urgent help plz regarding 7 segement Display!

[cs200939]

hi.I have made a fibonacci series generator.now theres a last problem i am stuck at i.e ive used two 4 bit adders to add the two 8 bit numbers.i mean one adder adds the first 4 bits and the other adds the next for bits with carry coming in from the first adder.now the problem is that i want to display this on 7 segment displays.so far ive worked with only one 7 segmet display to display numbers between 0 to 9.ive never used two segments to display 0 to 99 nos but i want to display the series till 99 so how can i connect two 7 segement displays to make this happen?e.g if i add 00000001(1) to 01000000(64), the answer is 01000001 which is 65.. now how can i display 65 on two 7 segment displays?6 on one display and 5 on other display and consequently all numbers between 0 and 99

 

[birdman0_o]

It is easy to count from 0-99 and display that. Taking 8 bits and displaying them using 4 bit decoders is rather hard! Unless you can find a chip that takes 8 bits as input, you are entering the digital domain :S which is not what you want from what I read.

 

[cs200939]

so what should i do?..i cant use microcontrollers.thats for sure

 

[birdman0_o]

Hey! Found this chip showing this on the DS
https://www.electro-tech-online.com/custompdfs/2010/12/DM74185.pdf

 

[Hasnatsaeed]

awesome..it really works rite?

 

[birdman0_o]

I would hope so, I checked my drawers for the Bin- BCD but could not find any
Would you like me to test it for you?

 

[Hasnatsaeed]

plz that'l highly appreciated...this is the last glitch in my project..everything is done except for this..my project wont be accepted until i display that 8 bit series on 7 segment displays!

 

[birdman0_o]

Do you have 3 Binary to BCD decoders?

 

[Hasnatsaeed]

i have 4 binary to BCD decoder..thats 74LS47..i can make it 3 binary to bcd

 

[Hasnatsaeed]

i dont exactly remember this but my teacher told me that there are some ICs which break an 8 bit number into groups of 4 and decode them separtely like eg the first ic decodes the tenths place and the second decodes the units place and hence you can display them separately and something like that..hes out of town so thats another "thats so wrong" thing for me

 

[birdman0_o]

I meant do you have 3 of the chips. Why not try to make whats in the schematic I posted?

 

[Hasnatsaeed]

oh sorry..i have to make some calls before i can answer this..ill b back soon

 

[Hasnatsaeed]

ok i ve contacted some retailers and they have told me that they can get them after a week...so plz tell me now how should i make this 8 bit to 7 segment decoder?

 

[birdman0_o]

The image I posted is very explicit. Seems you just need to follow that...

Unless you do your own work and find another way !

 

[Hasnatsaeed]

f9..so where should i take this 10 outputs now?

 

[birdman0_o]

I think that you would send them to your usual BCD to 7 Segment chip, then attach those chips to the 7 segment displays.

 

[Hasnatsaeed]

each BCD to 7 segment chip takes a 4 bit input..these are 10!.what am i suppose to do with the remaining two?

 

[birdman0_o]

Tie them to ground. You should have been able to understand this for yourself.

 

[Hasnatsaeed]

ive limited expierence with displaying any stuff on any kind of displays.this is my first major purely hardware implementation of what ive been learning in books so far.its my first semester in Digital logic and design and i am just half way through it.so my questions are indeed newbie but thanks for all your time and help..ill come back if i have more questions

 

[birdman0_o]

I don't mean to scare you off. It's easy to grab answers, thinking for yourself is the hard, but important part.