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how to use the parallel port to control 9 or more device

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pcf8574p output register

how to use the parallel port to control 9 or more device indepedently....

help i'm thingking about this device to save electricy by using a controller (parallel port). the problem is i can only control 8 device at a time...

what i'm trying to do is to control 9 or more device independenty using he parallel port....

pls help me how....

any sugestion will be appriciated...

thanks..
 

hi
u can use multiplexer and tristate buffer for control your devices
 
With 8 data lines, 255 devices can be controlled (255 lines) by multiplexing the lines as 2^8.

from 00 to FF you can control.

..
 

To control several dvices via the parallel port don't use multplexers and/or buffers, as they work "momentary" .. you need latches ..
One option is to employ 8255 PPI ..
Here is an example:
"24-bit parallel port interface with 8255"
https://jap.hu/electronic/c64pio.html
Google for more ..

Regards,
IanP
 

You can use the parallel port's 8 data bits plus one of its control bits to give you 9 bits. General info here:
**broken link removed**

If you don't need high speed, another approach is to use a shift register such as 74HCT594. It provides eight outputs, and includes an output register. You can easily chain multiple devices, all controlled by a few wires. Here's a data sheet:
http://www.standardics.nxp.com/products/hc/pdf/74hc594.74hct594.pdf
 

Here is one of my designs a schematic of four 8-bit ports interfaced to the parallel port
86_1165665144.JPG
 

spy h / spy i is a single wire but can control n number of devices.
 

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