Digital Clocks - Dividing by 60 With 1 Chip

http://focus.ti.com/lit/ds/symlink/cd4059a.pdf

Thanks, but I don't see a solution here. I had looked at 74hct4059. The example that included 60 appeared to have a multitude of other chips to program it. I couldn't find an example in your link that includes 60. Am I mistaken?

From the 4059 datasheet:

You still have to switch it from master preset to a mode after at least 3 clock cycles by building fig. 21 which has another chip plus a multitude of other components. Even if it was a one chip solution, it has a large footprint. I was hoping for a 16 pin chip, as board space is a premium. I could put a 7492 and a 7490 in the same space as this chip. It is intriguing for future projects, however.

I have used GAL's for such things years ago.

But GAL's are relatively dumb and require chip programmer, which isn't always cheap.

Also, they are practically obsolete.

You might want to look into CPLDs, which are cheap, can be programmed in-circuit, much of design software for them is free or cheap and require just an serial cable programmer ( which is also cheap or can be simply made ).

I used to play with Lattice but they have charged quite a bit for their SW ( don't know if they still do). Other good choice might be CPLD's from Xilinx.- YOu can choose between their native, relatively bland XIlinx CPLDs or those they bought from Philips- famous CoolRunners.

Their SW package - Webpack is free.

Yes: GA I was going to suggest the 4040:-

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-2048-5-ND

with some "glue logic" to AND the Q₂ to Q₅ bits.

rcapper has complied with "one chip" requirement.

Hi rcapper,

Thanks, your answer fills the bill. I hadn't thought of using diodes as "wire AND gates". I did that years ago to add a master valve to my sprinkling system timer. Since this chip will do 4096, I could use Q11,Q10,Q9, and Q3 to divide by 3600. That way I could supply 60Hz with a power transformer instead of the 1Hz time base I was planning on. I could even use 7 diodes with a switch to choose 1 or the other. I give you a GA.

-S

Can you use the 7490 for both the div by 10 and div by 6?

First 7490 div by 10

60 Hz pulse to pin 14

Connect pin 1 to pin 12

Connect pins 2, 3, 6, 7 tied to pin 10 (Gnd)

Connect pin 5 Vcc

Connect pin 10 Gnd

Connect pin 11 output to 2nd 7490 div by 6

pin 14

Connect pin 1 to pin 12

Connect pin 2 to pin 9

Connect pin 6 & 7 tied to 10

Connect pin 10 to Gnd

Connect pin 5 to Vcc

Connect pins 8 & 3 output to next stage

Hi,

I saw that schematic on the web, but I don't understand it. I'm not going to build what I don't understand. There was no explanation and no values given for the resistors. With rcapper's solution I only need 1 resistor.

-S

Only the first two blocks apply.

OK, after looking at the data sheet and the connections shown, I see the /2 and /4 outputs are ANDed to the reset by an internal gate. I wonder why the data sheet didn't show /6 as a possibility. This should work, but is still a 2 chip solution. I like the 1 chip solutions presented here. Thanks anyway. What do you suppose the diodes and resistors are for in the lower blocks? I had assumed they got lazy with the schematic, and they all had them.

I think the resistors and diodes (LEDs) are for testing otherwise there would have been a seven segment decoder and display there.

Jon

Aha! Since those are the QA to QD outputs, I think the diodes are LEDs. It's a BCD readout! I was considering that for the seconds in our clock, since I don't need any decoder for that.

I am running that on my breadboard with led and seven segment monitoring.

Works good so far.

Jon

You have some great answers, but you may not have understood them all.

All you need to do is take the "6" count output of your counting chip (you did not mention which chip(s) you are using) and carry it back to the reset. That way it counts to 6, resets, counts to 6......

I hope this makes easier to understand the good posts you have already received.......

(Going back on-topic-ish) ...

If I still had a programmer handy _{(note to self - put "programmer" on the list*)}, I'd go for a PIC. Could use the titchiest one available, & do it with one I/P & one O/P, leaving loads of spare I/O for whatever (alarms? Idunno).

_{* My old programmer was "universal" (EPROMs, PICS, PLAs etc), but tied to a dedicated parallel I/F card, which wouldn't run faster than the (?8MHz) ancient lump it lived with. Dumped when I had to relocate in a hurry. Shame, 'cause I wrote a PIC assembler which generated ASCII hex for input to the programmer software . Ah, the good old days!.}

Even one of those fairly new Basic driven "PICAXEs" should be fast enogh to do the job easily....are an Arduino of one type or another....easy to program and learn...

See:-

http://www.arduino.cc/

http://tech.groups.yahoo.com/group/picaxe/

Thanks Andy. As JohnDG said, a programmable logic chip would work, but I have no tool for that. I think that is a little complicated. Can an old dog like me learn a new trick? Perhaps.

I speak as though I know what I am talking about, but I am just starting with the PICAXE PIC controller myself.

I have already read extensively about it and you really can't go wrong I feel, its so simple to program in a form of Basic, that gets compiled (also indicates what is wrong if something is wrong with your program), there is a simulator (slow) but it also demonstrates with simulated LEDs what is going on very accurately.

Also all the software tools you need are free to download and use, therefore really cheap! But there is really nothing to beat it for the private person.....I have recently researched extensively myself many PICs as I want to build LED light chasers and PWM controllers.

