On the first day, I created the Parino card. The Parino card is a nice and affordable way to add control to any PC that has a (spare) parallel printer port. There are drivers and source code examples for DOS and Linux and the card is so simple and well documented that anyone can make software for every other computer in existence.
On the second day (12 years later) I got some doubt. Control applications are not very popular anymore. Still, the Parino card was nice for learning to program. Disadvantage: the relais are not really necessary, but they do make the card unattractive due to the high power consumption, the noise and their high price. So it was back to the drawing board and create a card that is
Above you see the circuit drawing for Parilux version 1. It has:
Bill of materials
Here is the BOM (Bill Of Materials) for the Parilux1 device. The table speaks for itself.
|Part||Description||Amount||Price €||Total €|
|ULN 2003A||Sevenfold high current open collector buffer||2||0.20||0.40|
|74HC257||Quad 2 to 1 multiplexer||1||0.25||0.25|
|LM 317||1.5 A adjustable voltage regulator||1||0.25||0.25|
|ICTE5||Transzorb 5 Volt power supply protector||1||0.50||0.50|
|Fuse||PolyFuse self resetting chemical fuse, 750 mA||1||0.50||0.50|
|Rectifier||Round rectifier bridge 1.5 A||1||0.20||0.20|
|Caps||WIMA capacitors 100 nF||3||0.15||0.45|
|Caps||Electrolytical capacitor 1000 uF||1||0.30||0.30|
|Resistors||Resistors in two shapes||12||0.02||0.25|
|Pot||Potentiometer, 25 turn, 1k||1||0.55||0.55|
|LED||3 mm LED's bicolour||4||0.12||0.50|
|DB25||SubD connector, 25 pin, male||1||0.30||0.30|
|Clamps||Wire clamp connectors, lift-type, 2 pins||2||0.30||0.60|
|Clamps||Wire clamp connectors, lift-type, 3 pins||1||0.45||0.45|
|Clamps||Wire clamp connectors, lift-type, 4 pins||2||0.55||1.10|
|Board||Printed circuit board||1||4.50||4.50|
|Total for the hardware||€ 11.00|
€23 for a versatile programmer's tool is downright cheap.
Applications of Parilux 1
Now we may have a nice circuit, but what can we do with it? My favorite answer for this kind of question is:
the applications are only limited by your own imagination. Let's first summarize what the card has onboard:
Parilux 1 has 7 useful outputs, all of which are fully buffered. They pose no load to the computer chips.
The ULN buffer is simple and sufficient. It has internal pull down resistors, so it's outputs are in a
solid OFF state when the computer is powered down. The outputs will withstand voltages upto 50 Volts.
Four of the outputs are equipped with LED's for creating light effects.
The other three outputs are fitted with 4k7 pull up resistors to create an open collector bus structure (like I2C). This is a very powerful bus however since each output can sink close to half an Ampere.
One of the five inputs is used for the easy part of the autodetect circuit. It is hardwired to one of the
'extra' outputs that live on address LPTbase+2.
The other four inputs are connected to the outputs of an HC257 multiplexer. One of the multiplexers is wired to +5V and GND and acts as the other half of the autodetect circuitry. The other three multiplexers transform 6 inputs to two groups of three inputs. All in all this gives us a powerful autodetect system plus 6 fully protected inputs.
The six actual inputs are buffered by a second ULN 2003. Two ULN inputs are wired together to form a wired AND gate. The other five inputs are ULN buffered with controlled inputs due to the internal pull down resistors. I could have choses HC541 drivers, but these would require external pull down resistors and protection circuitry to protect the device against overvoltages. A ULN does not need that. The inputs are guaranteed to withstand 30 Volts.
Parilux has its own power supply on board. It needs a 7.5 Volts AC or 9 Volts DC input. The on board
regulator will generate 5 Volts out of it. But you may change the output voltage of the LM317 by adjusting
the trim potmeter. Although this may harm the host computer.
I might also install an LM 1086 low dropout regulator so that the circuit can be run off a 7 Volt DC supply (6 NiCd's in series).
