Binary to Hexadecimal 7segment Display

Discussion in 'Electronics Resources' started by glenn_boy13, Dec 19, 2012.

  1. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    Hi, Ive been wondering if there is another way to display the 4 bits binary digit into HEXADECIMAL (7 segment display)?
    I know I can use 74ls47 or 74ls48.


    but it has only 0-9 useful outputs.

    [​IMG]

    There is no way to modify the 10 to 15 output of such ICs, right?

    OF COURSE I already did kmapping. But I will have to have many ICs, even though I compressed the equations(simplify). The circuit is still quite large for me.

    PS: I need some answers please as much as possible.
  2. absf

    absf Well-Known Member

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    I know there are 4 ways to do it.

    1. use a 32x8 TTL prom or the smallest EPROM like 2716.
    2. use a pic like 16F628 and write a simple program.
    3. use special CMOS chip like MC14495 or DM9368.
    4. Buy special hex display like TIL311.

    Allen
    Last edited: Dec 19, 2012
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  3. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    *as soon as possible xD
    Thanks sir Allen!
    I will check those chips.
    Anyway, I hope such chips are available in my country. thanks again.
  4. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    hi sir allen, I sent you an email. anyway, I wonder if there are still other way other than using the ics you have recommended. they are not available in my country. I know how to use microcontrollers, but not proms. I just want to use 1 IC to display 1 hex number.

    Is it possible to use multiplexer/decoder?
  5. absf

    absf Well-Known Member

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    If you know how to use a MCU, then you should use MCU...

    I recommend 16F628A. How many hex digits do you need?

    The 2 chips in item 3 are decoders. Didnt you download their datasheets and take a look?

    Allen

    Attached Files:

  6. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    Hi sir Allen. Thanks for your time.
    Im sorry, I didn't say that I only know how to use Arduino. :))) And sadly, I only know some basics, but I understand programming so well. Im only 4th year college, and my embedded systems subject is on my 5th year. Therefore, we are not allowed to use any MCU. However, the ATmeg328p-pu of arduino is quite small, and I want to use that if there is no more way to solve my problem, because probably my professor won't notice that 28 pin chip. hehe.
    But Im still waiting for the replies in my thread:

    http://arduino.cc/forum/index.php/topic,138489.0.html

    Anyways, thanks again. I only need 2 Digits. Did I mention that this is for my computer architecture? Me and my classmates have to build a SAP-1 computer. And every 4 bit output of each computer of such computer must converted to Hex!

    I can see that the CD4511B is the same as the 47/48. BUT, the outputs for A-F produce blanks. I wonder if there's a way to reproduce A-F in 7 segment using that CD4511B.

    Lastly, if no one will answer in my arduino thread, I guess I will have to use basic gates to convert 8 bits to 2 hex digits :((
    That would be tough for specially for me, Im the only one in my group who knows how to design a circuit very well.
  7. absf

    absf Well-Known Member

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    Since you only know Arduino, I hope it would be OK if I show you how I do it with a PIC. It only took me an hour to figure out the program in Pic Basic. Of course the C experts here would take only a couple of minutes.

    Nothing is stopping you to learn embedded controller before your lecturers teach you the course. There are so many resources on the web that you can easily learn pic and avr. And they are much cheaper than Arduino.

    No you didnt. Because you put your question under electronics resources.

    Modifying 4511 to display A-F might be possible. But that would require lots of work. I think it's easier to just use a 74154 decoder with some gates.

    Allen

    Attached Files:

    Last edited: Dec 21, 2012
  8. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    hey sir allen, Thank you sooo much for having a time to reply to my questions. thanks thanks thanks ^_^.

    1. I understand what youdid in your attached screenshot. I can do that in my arduino. But see, Arduino has only 13 digital i/o pins :(( ohhh! I forgot! I almost forgot that I have another chip! It took me almost forever to burn the bootloader program into my extra atmega328 chip. I can use them! Thank God!. One Hex Digit for One Chip.
    I would like to use such small pic chip than this 28pin chip of arduino. But I don't have any programmer for pic.


