Seven segment display acting wierd.

  • Thread starter kElect
  • Start date
In summary: The IC is the LD5161BG, and it's a display driver. According to the data sheet, it can drive common cathode displays.
  • #1
kElect
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Ok for class, I had this 7segment display(common cathode) and it worked great. Then I bought more, but I bought the common anode kind. And this time, it doesn't work so well. For some reason the numbers change when i wave my hand over the power supply; I am not even touching it. I'm using cd4543 decoder with the ld5161.

..wait i just tried again, and nothing happens but when i pick up the power supply all the segments turn on even though the switch is on 0000 wtf...

can someone tell me why my seven segment display does weird things when i mess with the batteries?
 
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  • #2
Common cathode and common anode will need different circuit methods to drive them
I would hope you are not trying to mix them or use the same circuit to drive one or the other ??

Dave
 
  • #3
The 4543 has to be used with a common cathode display.

To turn a segment on, you make that output high.

If you connected a common anode display in circuit, the LEDs would only turn on if the anode was connected to the positive supply, but then a high drive signal would turn the LED segment off and a low signal would turn it on.

So, you would have to invert every drive signal.

Try to get a common cathode display.
 
  • #4
vk6kro said:
The 4543 has to be used with a common cathode display.

To turn a segment on, you make that output high.

If you connected a common anode display in circuit, the LEDs would only turn on if the anode was connected to the positive supply, but then a high drive signal would turn the LED segment off and a low signal would turn it on.

So, you would have to invert every drive signal.

Try to get a common cathode display.

nope. 4543 is common anode. just tested inverting everything, the light doesn't turn on at all. it stopped blinking though. i think before the resistors were touching so it was acting weird. it still doesn't work though. it stays lighted on the middle segment only now, all others don't turn on and nothing changes when i flip the switches.

is anyone familiar with the ld5161bg? i bought this on ebay.

edit: nvm ur right. the truth table looks like it is common cathode.
 
Last edited:
  • #5
According to the data sheet, it drives common cathode displays. This is shown by the outputs being high for lighted segments.

You connect them like this:
http://park8817.com.ne.kr/COMMON_CATHODE_CIRCUIT.jpg

To make it work with a common anode display, you would have to connect it like this:

images?q=tbn:ANd9GcQYlXuyzbBVZbv7UQCRS-cqYe_59eIAkn6d7AN0h4C7nFcQx9Bh9Q.png
 
Last edited by a moderator:
  • #6
kElect said:
is anyone familiar with the ld5161bg? i bought this on ebay.

never heard of it and nothing on google... what is it an IC ? a display?
have you got the ebay link ?

Dave
 

1. Why is my seven segment display showing incorrect numbers or symbols?

There could be several reasons for this issue. One possibility is that there is a loose connection between the display and the circuit. Check all the connections and make sure they are secure. Another possibility is that there is a problem with the code or circuit design. Double check your code and circuit to make sure they are correct.

2. How do I troubleshoot a seven segment display that is not working?

Start by checking the power source and making sure it is supplying the correct voltage. Then, check the connections between the display and the circuit. If everything seems to be connected properly, try using a different seven segment display to see if the issue is with the display itself. If none of these solutions work, there may be a problem with the circuit design or code.

3. Can a damaged seven segment display be repaired?

In most cases, a damaged seven segment display cannot be repaired. If the damage is minor, such as a loose connection, it may be possible to fix it. However, if the display is cracked or damaged beyond repair, it will need to be replaced.

4. What is the maximum number of digits that can be displayed on a seven segment display?

The number of digits that can be displayed on a seven segment display depends on the size and type of the display. Generally, smaller displays can show up to 4 digits, while larger displays can show up to 8 or more digits.

5. How do I ensure that my seven segment display is displaying the correct numbers?

To make sure your seven segment display is displaying the correct numbers, double check your code and circuit design to make sure they are correct. Also, test the display with different numbers to see if it is functioning properly. If you are still having issues, try using a different display to see if the problem is with the display itself.

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