it is not native (so must have been planted), in 525 AD.

  � RFC2324: Hyper Text Coffee
     Pot Control Protocol (HTCPCP/1.0)

  � RFC2325: Definitions of
     Managed Objects for Drip-Type Heated Beverage Hardware Devices
     using SMIv2

  � Programming of
     I/O ports under popular operating system Linux.

     A lot of circuits in ASCII. Some of them are for parallel port.

  � Whatever you
     wanted to learn about a parallel port and didn't dare to ask.

  � How to write your
     own device drivers. Come on, go ahead!

     Tomi Engdahl's web page is a *must see* for everyone who enjoys

     Coffee-machines on-line. Unfortunately, there are no benchmark

  � This coffee-machine
     offers only cappuccino. It has to be upgraded!

  � Hot coffee from the the The

  � The Trojan Room Coffee

  � CoffeeCAM

  The list of links in this chapter, often becomes outdated, therefore
  you might wish to use the excellent Way-Back Machine to find them

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