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I suppose to design a clock using seven segments

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PA3040

PA3040

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Dear All
I suppose to design a clock using seven segments

12 : 25 : 56

01 : 04 : 2012

as per above I need 14 seven segments. please advice how my I manage the ports
my mcu is 16f877a
RTC DS1307

please advice
 

There are ics from Maxim that can drive 8 LED digits (see MAX6951) with just 3 connections to the uC (serial interface). You could use a couple of those ics.
 
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Dear sky,
Thanks for reply
As i know this IC (MAX6951)is little bit hard to find in the market our country. can I have widely used method, instead of you suggested

Thanks
in advance
 

Dear Arch,
Thanks for reply
Can you please explain the operation of 4094 IC
Thanks in advance
 

4094 has 8 bits output. you can use the outputs for each segments.
untitled.GIF
 
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I think, date, month and year need not always be displayed
if you want to display, you just simply press the button, so only use seven (7 segment)
 

Dear Arch,
Thanks for reply
Can we drive the seven segments with multiplexing using this method
please advice
 

Dear Arch Thanks for reply
1.
image of your reply in post #6. can we use this wiring diagram for multiplexing
2.
I need to write a program to shift logic level 1 from Q0 to Q7 using 4094
can you please write simple code from assembly language
please advice
 

I have to draw it first. But let's see my PCB design. it's very easy. I add 7406 as buffer because i use more than 150 7-segment in that application. Since you only use 14 7-segments, this 7406 won't be necessary (please check fan out of your chip).
untitled.GIF

I'm not familiar with PIC, let me tell you the algorithm :
OE is always high.
we have 14 7-segments

Send Data of segment that connected to Q7 of 14th digit.
Set Clock then Clear it.
Send Data of segment that connected to Q6 of 14th digit.
Set Clock then Clear it.
....
Continue till Q0

Send Data of segment that connected to Q7 of 13th digit.
Set Clock then Clear it.
Send Data of segment that connected to Q6 of 13th digit.
Set Clock then Clear it.
....
Continue till Q0

and Continue till 1st digit

Set Strobe then Clear it.(here, new value will be showed)

that's all, it is easy, isn't it? it won't be easy if it is multiplexed because we need to refresh display every time but we still need to read DS1307.
 
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Dear Arch
Thank you so much for reply, that is great help for me


Now I need use 4094
can you please give me a algorithm for 4094
I need shift Q0 to Q7 logic level one (1)
Ex

00000001
00000010
00000100
|
|

Thanks in advance
 

Code: 
before:
    7654 3210
    XXXX XXXX

1st:
Data=1
Clock=1
Clock=0
Strobe=1
Strobe=0
>>
    7654 3210
    XXXX XXX1


2nd:
Data=0
Clock=1
Clock=0
Strobe=1
Strobe=0
>>
    7654 3210
    XXXX XX10

3rd:
Data=0
Clock=1
Clock=0
Strobe=1
Strobe=0
>>
    7654 3210
    XXXX X100

...
 
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use cd4511 for bcd to seven segment converter.
and use transistors to selects the seven segments.

when 1st 7segment select then send data then select other and send data likewise do for all and you will need to adjust the time as per crystal you use and controller you use.
 

first of all give the details of the 7 segment, whether it is small in size or larger like 4inch 7 segments?

if it is a small one just use cd4511. that is enough. if it is 4 inched one go for uln2003
 

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