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Using 12 outputs of parallel port for multiplexing???

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as727

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I am designing a circuit which requires 96 outputs from the parallel port which is achieved through multiplexing, using the 8 data lines available on the port. Each of the 96 outputs will then be used to enable a latch. However, I also need an additional 3 lines of data into each of these latches, so I think I will need 11 outputs.

I read that the parallel port can be used in "output" mode to allow the control lines (pin 1, 14, 16, 17) to be used as data outputs- which would give me 12 data lines. Will this work as I am suggesting? Will I just need to address the data and control lines separately when programming?

Any help or info regarding this would be much appreciated
-Andy.
 
I am designing a circuit which requires 96 outputs from the parallel port which is achieved through multiplexing, using the 8 data lines available on the port. Each of the 96 outputs will then be used to enable a latch. However, I also need an additional 3 lines of data into each of these latches, so I think I will need 11 outputs.

I read that the parallel port can be used in "output" mode to allow the control lines (pin 1, 14, 16, 17) to be used as data outputs- which would give me 12 data lines. Will this work as I am suggesting? Will I just need to address the data and control lines separately when programming?

Any help or info regarding this would be much appreciated
-Andy.
hi,
The 4 line port is used to address a 4 to 16 decoder IC.
The 16 output pins of the decoder are used as Select lines for upto 16, 8bit latches for the 8 line port.
So you have the possibility of 8 * 16 = 128 external outputs

OK.?
 
>The 4 line port is used to address a 4 to 16 decoder IC.
so the control pins can be used as address lines, like the data pins can? (accounting for the pins being inverting)

Also, I understand the 128 outputs from 4 address + 8 data lines, but what I am looking for is 96 outputs from 5 address lines and 3 data lines, and then an additional 3 data lines to each latch enabled by each of the 96 outputs. So each of the 96 outputs needs 3 bits of data. I'm just not sure if this will work as I am describing.
 
>The 4 line port is used to address a 4 to 16 decoder IC.
so the control pins can be used as address lines, like the data pins can? (accounting for the pins being inverting)

Also, I understand the 128 outputs from 4 address + 8 data lines, but what I am looking for is 96 outputs from 5 address lines and 3 data lines, and then an additional 3 data lines to each latch enabled by each of the 96 outputs. So each of the 96 outputs needs 3 bits of data. I'm just not sure if this will work as I am describing.

hi,
Any chance you could post a simple block diagram so that I can be sure what you are looking for, its sounds possible.
 
In retrospect I probably should have drawn it up earlier- the best I can do is an MS paint diagram. BRB

**broken link removed**[/IMG]
 
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In retrospect I probably should have drawn it up earlier- the best I can do is an MS paint diagram. BRB

hi,
That will be OK.
Do you need any parallel port datasheet type information.?
 
There should end up being 32 4-bit latches enabling another 96 4-bit latches, to give 96, 3-bit outputs
 
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I am using parallel port first time. I have general idea of having 2 to 8 pins which can be used to send data to turn on and off.
First, I have application to have at least 32 to 64 pins to send data to make turn on or off transistor which acts as a switch. Please guide me how I can increase data lines. Please post circuit of it if anybody has idea of it.
Second, I have application to have at least 8 to 16 pins to receive data from circuit to check status which will be checked through program. Is it possible to make some of output pins to set as input along some output enabled?

Can I use 2-3 parallel ports ? If yes, where I can find addresses of each? I have USB to parallel port cables.

Thanks.,

I will be very helpful as I am doing final year project and I am stuck in it. I am having deadlines of 12 days.
 
Be aware, USB to parallel converters do not support many of the non-printer applications that the original parallel ports did. If your only choice is using USB to parallel converter you must first find out what it's actual capability is.

As for increasing the number of data lines, the easiest is to have different successive bytes do different things.
You might allocate the msb to be a byte type indicator.
Byte 0 (msb =0) is 7 bits of data that gets saved in a temporary latch
Byte 1 (msb =1) is the address where the previous data gets sent to.

This gives you 128 places that you can send 7 bits of data to. That can give you 896 individual 'pins'.
 
Be aware, USB to parallel converters do not support many of the non-printer applications that the original parallel ports did. If your only choice is using USB to parallel converter you must first find out what it's actual capability is.

As for increasing the number of data lines, the easiest is to have different successive bytes do different things.
You might allocate the msb to be a byte type indicator.
Byte 0 (msb =0) is 7 bits of data that gets saved in a temporary latch
Byte 1 (msb =1) is the address where the previous data gets sent to.

This gives you 128 places that you can send 7 bits of data to. That can give you 896 individual 'pins'.


You mean USB to parallel port may not support sending data (for non-printer application).

In case if I arrange parallel port through expansion card or attached with motherboard,
I understood what you are saying that I can control and expand pins by having circuit consists of latch.

But can you do me favor? Can you find circuit to do it? I don't have any idea of it.
I have general idea that through decoder and latch combination, I can expand pins of parallel port.
 
Don't use a parallel port, they are long since obsolete - have any relatively modern computers even had them?.

USB converters aren't a real parallel port, and unlikely to work for direct pin access (I've never managed to use one in that way - specifically for PIC programmers).

The way to go is to use a PIC (or other micro-controller) to do all the connections and interfacing, and a simple serial interface from the computer to control it (using a USB/Serial converter if required, as is likely on any modern machine).
 
Actually, I have application to control whole circuit via PC commands.
Is it possible with micro controller?

As far as I know, microcontroller has to be pre-programmed and then whole program works as per written program on micro controller.

Is there any way to control microcontroller which controls whole circuit and whole control is done through PC simultaneously?

Please suggest me suitable circuit to do it?
I just need 32 pins which work as output and 8 pins which work as input.

I only have USB ports. My PC doesn't have serial port or Parallel port.
 
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Google "usb digital I/O"
There are lots of off the shelf products that should work for you.
 
Actually, I have application to control whole circuit via PC commands.
Is it possible with micro controller?

As far as I know, microcontroller has to be pre-programmed and then whole program works as per written program on micro controller.

Obviously you have to program the microcontroller, but you simply write it for what it does to be controlled from the PC - this is how the PICKit2/3 etc. from MicroChip work - the PC simply tells the PIC what to do, and the PIC follows the commands.

This is also how the USB digital I/O mentioned by ChrisP58 work.

Is there any way to control microcontroller which controls whole circuit and whole control is done through PC simultaneously?

No idea what you mean by that?, the PC simply send instructions to the PIC, and the PIC carries out the operation.
 
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