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Altera_Forum
Honored Contributor I
1,943 Views

DE2 board, 7-segment display via schematic

I'm trying to create a simple circuit, using 4 switches (8-4-2-1) to drive digital logic, in order to light a single 7-segment LED. 

 

I've created the 4 input pins, wired them to inputs A,B,C, and D of a 7447 (BCD to 7-segment decoder), and wired the 7 outputs OA through OG) to output pins. I've tied the other 3 inputs (LTN, RBIN, BIN) to ground. I've assigned switches 0 through 3 to the inputs, and HEX0[*] to the outputs. However, when I compile, I get warnings that: 

 

Warning: Design contains 4 input pin(s) that do not drive logic 

Warning (15610): No output dependent on input pin "B" 

Warning (15610): No output dependent on input pin "C" 

Warning (15610): No output dependent on input pin "D" 

Warning (15610): No output dependent on input pin "A" 

 

Warning: Following 7 pins have nothing, GND, or VCC driving datain port -- changes to this connectivity may change fitting results 

Info: Pin OA has VCC driving its datain port 

Info: Pin OB has VCC driving its datain port 

Info: Pin OC has VCC driving its datain port 

Info: Pin OD has VCC driving its datain port 

Info: Pin OE has VCC driving its datain port 

Info: Pin OF has VCC driving its datain port 

Info: Pin OG has VCC driving its datain port 

 

Downloading to the DE2 board yields no results. The HEX0 (rightmost) 7 segment display is off, and no change in the input switches produces any change. It seems that the 7447 chip is not being utilized correctly... That the input pins are not connected to inputs on the 7447, and likewise for the outputs. 

 

I don't think I'm doing anything wrong with wiring or pin assignments; when I connect a switch directly to an LED, it works fine. If I put an inverter between them, that works fine. But the 7447 doesn't seem to work correctly. Any suggestions?
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4 Replies
Altera_Forum
Honored Contributor I
324 Views

Maybe could be usefull if you post some of the code that you've done, to help you.

Altera_Forum
Honored Contributor I
324 Views

As I said, I did the design via schematic. Here is a screenshot: 

 

http://farm4.static.flickr.com/3236/2887864395_823e7d95da.jpg  

 

The circuit on the top is what I'm trying to get working; the switch-inverter-LED on the bottom was just to verify that I hadn't missed something on the real circuit.
Altera_Forum
Honored Contributor I
324 Views

Try this: 

LTN = H 

RBIN = X 

BIN = H 

 

You've this: 

LTN = L 

RBIN = L 

BIN = L 

 

Then ignore the warnings.
Altera_Forum
Honored Contributor I
324 Views

That should do it, thanks. All the warnings threw me for a loop, when I should have been looking at the data sheet more closely.

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