    2. Thanks again sir allen. ^_^. But, do you mind to show me on how to use 74LS154 with some basic gates? I think that would be a lot easier than using only basic gates(using logisim or a scratch paper, Kmap the inputs/outputs... simplify the equations using only 2 input gates).
  9. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    hey sir, by the way, the reason that I wanted to push myself to use just ONE MCU chip, is that, the chance of getting caught of using MCU in my project would be small. :)) haha! Normally, in most of the arduino projects, they use shift registers. one 8 bit shift register for each 7 segment display. And If I use only one atmeg328p chip I will have to include two pcs of 74ls595 shift register ICs. And my professor wouldn't notice the big chip because of the two small ones.

    thanks ! ^_^ But I realy want to know how to use the mux 74ls154. thank you so much! Im glad you are there
  10. absf

    absf Well-Known Member

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    See post #27 on the link here to get some idea how to implement it.

    http://forum.allaboutcircuits.com/showthread.php?t=78011&page=3

    Allen
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  11. absf

    absf Well-Known Member

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    You can program the Arduino to do what the PIC is doing without using serial shift registers like 74HC595. To display 2 HEX digits with one 16F628a is also no big deal. Just has to add a simple mux and take care of the display timing.

    Allen
    Last edited: Dec 21, 2012
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  12. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    hi again sir allen. I already checked out your post #27. I just couldn't understand what you want me to know.

    1. Yes sir, I know how to use just one MCU in arduino to display two hex digits in two 7 segment display WITH one 4-BIT Input. That will consume (8 + 8 + 4) 20 pins of the chip.
    :( But I need another 4-bit input to make a total of 8 bits input.

    You said that I just need to add a simple multiplexer, right? Could you please sir show me how to use the mux with your pic and your codes? I will just have to study them.

    Anyway, about your mux post:
    http://forum.allaboutcircuits.com/attachment.php?attachmentid=49848&d=1355743793

    The inputs are the ABCD, right? and the outputs are the Y0 to Y4. How is that related to displaying hex digits in 7 segment? hehe.
    is it connected to this image (u2 and u3)?
    http://forum.allaboutcircuits.com/attachment.php?attachmentid=49847&d=1355743793
    I don't know what is RN1 and RN2.
    And I know that the 74ls47 is used only to display decimals. A-F are useless.

    darn, sorry if I didn't get any of your suggestions.

    Okay, to finalize... These are the ways I think I will do/use.

    1. Because there are people who replied in my arduino post: http://arduino.cc/forum/index.php/topic,138482.0.html , I think, I will try their suggestions later. that will use shift registers. But, Im not yet sure if I will succeed in using that way.

    2. The one you suggested sir allen, using one MCu chip with multiplexer.

    3. Or the mux with basic gates.


    thanks! I don't know if you will still help me. haha. I know the feeling of being questioned again and again.
    Last edited: Dec 21, 2012
  13. absf

    absf Well-Known Member

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    In post #27, you have to use Excel to construct 4 bit binary (input) and 7-bit a-g of 7 segment LED (outputs).

    The example that I made is for binary to 2 BCD digits. From the table you can construct the circuit using 74154 and NAND gates which should give you the Binary to Hex output for 7-seg led.

    I have drawn the circuit for 2 digits with a mux for the inputs. But my simulator has trouble with the VEE of the 4053 cmos mux and refuse to run. The software is still in progress and not yet tested. You might use it as a ref for your atmega328 or Arduino and see you can make it work.

    Allen

    p/s stop calling me sir pls just call me Allen will do.....:p

    Attached Files:

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  14. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    Thanks again for your reply "Allen." hehe. Im only 19 years old, so I have to respect you. ^_^

    1. Im very sorry because I have to ask you again about the mux with NAND Gates. ughhh, I didn't get it again. :((
    http://forum.allaboutcircuits.com/attachment.php?attachmentid=49848&d=1355743793
    In that picture, the outputs are y0 to y4. so we have a tota of 5 outputs, right? :) How am I suppose to connect them to the 7 LEDs of the 7 segment display? :( I should have 7 outputs.

