Very simple binary counter

[sushi4664]

binary counter

I need to make a very simple binary counter. It will behave somewhat like a binary clock with two separate counters. So the first one would trigger the next.

I was thinking of using two 74HC590's and some four input AND gates to make it. The idea behind it would be that there would a clock source for the first 590, which would start counting. Once it would reach 60 (4+8+16+32) - for 60 seconds - it would then trigger the four input AND gate to send a signal to the second 590, which would then receive clock signals in one minute intervals.

My question are the following:

I used the 74HC590 because it is synchronous. Originally I was planning on using 4020's. Because this circuit is supposed to be precise I decided to switch over to the 590. Would a ripple counter truly affect the preciseness?

The 74HC590 says the reset is active low. What does that mean? Does that imply that for normal operation there needs to be a voltage source on its reset pin?

Thanks in advance for any help!

-sushi

 

[rwiggins]

flip flop binary counter

To your first question, you should be able to use a ripple counter. To your second question, it means that the pin should normally be held high until you want to activate it by pulling it low. Hope it helps!

 

[Srikant Rao]

simple binary counter

Reset low implies that it gets activated when it has a low voltage flowing through that pin.
A ripple counter is asynchronous so it would not be as precise as a synchronous one.
But a ripple counter would be way easier ...
Hope that helps ...

 

[sushi4664]

ripple counter with reset

Ok, I understand the reset concept.

I am still shaky on the ripple counter. My worry is (and of course this could be completely off...as I am new to electronics) that if the states of the flip-flops don't change at the same time, there would be a delay in the AND or NAND gate thus causing the second counter to get delayed a little by little every clock cycle...thus making a huge difference over a period of time.

I have been searching for a 7/8 bit synchronous binary counter online, but have unable to find anything. I guess, my only other option would be to hook two 4 bit synchronous binary counters together...which I have no idea how to do. Any ideas/pointer on that would be superawesome.

 

[rwiggins]

binary counter problem

why not breadboard it and see?

 

[sushi4664]

making binary counter

I think thats what I am going to end up doing. I wanted to get people's inputs before I did because I would have to buy parts and money is in short supply *high schoolers don't make much *...but yea...

My gut is telling me that since the clock speed is at 1Hz, the time it should take to switch all the flip-flops shouldn't matter because the would be done before the next pulse arrives.

 

[xulfee]

synchronous one shot counter circuit

active low means when we apply zero to its reset pin,counter will reset,synchronous is some thing other ICs are not synchronous as wht i think,synchronous or asynchronous is basically the configuration in which ICs r connected to make counter.

 

[Kral]

making a binary counter electronics

sushi4664,
There are two issues that you must deal with. Even with a synchronous counter, the individual outputs are not guaranteed to switch at exactly the same time. As a result, you face the danger of getting false pulses from the output of the and gate when the counter is changing states. A safe way of dealing with this problem is to decode "59" instead of "60". feed the output of the gate to the input of a D flip-flop. Then, on the next clock pulse, the counter outputs will have stabilized, and the flip flop will change state on the count of 60. Use the output of the flip-flop to trigger the next counter.
.
The other issue you must deal with is resetting the first counter to zero after the count reaches "60". You can't simply feed the flip-flop output the the MRC input, because the MRC input is asynchronous, so the counter would never come out of the reset state. One way to handle this problem is to feed the output of the flip flop to a "one-shot" whose output pulse width is less than the clock period. Connect the "one-shot" output to the MRC input. The same reset problem occurs with the second stage also.
.
Regards,
Kral

 

[laktronics]

binary counter dff

Hi,
You can use ripple counter for this application without any problem. As you have rightly told the one sec duration is long enough for any rippling effect to settle.

Also you will not get any multiple pulses for the highest decoded output in a ripple counter, as this state can be entered only once in the counting loop.

