3 inputs that can display anything on a 7 segment

[marinekun]

is there anyone who can help us bout our project on logic circuits?
its all about making a design using logic diagrams with a minimum of 3 inputs that can display anything on a 7 segment or on a 14 segment.  like for exmaple displaying the characters  0-9 and 0-F, (note that 0-9 and 0-F cannot be used anymore as a design to our project beacause its already the proffessor example)
thanks....

[Ate Shey]

3 inputs can only make 8 characters.. mukhang mahihirapan ka yata kasi what your professor is telling you is to make your own 3 line to 7 segment converter.. take note that the characters from 0-9 can be easily displayed using the 7447 IC which accepts 4 inputs.. ang ginagawa ng 7447 ay i-convertert yung 4 line BCD input sa 7 line - 7 segment display output.. for example: D=0 C=0 B=0 A=0 ang display ay charater na Zero..

kung bawal gamitin ang 0-9 to 0-F it means gagamit ka ng other characters like
KLMNOPQR .. it requires a 14 segment decoder ic.. kung bawal gumamit ng ready made na 14 segment decoder, that means kayo ang mag-dedesign.. basically, ang gagawin mo ay 3 line to 14 segment decoder using logic gates alone.. if you are familiar with "Karnaugh Map" you are going to do it 1 by 1 on each output pin of your 14 segment decoder..

another viable option is to make your own character generator set.. for example para magawa mo ang letter K, take note of all the logic gates you need para ma-display mo yan.. ( always have your Karnaugh Map ready otherwise mamumulubi ka sa dami ng gates na kailangan mo) .. then you build another circuit that displays the letter L,M,N,O,P,Q and R ..  pag-natapos mo na yan it means na-convert mo na yung 14 segment into 8 lines.. now all you need is a 3 line to 8 line converter like 74LS138 and you are done..

[marinekun]

uhmmmmn...
not exactly 3 input poh...require lang poh ng prof nmin is 3 or more input, where 3 input is the minimum requirements....
and the use of decoders/encoders are allowed,
naisip koh na din poh un KLMNOP... na characters but medyo nahihirapan akoh sa design...
the other one na naisip koh is the calculator pero based sa web maxado na complicated ung calculator...
so theres no other choice than designing KLMNOP...circuit but on our class were not yet stuying such decoders/encoders thats why i didnt know much about it...

[Ate Shey]

alam na ba ninyo kung paano nag-wowork yung 4 line to 7 line decoder such as the 7447 ? .. may schematic diagram yun sa datasheet niya which can also be modified to produce other characters.. yun nga lang like i said before masyadong maraming gates yun kung kayo mismo ang gagawa ng decoder..

[marinekun]

nope... ndi pa nga poh kmi naiintroduce ng prof nmin sa decoders eh...
kya wla poh akong idea sa 4 line 7 line decoders and how it is works...nagkataon lang na may clasmate kami na ahead samen na nag suggest sa prof nmin na pwede gumamit ng decoders...
possible poh ba na isang decoder IC lang gamitin pra makapag produce ng 10 characters such as K,L,M,O,P,Q,R,S,T, and U?

[Ate Shey]

since bawal sa inyo gumamit ng 0-9 at A-F it means hindi na kayo puwede makagamit ng 7 segment display at 74LS47 Decoder IC..

it means gagawa kayo ng sarili ninyong 14 segment decoder which is just composed of Logic Gates.. mahabang proseso not unless someone on the forum can suggest a ready made IC that can drive 14 segments..

i suggest na basahin muna ninyo yung datasheet ng 74LS47 and study how it works.. once you know how the 74LS47 works you would be able to build your own decoder..

[marinekun]

uhmmmn...
ndi nman poh sa bwal gumamit ng 0-9 and A-F common na poh kasi un.. our section is composed of almost 30 groups en dapat daw ung isusubmit na design wlang kapareho sa ibang groups,
since common na ung 0-9 and A-F im sure na may iba na rin gagawa nun, masasayang lang ung pinaghirapan nmin kung may makakapareho kmi ng design...
pero aralin koh pa din ung datasheet ng decoder ic 74LS47...

[Ate Shey]

madali lang gumawa ng decoder ang mahirap lang ay kung marami ng lines or outputs na kailangan.. yung 7447 4 input tapos 7 outputs so basically kinokonvert mo lang yun using Logic gates..

ang pag-gagawa ng decoder ay magsisimula muna sa paggawa mo ng "truth table" for example sa 7447 ang inputs mo ay D,C,B,A tapos ang outputs mo naman ay Seg A, Seg B, Seg C, Seg D, Seg E, Seg F, Seg G.. each output line corresponds to 1 LED like the one in this picture..



in your case naman ang inputs mo could be 3 or 4 inputs tapos ang output mo ay 14 lahat so bale.. Seg A, Seg B and Seg XX..



once meron ka na ng truth table all you need to do is figure out kung ano anong mga gates ang gagamitin mo.. siyempre "sum of products" ang typical na gagamitin mo which is mostly composed  of AND gates, OR gates.. then para kumonti ang kailangan mo na gates, gagamit ka ng "karnaugh map" to simplify your equation..

[marinekun]

yeah understood koh na poh...
galing galing...hehehehe...
dapat kau nlang naging prof nmin eh...
gagawin koh nlang poh ung truth table up to simplification using k-map den popost koh nlang let d2 sa forum for checking....thanks poh...
thank you... thank you....

[Ate Shey]

mag-iistart ka talaga sa truth table.. pero define mo muna kung ilang inputs ang kailangan mo tapos.. for example: 4 input lines driving a 14 segment display.. gagawa ka ng truth table with 4 inputs tapos ang output mo naman ay isa for each segment..

kaya kung 14 segments eh gagawa ka ng 14 truth tables for each one.. ikaw ang bahala mag-fill up sa truth table depende kung ano ang gusto mo na pailawin na segments based on your inputs.. once established na ang truth table, it is just a matter of converting the truth table into Logic Gates..

so in this drawing, may truth table ka for Segment A,B,C, ... up to Segment G1, G2, etc..