The only other chip that comes near to being so easy to use and cheap is the Arduino......which is why I sent you links for both....but for me the PICAXE has the edge in simplicity and ease of use......

A simple counting program with a "For...next" loop to 60 should do it......some sort of schmitt trigger to condition the signal from your clock timebase should do it......the PICAXE(s) can run with an internal timebase of 4 Mhz or an external up to 20Mhz with some of them.....The simple 8 bit version should do it and costs only a few $$$.

Even in basic they can be programmed to count in Milliseconds!

Download the software, install it on you PC and start playing, its really easy.

Have fun......

I assume you are after a single-package solution, not merely single IC.

The 74HC525 will do the job (I expect that there are other options in the HC range), but it is overkill

Then there are loads of suitable digital alarm clock chips.

Sanyo LM8560 (for example) will do what you require. In fact it will do the complete digital clock, including providing alarms and time set functions. Then there wer the MostekMK5017 and MK50254 (equivalents are available here, albeit grossly overpriced). Practically any eprm/eeprom microprocessor can be programmed to do the job (from about $5, but not worth it unless you already have the E(E)PROM programmer).

The difficulty in finding a well-priced integrated device is probably that most chips these days are designed to run from a 32-kHz crystal. In fact, even 20 years ago when we wanted to resurrect a classic 100-Volt line type clock, we found the cheapest option for deriving the pulse was to cannibalise a fully-working digital alarm clock - the central bar on the MSB of the seconds output has a period of a minute - but we still needed an RC to generate the pulse to advance the clock.

"I assume you are after a single-package solution, not merely single IC."

No, the object is not to save money - a ready built clock can be had for 5-10 bucks.

My son likes out of the ordinary clocks. We already have the hour and minutes done. The present components took up more space than I wanted, so trying to figure out if I can get a seconds display too, or just finish it.

The

MC14536BCP (or HCF4536BEY from STMicro) should do the job for you in a 16 pin DIP package. It has two programmable counter sections, you can use the 8-bit to do one division and the second one to do the other. It should not require any glue logic. It is available from Mouser electronics .

http://www.mouser.com/Search/Refine.aspx?Keyword=MC14536BCP

What am I missing - I couldn't see an obvious way to use this chip to divide by anything other than 2^N (i.e. not 60)?

Sorry, a typo on my part, I meant the MC14566BCP which was intended for just this kind of application. However, this part from On Semi appears to have been discontinued from them, I do not know if it is still available from second sources or perhaps can be found on e-Bay. It would have fit the one chip solution nicely. ST Micro or Fairchild often made the same chips as a CD4566.

Sorry, haven't found a source for this chip yet.

Agreed - that was indeed a divide-by-50/60 chip. Unfortunately, Freescale semiconductor nominally transferred the part to ON semiconductor in 1999, and ON semiconductor do not list the part as a current product.

These people list the part as "in stock". It is also listed by a large number of mainland China agencies - with both Motorola and ONsemi listed as the source. I have no idea whether these are left-overs from last-time buys, or they are manufactured by Chinese fabs using Motorola or ONsemi's old masks.

Looks like a good solution. I give you a GA (on this post).

Thank you, glad to be of help. Too bad these semi companies are dropping so many good chips, not everybody is doing it with a microprocessor! I still do a lot with 4000 series CMOS but it is getting harder with chips being dropped all the time.

If you are using a full bridge rectifier you will need to divide by 120. Two 74-90 or 74-93 will do this easily.

I found a listing at e-Bay for the MC14566, for some reason a check for the CD4566 didn't show any results. They had 7 chips available at $1.29 each.

Hi Wiz,

Thanks for all the effort. I'll take a look at the data sheet and decide.

-S

Back in 1980 I wrote a clock program for an 8080 chip, used on a trainer.

You write machine language instruction loops of the correct execution time and do jumps to the instruction to get the loops and then write the forward, backward necessary to set the "time" you want on the clock display.

I then debated if I should do video game software or go start power plants. The power plants appeared to be more remunerative at the time, now with the quantity of computers for games to run on, there are people making a fortune writing games.

Hi Andy,

I don't plan to get that system, at least not now. I think my son has the Arduino board, but doesn't know how to use it. I don't either, so information about that would be more useful. I'll keep you in mind, thanks.

Errr- I just re-read your post. Are you saying that I don't need a microprocessor board, just my computer with a free program and a USB port? The chip is a programmable logic and just wires up to a USB connector? You're peaking my interest.

-S

YUP!!

Its even cheaper to set up than the Arduino chips are.....

Both are very similar to each other in there usage......shame your son cannot program the Arduino, it would also do the job for you.....

Next week, I will see if I can write the same program for the Arduino, if the software is free and easy to understand.....

I cannot find a free simulator for Arduino, so as I do not have the hardware, I cannot test the program, but should be easy fo your son to convert my program into Arduino Basic code......

I found this website that will maybe explain things better than I can:-

http://www.pldesignline.com/blogs/212901825

Here's another one, even better I feel:-

http://dave.fraildream.net/picaxe/index.shtml

That halo might get to be a problem

You get used to it quickly and the envy from others......no problem for me either way....