If you use BCD counters, you only have to decode for digit 6 at the output of the 10's counters of seconds and minutes to generate reset pulse as well as the input pulse to the next chain of counters.

As Kral has mentioned, use a monoshot after decoders to generate proper pulses for reset as well as for next stage input. In my opinion, the monoshot is required to avoid partial reset rather than getting stuck with permanent reset.

Regards,
Laktronics

 

[Kral]

simple binary counter

sushi4664,
Regarding your 1st post; You need not be concerned about the cumulative delay of a ripple counter, until the cumulative delay reaches 1 second, the period of your clock. This would not occur unless you had a huge number of stages.
.
Regarding laktronics’ second statement, take the example of a simple 2 stage binary counter:
. State 0 00
. State 1 01
. State 2 10
. State 3 11
Suppose you are decoding the highest count (11). If, in going from state 1 (01) to state 2 (10), bit 1 (the MSB) is slightly faster than bit 0 (the LSB). The counter would momentarily go to state 3 (11) before it went to its equilibrium state 2 (10). This would result in the decoder momentarily seeing state 3 (11) and producing a short “trash pulse”. Whether this does any harm or not depends on whether the stage that is being clocked by the decoder AND gate is fast enough to respond to the short “trash pulse”. This problem is insidious because, according to Murphy’s law, it will not show up in the breadboard and prototype units; only in the 100th or so production unit 
Regards,
Kral

Added after 1 hours 10 minutes:

sushi4664,
After re-reading my last post I realized that laktronics is correct regarding a ripple counter. It is only with a synchronous counter such as the 74HC590 that the race problem can occur. In a ripple counter a higher order bit can not possibly change state before the next lower order bit changes state.
Regards,
Kral

 

[sushi4664]

how does a 8 bit binary counter work

What is a monoshot? I think I understand the purpose, but still have no clue how I go about making/getting one.

 

[laktronics]

how binary ripple counter and nand gate work

Hi,

Monoshot is a circuit which produces one pulse output for a zero to one OR one to zero transition at its input. Google and read about highly popular monoshot IC NE555 and its applications for more information.

Regards,
Laktronics

 

[sushi4664]

binary counter in microcontroller

Thank you sooo much!

I will google that and probably order the parts pretty soon from mouser....

...one final question/opinion...after considering this circuit...i just realized how easy it would be to make it using a microcontroller, which i am quite familiar with....

but, obviously constructing it out of logic chips will, in the end, leave me more satisfied...

I am just wondering, which do you *all of you* think I should do? Microcontroller? Or Logic?

 

[nandhu015]

electronics binary counter 10

I prefer a microcontroller which would be cheap and the whole thing will be done in a single chip.

Nandhu

 

[laktronics]

simple second counters

Hi,
Your posts so far did not reveal that you know microprocessors, and obviously as Nandu has mentioned , hardwarewise, it will be the most compact solution and that is the way you should do it.

Regards,
Laktronics

 

[Kral]

binary ripple counter many topic

The common names for this device are:
. One-Shot
. Monostable Multivibrator
It is a device that, when triggered by an external pulse, produces a single output pulse of a duration determined (usually) by external components. Most One-shots produce a pulse with a predefined width if no external components are connected. See for example,
. en.wikipedia.org/wiki/Multivibrator
. www.fairchildsemi.com/an/AN/AN-138.pdf
. www.visionics.ee/curriculum/Experiments/555 Monostable/555 Monostable1.html
Regards,
Kral

 

[Siniša]

binary counter, clock pulses

You mentioned that it has to be precise, but you did not quantify it. Also you did not elaborate what you plan on using for clock source, since "precision" is required.
MCU is obviously logical choise. If "precision" is in sub µsec range, than it might require some work on µcu program to get it as close as possible. If you are talking of msec range than obviously that µcu is absolute winner.

If you would like to learn using standard logic circuits, this would be very good project to work on. So there you go. If you want fast solution, µcu and if you want to learn, not µcu.