Hi, I have designed a watch using 3 counter stages with D flip flops. I want to eventually build this thing in real life. My question is about 7 segment displays, or really the decoders/drivers for them.

The decoders we use for seven seg displays cause the displays to show 0-F in hex when 0000-1111 are applied to it. Now since I am making a watch I want something a little different.

I have 6 D flip flop outputs which represent seconds, and 6 more which represent minutes. We won't talk about hours for now, I will deal with that later.

So the 7 seg display decoders have to take in a 6 bit binary value and show 0-60, while ignoring 61-63. Obviously you need two 7 seg displays for this, and each one must behave differently. One of them will show 0-6, and the other 0-9. So thats probably two decoders right there, one for each. The minutes portion is exactly the same.

Now its very easy to design a decoder that does this myself, but the amount of wires and gates necessary would be crazy. My question is, are there already such decoders for 7 seg displays out there that I can buy?

Thank you

 

Gonna be a really large watch. To shrink it use a microcontroller.

 

I want it to be large. Well it will be the size of a radio alarm clock.

What I'm trying to do is use only hardware. No software. I'm going old school. What I love about my design is that I understand how it works down to the cmos transistors. You can't beat that feeling. I wanna build something and be able to say, I understand how it works 150%.

 

Gonna be a really large watch. To shrink it use a microcontroller.

That's far too easy! count_volta wants the challenge, eh?

Perhaps he can have a digital watch with the huge LED displays on the wall.

Austin

 

Texas Instruments used to make the TIL311. It was a hex LED display with the logic built in.
Jameco actually has some: http://www.jameco.com/webapp/wcs/st...storeId=10001&catalogId=10001&productId=32951
At $20/ea, that's going to be a pricey watch.

Take a look at Maxim's ICM7212:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1675

 

You know what I decided. I will leave it a binary watch.

Only a real EE has a binary watch on his desk. It will also help me remember my binary. I already memorized 0-15, but anything higher and I have to look it up, or convert.

So it will display the time using LED's, and I will have little captions underneath that say minutes, seconds, hours.

Once I'm done I will post it in the projects forum and show a little video of it. This will probably be in the summer, as I am busy with coursework right now. This is just for fun. Thanks for the help guys.

Also, thanks Maxim's ICM7212 looks interesting and might be useful for other things I will do.

P.S. that brings up another question, are there TTL or other chips that have 6 D flip flops? All I have is 7474, and they are dual.

Answered my own question. The 74F174 chip.

 

I would not even put the hours, minutes and seconds caption on it.
Any bit-twiddler (programmer/analyst) or other person familiar with digital electronics should recognize what it is within a few moments, and be able to read it, too.

Why not design the clock so that you can switch between BCD and HEX display modes?

 

I want it to be large. Well it will be the size of a radio alarm clock.

I want to see a picture of that baby on your wrist!


You will be the envy of nerds everywhere!

 

I want to see a picture of that baby on your wrist!


You will be the envy of nerds everywhere!

You very well may. We live in the same city.