Parallel Port... again! - Electronic Circuits Projects Diagrams Free

Menticol · 23rd April 2008, 10:01 PM

Hi everyone!

I know it's already a thread about PP, but I'm having different troubles. I have made the newbie arrangement, diode, transistor, relay, load, and It's freaking me out:

Please:

1. Why does the PP fire random signals during system startup? There is some way to prevent that? (instead of disconnecting the port, ofcourse)

2. Can I receive signals through parallel port? According to almighty google yes, but it talks about complex circuits, I just want to know the state of a microswitch in my door

3. Why, if more than three "pins" are ON (I mean, firing 5V), the program goes lazy and cease to respond until I turn them off? Is this a programmer fault, or actually the PP has a limit of maximum "pins" active?

Thank you so much in advance!! My DIY proud is on the floor, and I don't want to switch to serial port yet

blueroomelectronics · 23rd April 2008, 10:08 PM

Your printer port was designed for a printer. Your OS is probably looking for a plug and play printer while its booting.

Menticol · 23rd April 2008, 10:13 PM

Quote:

Originally Posted by blueroomelectronics

Your printer port was designed for a printer. Your OS is probably looking for a plug and play printer while its booting.

Thank you for answering, by the way how could I make a circuit for filtering the signals, i.e. don't leting pass pulses of < 3 second of duration from the Parallel Port? (I know my lights will delay 3 seconds turning on, but is preferable)

ericgibbs · 24th April 2008, 08:03 AM

Quote:

Originally Posted by Menticol

Hi everyone!
1. Why does the PP fire random signals during system startup? There is some way to prevent that? (instead of disconnecting the port, ofcourse)
Trigger a monostable from a high going P378 pin, use the end of the mono period to set a latch, the output of the latch provides an enable signal to AND gates driving your output circuits.

2. Can I receive signals through parallel port? According to almighty google yes, but it talks about complex circuits, I just want to know the state of a microswitch in my door
Yes

3. Why, if more than three "pins" are ON (I mean, firing 5V), the program goes lazy and cease to respond until I turn them off? Is this a programmer fault, or actually the PP has a limit of maximum "pins" active?
No the Port can drive ALL the output pins High at the same time, unless your port driver is faulty.
Thank you so much in advance!! My DIY proud is on the floor, and I don't want to switch to serial port yet

hi,
Down load this zip and unpack it, place the two DLL's in the Windows/System folder also get from the web the VB5 runtime files. [free]
Look thru the pics and text for a port description.

Run the parport.exe to test and exercise the parallel port.

Its recommended that you use 74LS06 or LS07 buffers between the port and the OSWD.

Do you follow OK.

Menticol · 28th April 2008, 01:32 AM

Its Perfect!!! Thank you so much! Works great, and much more stable than the program I got. I just have 4 questions, If you have time

EDIT - I did some research (try and burn) and answered 2 answers - hope someone building the parallel port project could find them useful

1. What is a pull up resistor? Something like a ghost load? (The pins have internal pull up resistors)

unknown

2. According to the table, some pins have and active low signal, and others are inverted. What does that mean?

here is the answer
http://www.codeproject.com/KB/cs/csp...&select=974134

3. There are 8 "IN" on the port. So, if I want to check the state (i.e.) a microswitch in the window, should I connect any of those pins in series with the microswitch, and then (I guess) any ground?

10 /Ack In
11 /Busy In
12 Paper In
13 Select In
14 /Auto In/Out
15 /Error In
16 Initialise In/Out
17 /Select Prn In/Out

yes! that's the way it works. Refer to the above link for more info

4. Why is necessary to get the buffer? Is not enough to simply connect the port through a diode, and a transistor, to drive the relay?

unknown

Thank you again!

ericgibbs · 28th April 2008, 07:59 AM

Quote:

Originally Posted by Menticol

Its Perfect!!! Thank you so much! Works great, and much more stable than the program I got. I just have 4 questions, If you have time

EDIT - I did some research (try and burn) and answered 2 answers - hope someone building the parallel port project could find them useful

1. What is a pull up resistor? Something like a ghost load? (The pins have internal pull up resistors)
A pull up resistor is required in cases where the driver ic output pin is open collector, it has not got an internal resistor to Vss, a o/c pullup is about 220R thru 1K0 depending upon the application
Also pull up resistors are used on inputs to ic's in order to pull them to a 'good' logic high, about Vss, an input pullup can be typically from 1K0 thru 10K

In some cases the circuit may require a pull down resistor.

unknown

2. According to the table, some pins have and active low signal, and others are inverted. What does that mean?

here is the answer
http://www.codeproject.com/KB/cs/csp...&select=974134

3. There are 8 "IN" on the port. So, if I want to check the state (i.e.) a microswitch in the window, should I connect any of those pins in series with the microswitch, and then (I guess) any ground?

