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!
For a long time, humanity was wondering how could a computer
People need coffee wake up and stay awake
in front of the computer for a long time.
Everyone knows that coding is better at night...
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
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.
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...
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.
This is a difficult one, read coffee-faq (see references)
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.
(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. Thatīs it.
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
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.
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 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
The simplest circuit that one can build is:
Relay /^\ Diode 1N4002
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 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...
If you only want a simple circuit, you can use Motorola's
triac driver MOC301, 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!
| 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
You should change resistors accordingly for 220V.
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.
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!
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.
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.
If you have implemented the C program (see above),
you just have to write a simple CGI script to turn ON and OFF
You should write some nice webpages, explaining how to make coffee,
and put them on an apache web server...
- tachycardia or cardiac arhythmia
- Hypersensibility to light
- Annoyance in respect with various audio stimuli
- gastrointestinal disturbance
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 hit.
- 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
- In the near future we will implement SNMP features.
- Serial coffee-machine at 115Kbps.
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
Remember, that magaz is greek it will look like that to you.
My name is
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 changes.
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.
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.
- 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 Europe.
- 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.