Parallel port BUS system.. (Controling 20 lights on 1 port)?

Question

Basicly I have made a simple program that can send binary bits out on a parallel port and I made a tester to see which pins light up etc...

it's very simple.... basicly what I am getting out of this circuit is a binary representation of the bit I send down the line.. for isntance if I send a binary bit of 3 down the line LED1 and LED 2 comes on!.

What I would like to do is make several devices all on 1 parallel port and I would like them to respond to certain binary paterns

for instance 01011001 might mean light 1 on

just imagine a series of lights and I want to control let's say 20 lights from 1 parellel port.

if you have a way of doing this I would be very greatful if you could let me know. Are there any IC's or any type of unit I can buy which could activate on certain binary paterns (Addresses)?

Answer 1

hello there.
I do exactly what you are doing, all the time.
You do not state what language you are using.
I have a website that shows how to use an original PC
( no harddrive, no CD, no colour, no sound, no mouse, and even
no floppy with 16K of ram, etc.) to control the parallel port.
Please see
kidbots.com
You can EASILY control 4, 8-bit ouput chips, using the 4 CONTROL pins on the parallel port to turn off or on any 8 bit
buffer chip that has a pin to ENABLE or Disable the entire chip.
Then, you can use 4 x 8 = 32 devices.

If you want to JUST use the 8 bit DATA out pins, then you have to add some other chips to decode the information, for example
1000xxxx would be sent to turn on just one of the 8 bit buffer chips.
0100xxx would turn on the next of 4 chips, but note that the chip would only have 4 binary outputs,
0010 and 0001 would turn on the last two of four chips.

OR you could use the DATA out 01xxxxxx to turn on one 8 bit buffer, which would have 6 outputs useable,
and 10xxxxxx would turn on the next chip.

I wrote the basic program to be as SIMPLE as possible, since the website and the design is intended for 11 or 12 year old kids, so that the electronics have to be easily made and CHEAP so that kids can afford it. I use one pin out of DATA to simply control one device, BUT,
you can get into logic circuits that decode the BINARY and put out the DECIMAL equivalent on a HUGE number of chips and pinouts. I just never got into this, since I am trying to use old, thrown away computers as cheaply as possible, to quickly make an easy interface.
As you know,
00000001 is 1
00000010 is 2
00000100 is 4
etc. so that with 8 bits, you can control
2x2x2x2x2x2x2x2, or 256 individual devices -- however, getting an " EASY " chip interface to decode the binary, and HAND WIRE all the ciruits and chips, is NOT easy..
Using the 4 control pins to turn on or off the 4, 8-bit buffer chips, would be the simplest, easiest way to complete your task.
The 8 data pins would be wired to ALL 8 pin inputs of the 4 Buffer chips at the same time ( very easy to wire ).
Each of the 4 buffer chips would have 1 wire going to only 1 of the 4 CONTROL pins, and therefore, only ONE of the 4, 8-bit chips will turn ON at one time ( if you program only one of them to do so -- you could turn on 1 and 4, 1 and 3, 2 and 4, or 1 and 2 and 3 and 4 at the same time, as well, but the outputs would have the SAME pins on each chip output the values -- since they are wired identically )
Most devices that use LED's as displays, DO NOT have all the lights on at the same time -- take an ordinary LED red calculator display ( if you can find one ) and in a dark room, swing it at arm's length in front of you. You will see a row of flashing dots. This is because only one digit is on at any given time, and the flashes repeat constanly so that it APPEARS that all the lights are on. You could do the same using my scheme - you program fast enough to repeat the program so that although only one bulb or LED or light is on at one moment, the appearance would be one or any or all " ON " at the same time ( if you use fast, electronic switching -- relays would be too slow to cope with the illusion ) To have TOTAL control over 20 lights, individually, using transistors to turn on or off the relay coil current, you would have to use " binary 32 " as the smallest number or 2x2x2x2x2 or 5 binary digits. You would then have to have 20 outputs, and a decoder circuit to decode binary, to 20 Decimal ' OUTS ". ( throwing away or ignoring the unused outputs from 20 to 32 ).
There are a great many binary to Decimal converter chips, and wiring them to get sequencial outputs is tricky, if you don't work with the chips all the time, but there are many online diagrams that show how to chain these outputs...
You will have to do some reading, but there is a wealth of information out there !

ANSWERS.yahoo does not have any way to immediately attach a drawing, so that I can't show a quick wiring scheme...

I used BOTH the 74xxx series of old, TTL ( 5 volt only ) chips,
and the newer 40xxx series of chips ( 3 to 16 volts ) and many
74Cxxx chips which are an internal CMOS ( 40xxx) circuit that is adjusted to "look like" the old 74xxx TTL ( Transistor Transistor Logic ) ( CMOS is Complimentary Metal Oxide Silicon fabrication )
If you go onto the web, you can look at electronic suppliers near you ( I do not know where you are ) and look for CMOS pinouts, or TTL pinouts, or DIGITAL chips etc. and find the 8 bit buffer chips. Some are inverting ( 5 volts IN = 0 volts OUT ) and some just buffer ( 5 Volts IN = 5 Volts OUT ). (You want chips that have enable or dissable pins.) I use BOTH buff and Invert types,, since the parallel port already inverts half the signals in the first place, and my programming uses NON-Inverted outputs to make it easy for the kids. I deliberately invert the INVERTED outputs, so that 0 = 0 Volts, and 1 = +5 Volts, all the time. Otherwise, the programming is a mess. You can use INVERTER chips as well, or just use PNP or NPN transistors to invert a single pin. I have not put on the wiring on my website yet, since every single supplier of parts had been sold / tradded / or dropped the parts I use, and I cannot cross reference part numbers and price lists for kids to order, since I cannot find a single reliable supplier who " WANTS " to supply to kids...
Hope this information helps - if you have further information on your program, or what kind of hardware wiring you use or further question details, post them, and I will get back...

robin

Answer 2

LAMO!!!! dis is rel jones a lil humor is always good girl lol and yeh i like julien ah watchin mi lunch lil different now too jed

Answer 3

i have no clue on this subject but i may suggest trying to post it in electronics see if anyone there has an idea

anyway good luck sounds like fun

Answer 4

got absolutely no clue on how to help ya but i noticed no one even bothered to try and help so i might be in line for a best answer!!!