10 /Ack In
11 /Busy In
12 Paper In
13 Select In
14 /Auto In/Out
15 /Error In
16 Initialise In/Out
17 /Select Prn In/Out

yes! that's the way it works. Refer to the above link for more info

4. Why is necessary to get the buffer? Is not enough to simply connect the port through a diode, and a transistor, to drive the relay?
The PC port drive capability vary from one PC to another, some can supply 12mA and others 20mA at about +3.5V
This is often not enough to drive an external input, so a transistor amplifier is used to supply a higher current to the external load, relay etc.
unknown

Thank you again!

hi,
To keep things simple, I would suggest initially you use the 'IN's' port pins, the IN/OUT pins require o/c drivers.

Ask if you require mored detail.?

Feel free to cut/paste and use my VB5 source code anyway you wish.

Menticol · 20th June 2008, 05:06 AM

Sorry by bringing this old topic again, reciclyng is better than creating a new one.
The circuit is working great (thank you again Eric!), and now it's time to go further on the "PC Controlled Room".

Please:

1) Can the parallel port be interfaced to drive more than 8 devices?

2) I'm trying to measure room's temperature, and if higher than desired, turning on a fan. Offcourse, showing room temp. on PC screen would be great.

The existing solutions involves an LM35, comparator and a relay (No PC required), and a LM35's R232 interface to PC.

I would like to keep using the parallel, before buying adapters or older PC

My newbye knowedge states this:

The LM35 add +10 mV for each °C
If using a analog to digital converter...
Can this "mV value" be turned into binary, and then transmitted through any input line of the parallel? (Then VB makes the binary to base 10 conversion, and voilá!)

3) If you know about a good one, what R232 tutorial would you recommend for my application? (Plan B, If parallel port fails)

Thank you in advance!

Mikebits · 20th June 2008, 05:58 AM

Quote:

1) Can the parallel port be interfaced to drive more than 8 devices?

You only need 3 pins to address 8 devices. 0-7 or 000- 111. Use a address decode chip like the 74xx138, and use a 4th pin as an enable.

ericgibbs · 20th June 2008, 07:49 AM

Quote:

Originally Posted by Menticol

Sorry by bringing this old topic again, reciclyng is better than creating a new one.
The circuit is working great (thank you again Eric!), and now it's time to go further on the "PC Controlled Room".

Please:

1) Can the parallel port be interfaced to drive more than 8 devices?
Yes, Some posters are using 100 devices.!

2) I'm trying to measure room's temperature, and if higher than desired, turning on a fan. Offcourse, showing room temp. on PC screen would be great.
LM35 into a MCP3320, thats a dual 12bit ADC, connected to the Paraport.

The existing solutions involves an LM35, comparator and a relay (No PC required), and a LM35's R232 interface to PC.

I would like to keep using the parallel, before buying adapters or older PC

My newbye knowedge states this:

The LM35 add +10 mV for each °C
If using a analog to digital converter...
Can this "mV value" be turned into binary, and then transmitted through any input line of the parallel? (Then VB makes the binary to base 10 conversion, and voilá!)
YES.
3) If you know about a good one, what R232 tutorial would you recommend for my application? (Plan B, If parallel port fails)
The PP port just fine for all you are doing.

Thank you in advance!

hi Menticol,

Pleased to hear its working.

If you use Visual Basic, I could post the VB basic code for the LM35 and MCP3302 ADC.
Its rough and ready but it works for my projects.
You could modify to suit your application.

I use my VB programs in a similar way to project boards, I cut and paste my code, depending upon what I am measuring..

EDIT: attached screen shot.

ericgibbs · 20th June 2008, 01:13 PM

hi,
Correcting a typo in my last post. Unable to edit the post.!!

MCP3320 should read MCP3202

Menticol · 20th June 2008, 05:39 PM

Quote:

Originally Posted by Mikebits

You only need 3 pins to address 8 devices. 0-7 or 000- 111. Use a address decode chip like the 74xx138, and use a 4th pin as an enable.

Following that, I have found this schematic, clearer as water

My only question is, does the 74LS139 mantain its logical state even if the A B C D settings are changed? or do I need a flip flop circuit or something like that for each pin?

Quote:

Originally Posted by ericgibbs

EDIT: attached screen shot

Graph included, very nice!! Im looking for MCP3202 datasheet right now

ericgibbs · 20th June 2008, 06:12 PM

hi

The 74LS139 does not retain its output state, when the input address is changed.
Look at the HEF 4514 and HEF4515 for latched inputs and the HEF4043 and HEF4044 for latches.

Mikebits · 20th June 2008, 11:02 PM

Yes your right, the 138 is not latched. Thanks for pointing that out. Another part that would work is the 74HC237. It is the same as the 138 but with latches.

mneary · 20th June 2008, 11:33 PM

I've seen both 138 and 139 mentioned. Be sure you know the difference before you buy or hook up.

Menticol · 21st June 2008, 02:20 AM

Latched inputs

Just to make sure, the HEF4515 says "with input latches". Does that mean that even if the input is changed, the state of my previously actioned output pins will be mantained?

