BCD Clock

[demo]

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

 

[mmm]

demo wrote:

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

You must reload the hours counter with 01 instead to reset the counter
to fix, You must switch to a presettable counter if you are not using it
a suitable part can be the CD4029 chip or 7416x ( x = 1,2,3,4) or
similar part

in alternative you can count like in Italy

00:00 midnight
.....
.....
11:59

00:00 again for half day

and so on

11:59 a minute before midnight

and eventually add 1 ( one ) to hour digit before display

 

[Richard Henry]

"demo" <demo001@gmail.com> wrote in message
news:1122143246.072699.26460@o13g2000cwo.googlegroups.com...

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

Use military 24-hour time, running from 00:00 to 23:59.

 

[Arie de Muynck]

"demo" ...

I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

Are you a technical person? This is the change to amaze your friends!

Just do the right thing and rollover to 00:00:00 after 23:59:59.
And also display a (sortable) date format like 2005-07-23.

;-)
Arie de Muynck

 

[keith]

On Sat, 23 Jul 2005 11:27:26 -0700, demo wrote:

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

Others have already jumped on my fix (military time), so I'll suggest the
hard way. Use a gate to detect 13 hours and do a parallel load of '1'.
You will need a counter with a parallel load (direct set, or some such
thing). I better way would be to detect twelve and use a counter with an
enable (detect 59 minutes) and a synchronous load.

--
Keith

 

[Ben Bradley]

On 23 Jul 2005 11:27:26 -0700, "demo" <demo001@gmail.com> wrote:

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

There must be a solution at <http://leapsecond.com>.
-----
http://www.mindspring.com/~benbradley

 

[Chris Carlen]

demo wrote:

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

You might have a reason to be using logic chips, but look into what
microcontrollers can do for you. You can implement a very feature-rich
clock using a micro, and change it any time and any way you want. To
accomplish the same feature-richness with logic chips would be nearly
impossible. The only other alternative, and one which you should also
consider if this is more of an academic exercise, is to use a CPLD or
FPGA. Then you can develop logic design skills instead of software
skills, while avoiding the limitations of discrete logic chips.


Good day!




--
_____________________
Christopher R. Carlen
crobc@bogus-remove-me.sbcglobal.net
SuSE 9.1 Linux 2.6.5

 

[demo]

thanks

 

i`m having problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes)

The BCD clock at:

http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm

Works like this:

You get a falling edge at pin 1 of the hours counter which advances the
counter to 13 hours. This produces a high level at pins 2 and 14 which
resets the counter to 0.

So you have that much working.

The reset signal stays high for a few milliseconds determined by the RC
at pin 11 of the inverter. Pin 12 of the next inverter will move high a
short time after pin 10 moves low, which applies a high level to pin 1
(clock input) of the counter. When pin 10 moves back high, pin 12 will
move low a short time later applying a falling edge to the counter
which advances it from zero to 1. So, it's now 1:00 PM instead of 0:00
PM.

Should work with the right parts.

-Bill

 

[Glenn Gundlach]

demo wrote:

thanks

The power went off today and the 'goofy clock' was happily reading out
the 'fail' time and date, restore time and date, also for the last 2
power failures. It stores 8 events. This is a microcontroller based
device with maybe 1200 lines of assembly code. I also have a triple
display version to do multiple time zones with 12/24 hour mode
selectable for each zone. Are you doing a BCD clock as some sort of
exercise to show it can be done? To prove a point? A class assignment?
Dammit, I can do it?

Chris Carlen is right about the feature rich possibilities of the
microcontroller world. Next software revision of goofy will include a
WWVB receiver from Galleon.

I used to prefer hardware versions because they seemed simpler but the
flexibility of microcontrollers is so great that I only use the
hardware for things too fast for the controller, even then with PLDs,
CPLDs, etc. A long time ago a friend pointed out that the only
difference between hardware logic and the computer is the sequential
nature and temporary storage of intermediate results. Reprogramming
beats the the hell out of trace cuts.

GG

Always make NEW mistakes.