JA :: Just Articles

  Fotis Georgatos, 
  Annie Pinder, 
  v0.8, 30 November 2000

  One of the most memorable comments about software I have ever heard,
  is whether this or that can make coffee.  Coffee is a world commodity
  that is second only to oil.  Linux DOES make coffee. And it tastes
  good, as well!

  Table of Contents

  1. Menu

     1.1 French
     1.2 Nescafe
     1.3 Frappe
     1.4 Freddo
     1.5 Espresso
     1.6 Cappuccino

  2. Electronic circuit

     2.1 Driving voltage 0-5V from the computer
     2.2 Controlling with a Relay
     2.3 Controlling with TRIAC #1
     2.4 Controlling with TRIAC #2

  3. Software

     3.1 Software
     3.2 Device driver
     3.3 Connecting with the Internet

  4. Overdose symptoms

  5. Expansions

  6. References

  7. etc

     7.1 preface
     7.2 Authorship and maintenance
     7.3 Copyrights
     7.4 Credits


  For a long time, humanity was wondering how could a computer make
  coffee...  People need coffee wake up and stay awake in front of the
  computer for a long time.  Everyone knows that coding is better at

  The main problem is how to manage the coffee machine with the
  computer, so that it will be controlled by software.  This generally
  means an ON/OFF switch implemented as a circuit which controls the
  coffee-machine's power supply.

  This HOWTO has turned out in a public project, look at

  1.  Menu

  1.1.  French

  Popular coffee among programmers because doesn't need a lot of care;
  like commercial software.  Its exciting taste has inspired thousands
  of programmers in writing incredible software, written in the very
  first ours of a day.  Windows for example was written at 5:00 o'clock
  in the morning, Due to coffee! A result is guaranteed.

  1.2.  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 milk.
  Although you can use something simpler than a coffee-machine to boil
  the water, I have seen this done many times...

  1.3.  Frappe

  A popular variation of the above mentioned coffee.  Actually, it
  doesn't need a coffee-machine, rather a refrigerator for cold water
  and ice-cubes.

  1.4.  Freddo

  This is a difficult one, read coffee-faq (see references)

  1.5.  Espresso

  Espresso is a very strong, italian sort of coffee. You serve it in
  small cups (You ask why? See chapter: Overdose Symptomes) with on or
  to 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 useable, 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.

  1.6.  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
  chokolade flakes. Thats it.

  2.  Electronic circuit

  A general diagram is 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 are YOUR
  RESPONSIBILITY.  If you have no experience with electronics you should
  NOT try these, otherwise you may get a bad one...

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

  2.1.  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

  2.2.  Controlling with a Relay

  The simplest circuit that one can build is:

                                     |    __|__
                                   Relay   /^\  Diode 1N4002
                                    Coil  /---\
                                     |      |
                                  | /
                        4.7K    B |/  C
       parallel port >-\/\/\/\/---|        NPN Transistor: BC547A or 2N2222A
       data pi                    |\  E
                                  | V
       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 may 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 become dark and smelly...

  2.3.  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 an 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, see
  Motorola Application Note AN-780.  Coffee-machines are mainly
  resistive loads and not inductive (like a motor), but who knows what
  yours is!

  2.4.  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
       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 cap.

  3.  Software

  3.1.  Software

  You will have to build an executable that will work like this:

    Get permission to use I/O address space, by calling kernel, with
     the command 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 a 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!

  3.2.  Device driver

  Just read kernel hacker's guide, implement a device driver (it could
  even be user space I think).  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 permission 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, so that smart
  coffee-machines could produce an interrupt.

  Do it as homework.

  3.3.  Connecting with the Internet

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

  4.  Overdose symptoms




    tachycardia or cardiac arhythmia


    Hypersensibility to light

    Annoyance in respect with various audio stimuli

    gastrointestinal disturbance

  5.  Expansions

  These are our ideas:

    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.

  6.  References

    http://daisy.uwaterloo.ca/~alopez-o/caffaq.html This is most known
     Internet's Coffee-FAQ

    http://faculty.washington.edu/chudler/caff.html Caffeine and
     effects of on the Nervous System

    http://www.gardfoods.com/coffee/coffee.coffee.htm 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.

    http://www.faqs.org/rfcs/rfc2324.html RFC2324: Hyper Text Coffee
     Pot Control Protocol (HTCPCP/1.0)

    http://www.faqs.org/rfcs/rfc2325.html RFC2325: Definitions of
     Managed Objects for Drip-Type Heated Beverage Hardware Devices
     using SMIv2

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

    http://lonestar.texas.net/~andrew/f_pc_.htm A lot of circuits in
     ASCII. Some of them are for parallel port.

    http://shell.rmi.net/~hisys/parport.html Whatever you wanted to
     learn about a parallel port and didn't dare to ask.

    http://www.redhat.com:8080/HyperNews/get/khg.html How to write your
     own device drivers. Come on, go ahead!

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

     Devices_Connected_to_the_Internet/Coffee_Machines/ Coffee-machines
     on-line. Unfortunatelly, there are no tests.

    http://www.cs.su.oz.au/~bob/coffee.html This coffee-machine offers
     only cappuccino. It has to be upgraded.

    http://einstein.et.tudelft.nl/~janssen/ Hot coffee from




  7.  etc

  7.1.  preface

  This document was initially written as part of a small debate in the
  linux-greek-users list , whether linux can make coffee or not.  It has
  been an article in our beautiful online magazine about Linux called
  magaz.  Remember, that magaz is greek it will look like that to you.

  7.2.  Authorship and maintenance

  My name is Fotis Georgatos and I have also been in the past busy with
  the greek documentation and wwwpages maintainance.  I welcome
  submissions to this HOWTO, as long as you're not anxious about the

  I'm Annie Pinder and a coffee fan. I live in England. I made the
  language changes on this document.  I'm currently in the English
  equivalent of High School, in my final compulsory year.

  7.3.  Copyrights

  The casual copyright with everything you get with linux...  To find
  it, you'll have to read all of HOWTOs and average out the most common.
  Otherwise, no, you cannot copy it.

  7.4.  Credits

    Ethiopia: Identified as the originating country of coffee.  As many
     people corrected, coffee did not originally come from America nor
     was brought by Christofer Colombus. It was popular in the Middle
     East long before America was discovered. Still, we can remember
     Cristobal Colon, as the person who brought tobacco and chocolate in

    Kostas Lialiambis is the one who dared saying that he can't make
     coffee with his Linux box.

    Panagiotis Vrionis, Yannakopoulos Haralambos, for giving me
     interesting and humorous notes.

    NUMEROUS people on the internet with additions and remarks.

: Sergey Guriev
, , webmaster@ja.fatal.ru