• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

BCD to DUAL seven segment display

Status
Not open for further replies.

lepass_7

New Member
Hello,
I am trying to create a countdown timer using PIC16f690, i ll use 3 seven-segment displays. The first one is for counting hours (max 9 hours) and the other two i would like to count the minutes. In my program i am storing the hours in a register (HOURS) and the minutes in the MINUTES register when i want to display the contents i use 4511 BCD to seven segment decoder. Using this approach i can solve the problem for the hours but i cant display the minutes above 9 minutes. Is there any IC that decode BCD to dual seven segment display?
Thank you in advance
 

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
You could do three directly from the 690 if you use PORTC for the segments and PORTA or B for the segment drivers.. If you put 270 ohm resistors on PORTC they will have enough juice to light the segments.. Then there is no problem with minutes, hours or whatever. No other parts required.
 

lepass_7

New Member
First of all thank you for answering me. The solution you provide me i think its a good one, but this requires to use 2 PICs for my project because i need two ports more for my project and a lot of coding. I would like to know if anyone can suggest any IC like 4511 which is a decoder which can decode and light up two seven segment for example if i want to show the 59 minute i will send to the decoder the bcd 00111011 and the decoder with 14 output will use the first 7 output to write to the first display the number 9 and the last 7 outputs to write the number five to the second display. Is it possible? Is there any IC? (Please take a look to the attach picture )
 

Attachments

alec_t

Well-Known Member
Most Helpful Member
You will need 2 decoder chips. AFAIK there's no dual version of the 4511.
 

lepass_7

New Member
Thank you alec_t. The problem is if i had the 59 number which in binary is 00111011 i must send to the first decoder the number 5 which in binary is 00000101 and the second the number 9 which is 00001001. So i believe the solution is to recognize the binary number and then if the number is 59 i will move to the PORTC(which is my output) the number 0101 1010, so the first 0-3 bits will go to the first decoder and the second 4-7 bits will go to the next decoder. But this solution its going to be very large due to the part which i must recognize the number and convert it.
Any other ideas?
 

alec_t

Well-Known Member
Most Helpful Member
One way or another you're going to have to write code to do it!
 

lepass_7

New Member
Yes i know that and i ll do that i am just asking if there is some other way to do it more efficient and easy.
So i ll start coding
 

alec_t

Well-Known Member
Most Helpful Member
Why not split the MINUTES register into two (UNITS, TENS)? Register UNITS counts seconds 0-9 and, on roll-over, register TENS is incremented. Only a few lines of code.
 

lepass_7

New Member
Thank you again guys, i think I ll try alec_t suggestion or maybe i ll use one seven segment and every unit it will mean 10 minutes. I ll come back later with the result.
Thank you all again!
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
I'm lost. Why not:

1. Do your counting in BCD?
2. Convert to BCD prior to display?

Latch each BCD digit?
Directly multiplex the display. Trick: Don't forget about inter-digit blanking.

Your working register(s) dont have to be the displayed register.
 

lepass_7

New Member
I came up with the best solution (i think). The IC 4511 comes with a build-in function for latching data so i used that, i placed three seven segments with three 4511 when i want to change the display i use the LE/STB' pin so i just need 4 bits for the bcd and 3 bits (it could be possible with 2 bits using a mux) for "selecting" the right seven-segment display!!!
Again thank you all for your time!!
 

Attachments

Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top