LPT interface with 8 Seven Segment Display...

[hassaan_july]

I Want to interface 7segment display with Assembly Language using parallel port...

The problem is Parallel port has 8 outputs and I want to connect 8 Seven segment display....how should I Do it...?

if using Multiplexer IC...then which will do my work Perfectly..?

 

[zuisti]

If you have 8 free output pin on your Parallel port, the only one possible way is the multiplexing:

1.
Use a 3to8 decoder IC like 74hc138 to choose one of the 8 display at a time
-- > 4 output pins (address A, B, C and inhibit).
2.
Use a serial-parallel converter IC to send the segment datas (I recommend the HC595)
-- > 3 output pins (clock, data, store).
4.
Use the aboves in a fast program cycle to get a continous display ...

Good luck.

 

[hassaan_july]

If you have 8 free output pin on your Parallel port, the only one possible way is the multiplexing:

1.
Use a 3to8 decoder IC like 74hc138 to choose one of the 8 display at a time
-- > 4 output pins (address A, B, C and inhibit).
2.
Use a serial-parallel converter IC to send the segment datas (I recommend the HC595)
-- > 3 output pins (clock, data, store).
4.
Use the aboves in a fast program cycle to get a continous display ...

Good luck.

if i use 3 to 8 decider i will only be able to use 2 seven segment displays.......

 

[zuisti]

"if i use 3 to 8 decider i will only be able to use 2 seven segment displays....... "
No, use the 8 decoder outputs to drive the commons of the 8 displays (of course via a PNP transistor, if you have common anode displays). One decoder output --- one display ...

 

[kak111]

Standard parallel port has 12 output pins and 5 input pins..................................

**broken link removed**

Parallel port output

**broken link removed**

.....Here is the steps to write your first parallel port interfacing application in VC++.
**broken link removed**

Parallel port - Wikipedia, the free encyclopedia

Regards KAK