I'm trying to build a 0 to 999Hz frequency counter in Multisim that will output the value of an external frequency and hold the value, but I'm having trouble getting it to work.

The block diagram is as follows and is within the red perimeter:


The circuit I built in Multisim:



From the above circuit it doesn't output the 120 Hz input frequency to the display. I even tried leaving the simulation running for almost an hour to see it count to 112 in Multisim, after which I'm guessing Multisim stopped running the simulation.

 

The way to troubleshoot this is to test one function at a time.

Test the counters U2, U4, U8 with a 1Hz CLOCK input and hold LD at logic HIGH on the 4543 Latch/decoders U11, U12, U13.

 

The way to troubleshoot this is to test one function at a time.

Test the counters U2, U4, U8 with a 1Hz CLOCK input and hold LD at logic HIGH on the 4543 Latch/decoders U11, U12, U13.

I tried what you suggested and the display reads 000 and doesn't appear to change at all.



Setting Clock Input to GND:

Setting PE to GND produces 999 on the display:

 

What type of displays are you using?
If the display module is LCD then you need to connect the PHASE signal to the BACK PLANE.
If the display is LED then you need current limiting resistors (about 220Ω) on each of the seven segments.

 

Your just wanting to have this running in simulation ?
What level of home work is this for ?

 

What type of displays are you using?
If the display module is LCD then you need to connect the PHASE signal to the BACK PLANE.
If the display is LED then you need current limiting resistors (about 220Ω) on each of the seven segments.

The display is an LCD but I haven't built it in hardware as it doesn't work in Multisim. It should output the 120Hz frequency but it doesn't.

 

I tried what you suggested and the display reads 000 and doesn't appear to change at all.

View attachment 281626

Setting Clock Input to GND:
View attachment 281627
Setting PE to GND produces 999 on the display:
View attachment 281628

If you download the Intersil datasheet, and wire it up for "parallel clocking" as per figure 13, you should find it works as required.

 

If you download the Intersil datasheet, and wire it up for "parallel clocking" as per figure 13, you should find it works as required.

Trying that the output stays at 000:

 

I do not use Multisim. I tested the 4029 and 4543 on another simulator and they work.

 

Trying that the output stays at 000:
View attachment 281635

Triggering the PE inputs High will always transfer whatever is on the P0 to P3 inputs to their respective outputs, regardless of anything else. You need to connect them to 0V! So disconnect U9A output from them and connect them to 0V, or re-design your circuit for the (reset?) function you expect.

 

Triggering the PE inputs High will always transfer whatever is on the P0 to P3 inputs to their respective outputs, regardless of anything else. You need to connect them to 0V! So disconnect U9A output from them and connect them to 0V, or re-design your circuit for the (reset?) function you expect.

I'm expecting the circuit to display the input frequency of any number from 0 to 999Hz. I've set the PE inputs to 0 and it now displays 099 instead of the 200:

 

I do not use Multisim. I tested the 4029 and 4543 on another simulator and they work.

If you want to try it in Multisim I can send you the file. You can get a free 45 day trial at https://www.ni.com/en-us/support/downloads/software-products/download.multisim.html#452133

 

I'm expecting the circuit to display the input frequency of any number from 0 to 999Hz. I've set the PE inputs to 0 and it now displays 099 instead of the 200:
View attachment 281665

Is that with the complete circuit above being used? Because it seems to me that if if U10A is getting a 0.5Hz input signal on one side, then your counters are only going to count for 100 counts, + or - one count, just as you are seeing!
Unless you're using a crystal on the CD4060 U1, you don't need R1, R2, C1 and C2, you can just drive it from U5, whatever that is.

 

Hi,
How did you get on with your circuit? A quick reply would be helpful to let us know whether your problem was solved to your satisfaction, and ours. It's always nice to hear back from the TS.

Regards.

 

Is that with the complete circuit above being used? Because it seems to me that if if U10A is getting a 0.5Hz input signal on one side, then your counters are only going to count for 100 counts, + or - one count, just as you are seeing!
Unless you're using a crystal on the CD4060 U1, you don't need R1, R2, C1 and C2, you can just drive it from U5, whatever that is.

Exactly! I was wondering how come nobody hadn’t noticed that the clocking circuit is incorrect. The TS is using the clock biasing scheme used on a tuning fork resonator. If an external 32.768k clock is used, it should go straight to the clock input pin.

 

There is a bug in Multisim where if you use the 32.768Khz crystal the output goes into the MHz range, which is why I was using the digital signal generator instead. I now have it going directly into the clock input. However I can't figure out the control circuitry from the block diagram which has a line labeled "Load" going into the Latch Disable (LD) of the 4543 and the Reset going to the Preload of the CD4029. So far I have been unable to get it to hold the display value or reset with the switch. .