    2. What is the use of the PNP transistors? Are they really necessary? Of course I know what transistors can do. heheh. I just don;'t know why did you put such things. :)

    3. Whats that RN1(rx8) thing?

    4. uhmmm Allen, what software do you use? In my school, we use Multisim. It is similar to your software, but we, the computer engineering students don't use such software. hehe. we believe thats only for the electronics & communication engineering students. Lastly, I believe you already know the multisim software, right? ^__^. We always use such software for our Logic Circuits. IT can make and simulate different Logic Circuits. For instance, the one that you made in excel, I too can make such a table (4 bit inputs and 8 bit outputs for a-g) and then tell the program to make a logic circuit. Either using only NAND Gates or using only 2 bit input logic gates.


    THANKSSSSS!!!!!! Wow, you are really a big help! ^__^ Don't worry. Im learning many things from you.

    glenn
  15. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    Last edited: Dec 22, 2012
  16. absf

    absf Well-Known Member

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    If you show me the truth table of your Bin to Hex. I can show you how to connect the 74154 to "a" segment of the LED. Fair?

    The PNP is acting like a switch. When the base is at logic Low, the transistor conducts and the common Anode of the LED would get +5V. If you want to take a risk, you can connect the RA4 and RB0 directly to the Anode of the LED. But if there is a short on your LED, your mcu would get toasted.:D

    8x 220ohm resistors in a 16-pin DIP package.:)

    I used Proteus Pro for schematic and simulation and ARES for making PCB.
    I know multisim but never used it. It was quite good too. But I think you should learn LT Spice IV. Most of the experienced senior members use it. SO if you have any circuitry problem it would be easier to communicate with them.:)

    I tried but it doesnt work.:(

    Allen
  17. absf

    absf Well-Known Member

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    Hi your truth table is incomplete and the table is shadowed by another small window.\ so I cant see the details.

    Could you pls post your picture here in PNG or PDF format so I can see it easily.....;)

    Allen
  18. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    hi Allen, just got home! haha. I see, Rx8 is a set of resistors.

    uhmm

    ok sure, Ill show you the truth table. just show me how to connect some or one outputs to some or one led/segment of the 7 segment display using Multiplexer/Demux/Decoder. Oh by the way, haha, 154 is a demux/decoder, right? ^_^

    here:
    http://i48.tinypic.com/219bc.png

    ^_^ Thanks so much again!!!!!~

    One thing I hate about my country: THERE ARE MANY UNAVAILABLE ICs HERE! :( not to mention the corrupt government officials. DM9368 is manufactured by FAIRCHILD, and the good news is, there is one branch of FAIRCHILD here, but located very far from the capital city. ughhhh!!!!!!!

    glenn
  19. absf

    absf Well-Known Member

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    In your truth table there are 78 "1" and only 34 "0"....count them.

    If I want to qualify with logic "1s", I would use AND gates. Instead I'll use NAND to qualify logic "0s".

    Study my circuit carefully. Segments "a" to "c" are already done for you. So you just continue with the rest of the segments "d-g". Do it in your logicsim or multisim and see how it turns out. The 7-seg LED should be common Anode.

    If you still dont understand how it works. Use a smaller model say 74139 (1 of 4 decoder) to display digits 0-3 using your table.

    Allen

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    Last edited: Dec 22, 2012
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  20. glenn_boy13

    glenn_boy13 Thread Starter New Member

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    hi sir allen. MERRY Christmas! thanks for all your help! :)
    I ended up in using one ATmega328 MCU plus two 8-bit 74ls595 shift register.

    If anyone here, or anyone from somewhere and luckily you have searched this thread, has the same problem, and you want to use arduino and shift register with inputs to display hex to 7 segment, just contact me :)

    www.glennvon.com Im willing to help. hehehe



    thanks sir allen!!!! :pP
    Sir alen, I would like to seek some help from you about PIC in the near future. hehehe. do you mind? ^__^

    glenn
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