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Joined: Fri May 05, 2017 7:39 pm
Posts: 22
actionfingers wrote:
I know it might be a little soon to be asking questions, but I'm stumped. Hoping someone can help me out.

I've been reading Understanding Digital Electronics. At the top of page 1-9, it gives an example where if scan line 9 is on and segment lines a,b,c,d,g,h are on, then the number 3 will be displayed. If scan line 9 is being turned on, shouldn't segment lines a,b,c,d,f,g, and h be turned on displaying a "9?" I feel like I'm missing something or that I'm not totally grasping the material.

Thanks in advance for any guidance.

Welcome actionfingers!

The displayed numbers (or symbols!) depends on the turned-on segment lines, the position (where the symbol becomes visible) within a multiple digit display is selected by the scanlines. You should only activate one scanline at once.

The segment line for h is "optional" as you can add a dot/decimal point to all symbols if needed.

You can not only display numbers, some letters are easily recognized as well:

"A" requires a,b,c,e,f,g to be turned on, all others off.
"b" requires c,d,e,f,g to be turned on, all others off.
"C" requires a,d,e,f to be turned on, all others off.
"d" requires b,c,d,e,g to be turned on, all others off.
"E" requires a,d,e,f,g to be turned on, all others off.
"F" requires a,e,f,g to be turned on, all others off.

Some letters are really difficult - that's why there are 14- and 16-segment-displays as well ;-)
PDC54-11GWA-57682(1).pdf [249.88 KiB]
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Last edited by GaBuZoMeu on Thu Sep 06, 2018 11:16 am, edited 1 time in total.

Thu Sep 06, 2018 11:06 am

Joined: Wed Aug 29, 2018 11:07 am
Posts: 9
I appreciate all of the feedback! Thank you!

I believe I was just confused. I finally realized that it was basically just covering how a number gets sent to the display, not what button was pressed to get that number. That's why I kept asking myself why a '3' was being displayed when scan line 9 was energized. Because scan line 9 was energized, I just assumed that the '9' key was being pressed and that's not necessarily the case in this bit of text.

At least I think that's what had me confused. LOL

Thanks again!

Thu Sep 06, 2018 11:14 am

Joined: Sat Jun 16, 2018 2:51 am
Posts: 45
I've found these two resources very helpful as a starting point:
Their emphasis is on building a (simple) CPU if that's the route you want to take at some point.

Mon Mar 25, 2019 11:11 pm

Joined: Wed May 15, 2019 1:17 am
Posts: 21
I'll put in a shameless plug to my own set of beginner videos. Ben Eater's ones are more professional, though.

Crazy Small CPU Playlist: How Does a CPU Work?

Wed May 15, 2019 2:33 am
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