[SOLVED] 7 segment multiplexing problem

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Dear milan.rajik
thanks
write code with any compiler (c program) i need to display the date and time on 7 segment and LED's I shall add 7 LED diode to indicate the day, I not add it because I have problem in PM LED
I thank your support and thankful to any help

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Dear
I even not complete the interrupt for adjust date and time, i take the code of communication of DS1307 from saeedstudio.blogspot.com he use LCD without interrupt
I try to expand the circuit but I need first to make the date and time works with 7 segment and LEDs
 

Please make a Proteus circuit with & Segment display and zip and post it. You will need 6 SSDs for hh:mm:ss.
 

I attached the Proteus i use 14 SSD and 1 LED to display date and time
 

Attachments

  • clock 20141007 1435.rar
    29.6 KB · Views: 69

Please mention which SSD displays what. You want to drive all SSDs with only 3 74HC595 ?
 

yes
8 output for a,b,c,d,e,f and g and the other 16 output to drive common anode pin in every SSD and one for LED
 

Can I modify the circuit and use ULN2803 or do you want to use the same circuit which you have posted ?

I tested your .hex file and I don't see any flickering in Proteus 8.1. Have you tested in hardware ? If not, please test in hardware and reply.
 
Last edited:
i want to use the same circuit
i have blinking in pm led in Proteus 7.7
i did not try the hardware in real circuit
i notice that led ok when i change it to digital i hope not changed in the circuit i have sent and the 7 ssd have simple blink in some times
 

Post the original project files from saeedstudio or provide the link. Test in hardware and see if there is flickering or not.
 

the original file and the last modify and the testLED as attached
can you check the testLED did all LED ON for all time (there is no blinking) this test multiplexing
did you think that Proteus have unreal simulation, i mean if i apply my circuit it work even when i see blinking in Proteus

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Kindly see the attached
 

Attachments

  • testLED.zip
    29.2 KB · Views: 80
  • clock.rar
    105.5 KB · Views: 69
  • 8051 with DS1307 RTC Code.rar
    85 KB · Views: 73
  • Untitled.png
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  • Untitled1.png
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The LEDs blink in testLED. Only one LED turns at a time. Can you replace LEDs with SSD and test in Proteus ?
 

That what i am saying, how can i make All LED ON because in the circuit i have led and ssd
so how can i fixed this
 

If you use LEDs in Proteus instead of SSDs then you will get blinking but in hardware you will not experience blinking. Do you want to use big SSDs or do you want to build SSD using LEDs ?
 

I have some problems to understand the question, e.g. why do you post three different simulation designs when you are asking about only one of it? What's the relation to the other circuits?

Regarding blinking in the testLED design. I guess you already noticed that the mux control isn't updated in real time. The Proteus seven segment display component has a persistence feature to mimic the perception of a multiplexed display by the human eye. The single LED doesn't have it.

To avoid blinking in real hardware, the multiplex sequence must be repeated fast enough, e.g. > 30 Hz.
 

Dear FvM
Thanks for reply
I have only one problem, the LED blinking, i make a new simulation to clear the problem to other, one reply that 74595 did not have enough current to supply SSD so i make the new simulation for led
so i want to multiplexing led this is the problem and the SSD in real hardware and simulation,
i wrote the multiplexing code and i attached timing diagram what your help to find what it wrong
so how can i make led have this feature with only 74595
 


Dear Engwas,
Your first design was an inefficient Serial to parallel cascade while bit banging on the parallel ports to more S/P registers outputting direct to 7seg decoders whose ouputs are not Mux'd at all. But your input data was Mux'd.

You then implemented my suggestion to cascade 4 shift registers to latch the data in the same but new configuration with parallel outputs.

The only blinking problem is in proteus. Do you want to ignore this or fix the Proteus issue?

The input ports are NOT multiplexed anymore with my change and would never blink in hardware, besides this slow approach n software.

You just clock out 4 bytes of data, then latch. It just updates instantly when you send the Parallel latch signal on the rising edge.

Send a bug report to Proteus.
 
Dear SunnySkyguy
Thanks for reply
So i go with hardware and no any blinking will happen in LED or SSD, i need hardware to work not the Proteus if it has problem with LED to make POV for our eye

Thanks
 

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