8bit Binary number to multiple 7Seg Displays

[Tony Stewart]

You might be able to use the truth table for a DM74184 which requires 3 chips that uses a ROM lookup for HEX to BCD

BobW, Shouldn't the truth table be for $00 to $ff input ( 8bit) and big Endian BCD out? ( 3 digits) or whatever for BCD to 7 seg digits?

 

[Mike0rr]

I have yet to deal with most of these techniques so I'm not sure what one would be the best option for me yet. I was really just hoping I would even get one solution, let alone multiple. I'll start looking into all of these options and see what turns out working best for me. I honestly like the old BCD to Binary chips you stack together but if I can't get a few on the cheap then it's, option exploring time. I really shouldn't pass on another learning chance anyways. The EPROM's sound really interesting and I think those are something I will look into regardless of using them in this calculator so I'm thinking that they may be my second option, but that's hard to say, being that I know very little about them; For now

I really appreciate all the help guys. I've been kind of nervous to ask questions some might deem too rudimentary to even glance at. I know you guys don't have to help out a random little guy like me but I will surely pay it forward when the opportunity presents itself. Keep helping out us beginner engineers. You help more than you know : )

 

[Tony Stewart]

3 bit BCD to OCT is easy
You are computing in HEX and converting to BCD
It was so costly to do in calculators and even Quad Core CPU's they do it in software because of the hardware prop delays are not fast enough to make it worth the cost of ARU speed core chips.

All calculators compute in BCD,, which gets back to my previous question. WHY HEX to BCD.

 

[Mike0rr]

I am using Binary because, this project started out very basic. I honestly just watched a video on how memory was stored and wanted to use it on something basic, like button presses to a calculator. Making a Calculator also enabled me to prototype through a game that I could get some "hands on" learning done, which for me is great (also free). Most of these Calculators had Binary switches for inputs though and I was not satisfied with that, especially when the inspiration to the project was saving a button press to a constant "on". It quickly spiraled into an awesome learning process though, much further than the original idea I wanted to explore and I'm very happy to have done so this away. The first Calculator I made (in game) only added to 15, (not using the carry out of the last adder) so I took the same principals of the small Calculator and expanded off of it.

Was this the best or even correct way to go about this? Maybe not, but that isn't the point. The point was to learn and honestly, I enjoy it even more if it was unorthodox. It may not be the most effective, cost efficient, fast or powerful way, but I this did myself. There was no step by step guild. I've needed help on a few topics but I have never asked for direct help (Where do I plug this in? What did I do wrong? Do this for me.). Only "how is this gone about"s. If I wanted to have this done with a micro controller, or some fancier chip I could also have just went down to the dollar store and picked up myself a Calculator there, or at least picked up some Calculating chips that had most of the work cut out for me already but I would have learned much less. My point here is that this was a project to learn basic information off of. Maybe it's not done like this anymore. Maybe it's outdated information that isn't so helpful today. Maybe I didn't follow the best path for executing this idea. But none of that matters. It sparked my interest in the subject, I've learned plenty of things that are still useful today and it has me thinking of other projects to do later on. You learn from the problems you encounter.

So if you are wondering "Why Binary and BCD?" to understand what parameters I could change to remedy the problems I am working under, there you go. But if you are asking why did I do this such an old school, or "dumb" way, I did it to learn.

 

[crutschow]

.....................
BobW, Shouldn't the truth table be for $00 to $ff input ( 8bit) and big Endian BCD out? ( 3 digits) or whatever for BCD to 7 seg digits?

I believe the truth table is for the ROM only, not the complete circuit he showed in Post #17.

 

[BobW]

You might be able to use the truth table for a DM74184 which requires 3 chips that uses a ROM lookup for HEX to BCD

BobW, Shouldn't the truth table be for $00 to $ff input ( 8bit) and big Endian BCD out? ( 3 digits) or whatever for BCD to 7 seg digits?

Eight bit input is unnecessary, because the least significant binary input bit has no effect on anything other than the least significant output bit. The most significant BCD digit only requires two bits because the only allowable values are 0, 1 and 2.

I believe the truth table is for the ROM only, not the complete circuit he showed in Post #17.

Correct, it's just for the ROM.

 

[mbarazeen]

Mikeorr it is interesting to know about your project with basic stuffs. Can you explain little bit about your calculator project too? Once i made a kind of calculator for my daughters school exhibition to multiply two numbers 12 x 12 max and displayed the values on a display. everything went in a box with about 30 ICs. I used counters with 500kHz clock.

 

[koolguy]

(Example: Decimal 52, is Binary 00110100).

Hello Mike,
52 in decimal , in binary should be 0b0010100100.
something like this

 

[Ian Rogers]

52 in decimal , in binary should be 0b0010100100.
something like this

Not even close Ritesh!!!!

0b0010100100 = 128 + 32 + 4 = 164..

0b00110100 = 32 + 16 + 4 = 52..

 

[Mike0rr]

Mikeorr it is interesting to know about your project with basic stuffs. Can you explain little bit about your calculator project too? Once i made a kind of calculator for my daughters school exhibition to multiply two numbers 12 x 12 max and displayed the values on a display. everything went in a box with about 30 ICs. I used counters with 500kHz clock.

Yeah, I plan to set up a little "how to" after I finish it but if the process for converting a number is so outdated and difficult I will have to do a bit more work to figure out how to make it easier to replicate. I think there is a lot of useful information in learning how to make it. I think it could be a great learning project : )

Hello Mike,
52 in decimal , in binary should be 0b0010100100.
something like this

I have no issue mentally converting the Binary. I was asking about getting my Binary output into a format a 7segment display could use.