My english is not very good, so here's an imaginary example:

A = high
B = high
C=low

result: O13 low

then:

A = low
B = low
C= high

result: O15 low and O13 KEEPS low, as previously

To get O13 high, put A=high B = high C= low again

Latches

I have checked the latches IC's, but they include a "ON" pin and a RESET pin. So I need 2 transistors, to actuate the ON and RESET for each pin. Is that correct? I find it too complex (30 transistors!!)

Thank you!!! And sorry if I'm shooting questions like a machine gun

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Title	Starter	Forum	Replies	Latest
Parallel port control port: is it Write Only or Read/Write	elexhobby	Electronic Projects Design/Ideas/Reviews	6	23rd December 2008 11:18 AM
Parallel Port & Microcontroller	Omar.M	General Electronics Chat	10	14th August 2007 10:31 AM
Need help badly on Inchworm and MPLAB	thushy	Micro Controllers	14	11th March 2007 07:05 PM
I need: Parallel Port.. examples and applications..	sonaiko	General Electronics Chat	8	28th October 2006 02:44 PM
Multiple devices controlled at once on one parallel port	Kerri Ann	Electronic Projects Design/Ideas/Reviews	0	18th February 2005 11:52 AM

23rd April 2008, 10:01 PM	(permalink)
Menticol	Parallel Port... again! Hi everyone! I know it's already a thread about PP, but I'm having different troubles. I have made the newbie arrangement, diode, transistor, relay, load, and It's freaking me out: Please: 1. Why does the PP fire random signals during system startup? There is some way to prevent that? (instead of disconnecting the port, ofcourse) 2. Can I receive signals through parallel port? According to almighty google yes, but it talks about complex circuits, I just want to know the state of a microswitch in my door 3. Why, if more than three "pins" are ON (I mean, firing 5V), the program goes lazy and cease to respond until I turn them off? Is this a programmer fault, or actually the PP has a limit of maximum "pins" active? Thank you so much in advance!! My DIY proud is on the floor, and I don't want to switch to serial port yet Last edited by Menticol; 23rd April 2008 at 10:04 PM.

23rd April 2008, 10:08 PM	(permalink)
blueroomelectronics	Your printer port was designed for a printer. Your OS is probably looking for a plug and play printer while its booting. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

20th June 2008, 05:06 AM	(permalink)
Menticol	Sorry by bringing this old topic again, reciclyng is better than creating a new one. The circuit is working great (thank you again Eric!), and now it's time to go further on the "PC Controlled Room". Please: 1) Can the parallel port be interfaced to drive more than 8 devices? 2) I'm trying to measure room's temperature, and if higher than desired, turning on a fan. Offcourse, showing room temp. on PC screen would be great. The existing solutions involves an LM35, comparator and a relay (No PC required), and a LM35's R232 interface to PC. I would like to keep using the parallel, before buying adapters or older PC My newbye knowedge states this: The LM35 add +10 mV for each °C If using a analog to digital converter... Can this "mV value" be turned into binary, and then transmitted through any input line of the parallel? (Then VB makes the binary to base 10 conversion, and voilá!) 3) If you know about a good one, what R232 tutorial would you recommend for my application? (Plan B, If parallel port fails) Thank you in advance! __________________ La Rotta Last edited by Menticol; 20th June 2008 at 05:08 AM.

20th June 2008, 01:13 PM	(permalink)
ericgibbs	hi, Correcting a typo in my last post. Unable to edit the post.!! MCP3320 should read MCP3202 __________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/ Last edited by ericgibbs; 20th June 2008 at 01:14 PM.

20th June 2008, 06:12 PM	(permalink)
ericgibbs	hi The 74LS139 does not retain its output state, when the input address is changed. Look at the HEF 4514 and HEF4515 for latched inputs and the HEF4043 and HEF4044 for latches. __________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/

20th June 2008, 11:02 PM	(permalink)
Mikebits	Yes your right, the 138 is not latched. Thanks for pointing that out. Another part that would work is the 74HC237. It is the same as the 138 but with latches.

20th June 2008, 11:33 PM	(permalink)
mneary	I've seen both 138 and 139 mentioned. Be sure you know the difference before you buy or hook up.

21st June 2008, 02:20 AM	(permalink)
Menticol	Latched inputs Just to make sure, the HEF4515 says "with input latches". Does that mean that even if the input is changed, the state of my previously actioned output pins will be mantained? My english is not very good, so here's an imaginary example: A = high B = high C=low result: O13 low then: A = low B = low C= high result: O15 low and O13 KEEPS low, as previously To get O13 high, put A=high B = high C= low again Latches I have checked the latches IC's, but they include a "ON" pin and a RESET pin. So I need 2 transistors, to actuate the ON and RESET for each pin. Is that correct? I find it too complex (30 transistors!!) Thank you!!! And sorry if I'm shooting questions like a machine gun __________________ La Rotta