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Need help with 7 seg display

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Member level 4
Mar 27, 2002
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My problem is hopefully simple.

In school we use M*lti*sim Edu ver.

the default 7 segment displays have 8 inputs.
1~7 goes to A~G. but there is an extra for COM.

the Pro has only 7 inputs! A~G no com.

In school we connect com to 5v and all good.
But Pro. If i just connect display to 74LS138 my display is reversed! what should be lit is not and what shouldn't is lit!

I was going to make my own display by modifying the default display but Pro won't let me.

I don't have much experience in making my own components so hopefully wiser members can teach me how to make my own components like a seven segment display with a comm input.

I ask so others with same problem can learn too.



Are you using Pro**teus sp6 ?

If so download attached LEDMPX.DLL. This model in sp6 has been proved to be faulty. Attached library works ok.

By the way, if you want to draw a multiplexer 7 seg leds, dont use at all 7SEG-DIGITAL. It's common cathode where the cathode is connected to ground in the model, so is not available to you. Again, don't use 7SEG-COM-ANODE and 7SEG-COM-CATHODE. They are mixed mode models (digital + analogue), so you will slow down simulation with bad flikering effects.

The only model you've to use are:

7SEG-MPX2-CA 2 mpx common anode
7SEG-MPX2-CC 2 mpx common cathode
7SEG-MPX4-CA 4 mpx common anode
7SEG-MPX4-CC 4 mpx common cathode
7SEG-MPX6-CA 6 mpx common anode
7SEG-MPX6-CC 6 mpx common cathode

As every COM is available, if you need for example 8 digit, common anode bank, you may use 7SEG-MPX6-CA and 7SEG-MPX2-CA. Please note the six above model make available the dot point also. (all real LED have a dot point pin available).

Further, go to this link:
**broken link removed**

and see for PROGRAMMABLE TIMER FROM 00:00 To 59:59. It is an application I drawn using multiplexed 7SEG LEDs. This application works nice in sp6 too, provided that you will replace the LEDMPX.DLL with the attached one.

Finally, search in the forum (use search function, bottom the page) for "proteus".
Many posts have been issued for this matter.

Hope this help you.


Uploaded file: **broken link removed**
Last edited by a moderator:

7seg-mpx6-ca 6 mpx common anode


Thank you for reply but,
I'm using M*lt*s*m Pr* ver.
If anyone can show how with M*lt*s*m Pr*. help will be appreciated.

Thank you WA

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