Still, the Parilux power supply will easily power the parilux and most of the add on circuitry. To further protect the Parilux, it is equipped with an ICTE5 TransZorb which will defend the power lines with its own life.
Parilux is equipped with a three fold auto dectection circuit. First of all, pins 14 and 15 are bonded
together. The software can put a value on the AUTOFEED output (pin 14) and check what level is available on
the 'ERROR' port (pin 15). This will already give a good indication of the presence of SOMETHING on the LPT
The multiplexer will also toggle one of the inputs between GND and +5V when bit 7 of the base poret is toggled. The combination of the two will give a 100% sure result of the presence of a Parilux device.
The LED's are for visual feedback. Newbie programmers just need this kind of feedback to see if their
actions pay off. But also seasoned programmers like the option to toggle a LED once in a while. It shows
the state of the software. It is the second step in programming, right after writing "Hello world".
You could also create an error code out of the four LED's. Or a heartbeat.
As you can see, There is a multitude of features. All of which are available to each and everyone. Some of the possible applications:
The circuit board
On the right you see the routed board. That is: these are the signal lines. Power and ground have been routed
seperately. Ground fills the spaces on the solder side of the board and the +5V supply fills the entire
topside of the board.
If you want to find out the nitty gritty, just order a PCB and you're home free.
The board has been designed and routed with Eagle. The PCB's were made at a professional PCB house based on the files produced with eagle. Some features of the board:
Why the fuse?
Yeah: why the fuse? I'll tell you why the fuse. It's there to protect your system from connection errors.
Remember, this is a realtime project. You connect your precious computer to the harsh environment in which WE
live. In this world, cars are not BONDED to the streets in the same sense as bits are bonded to an address
space. No, in OUR (human) world, safety cannot be bought. It must be enforced. At a cost.
We're about to connect the well guarded world of Linux to the chaos of reality. In this reality, which we learned to survive, anything that CAN happen, sooner or later WILL happen (Murphy's law). And we need to be prepared for that.
In web-publishing there is a rule: Only trust the server! In other words: users and clients are liable to misbehave. Same here: only trust the safety mechanisms you built in yourself.
Sooner or later someone will connect a GND connection to the +5 Volt power out of Parilux 1. The fuse (a chemical fuse, see below) will heat up at a rate defined by the current that flows. When hot, it immediately blocks the connection and it will remain like that until the voltage has been removed for 10 seconds at least. So the fuse protects us against short circuits.
The LM317 has internal short circuit protections as well, but I don't want to rely on that. If, for some reason, the LM317 is not on the board, there still must be some kind of protection. So this circuitry was added.
But what happens when someone connects a voltage hgigher than 5 Volts to our power out terminal? If that happens, the TransZorb kicks in and creates a genuine short circuit to Ground within nanoseconds. Within milliseconds the chemical fuse kicks in and creates a blocking condition on the Parilux card.
If the secondary power supply is well designed, it's own circuit breaker will kick in as well, but that is not really necessary. All in all, that means four safeguards (one external, one intrinsic and two explicit).
Getting a Parilux 1 board is easy. Just take a piece of VEROboard, the circuit drawing above and your junkbox. Within a day you have wired up your version of the Parilux 1 circuit. It will perform the same as the version I have, but it will not look as nice.
If you want a nice version of the Pariulx 1, you can buy one from me. Above I published the Bill Of Materials. The grand total of the parts is €11. That was my price and that's also your price for the parts. The price you pay lacks two factors: engineering costs and shipping charges.
I think € 12 is a reasonable charge for my efforts. I designed the board and took the risk of having made
a series of double sided PCB's which are now stacked up against the walls of my dungeon. This brings the grand
total to €23 for one PCB.
I set the shipping charges to €3 worldwide priority airmail. So if you want to collect one in Tilburg, NL: come and get one for €23. If that's too far away, have one or more sent to you for €23 plus €4 for shipping.
If you buy from http://www.reichelt.de then you may just include this list into your order.
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Page created 22 June 2007,