My 8-bit chip is acting as a 5-bit chip

Discussion in 'The Projects Forum' started by u-will-neva-no, Aug 9, 2011.

  1. u-will-neva-no

    Thread Starter Member

    Mar 22, 2011
    230
    2
    Hi everyone! Im using the 74HC595N IC chip. What is happening is that My "Binary counter project" Is not performing correctly. Basically, Pin 4 on the IC is acting as Q0, pin 3 as Q1, pin 2 as Q2 pin 1 as Q3 and pin 15 as Q4. The 74HC595N data sheet said that the bits would be shifted in order but my first four LEDs, representing each bit do not work. It seems like the output pins are of the wrong order, however I cant get the three LED pins to work when i change the output Pins on the chip. I also have an identical chip and that is doing the same thing.

    Im happy to take a picture to show all the wiring, and also a video if that would help. I will take a picture of it in a moment, just going to neaten up the wires :) Thanks for reading and hopefully someone could help me on this issue!
     
  2. u-will-neva-no

    Thread Starter Member

    Mar 22, 2011
    230
    2
    I think its ok now :)
     
    Last edited: Aug 9, 2011
  3. u-will-neva-no

    Thread Starter Member

    Mar 22, 2011
    230
    2
    Just to clarify, QA-QH are attached in order from the LED on the left to the right led. The 5th led is lights up first when the binary number of 1 is sent, and the binary number 8 causes led 1(nearest to the IC ) and the 5th led.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Try sending out this series of numbers in order, and see what LEDs light up:
    1
    2
    4
    8
    16
    32
    64
    128
     
    u-will-neva-no likes this.
  5. u-will-neva-no

    Thread Starter Member

    Mar 22, 2011
    230
    2
    Oki doki,

    1 - no led lights
    2- no led lights
    4 - no led lights
    8 - led 5 lights (where i have taken pin one to be closest to the IC)
    16 - led 4 lights
    32 - led 3 lights
    64 - led 2 lights
    128 - led 1 lights

    So my issue is with led 6,7,8 which are connected to pins 5,6,7 on the IC respectively. What is also strange from this is that it is as though the binary representation of 1 through 7 are not working. The code is not an issue because it is from an arduino book that I am using however. I have a delay of 5 seconds between each binary number representation of the lights so why does it straight away come up with the binary number representation of 8?
     
  6. u-will-neva-no

    Thread Starter Member

    Mar 22, 2011
    230
    2
    Btw all the LEDs work, I just tested them with the pins that are outputting from the IC..
     
  7. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    Have a look at the blue and red lines on the breadboard.
    Where there is a break in the line it normally means there is a break in the connector, so adding a bit of wire to bridge the gap should solve it.
    I've fallen for that one before.
     
    u-will-neva-no likes this.
  8. u-will-neva-no

    Thread Starter Member

    Mar 22, 2011
    230
    2
    OMG i feel so stupid!!!! Nethertheless, it kept me stubled for two days! Thank you! lol!
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Yes, that same thing has "bitten" me before - and a number of other folks on here too. That's one of the things you don't forget after it happens to you.
     
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