I'm trying to make a counter that counts down from 9 to 4 (9-8-7-6-5-4) then returns to 9 and so on. I managed to set the max to 9 but I don't know how to use the TC pin (pint 12) to set the minimum. Can anybody guide me on how to use the TC pin?

 

Welcome to AAC!

Post a schematic for your circuit and show what you've tried that didn't work.

 

Welcome to AAC!

Post a schematic for your circuit and show what you've tried that didn't work.

It's not that I tried something that doesn't work, I don't know what to do with the TC pin it's supposed to control the max/mix values right?

 

I don't know what to do with the TC pin it's supposed to control the max/mix values right?

Have you read the datasheet?

You're using a binary counter, so the min/max count output isn't useful for your problem.

Is this school work?

 

TTL logic is 58 years old. I used it 56 years ago. I stopped using antique TTL 42 years ago and used Cmos logic ever since.

 

It's not that I tried something that doesn't work

Didn't Proteus flag the two outputs that you have shorted together?

 

TC indicates that the counter has all ones in the four stages. It is not relevant to your problem. In order to count down the D/U-bar pin must be tied high (to LOGIC 1) and you must load the value on the D-input when the output = 4

 

Why is U7 an OR gate?

ak

 

Why is U7 an OR gate?

ak

01xx OR x100 makes perfect sense in some alternate universe.

 

It's not that I tried something that doesn't work, I don't know what to do with the TC pin it's supposed to control the max/mix values right?

1. On startup:
Preload 9
2. When count reaches 3 and clk is high:
Preload 9 again
3. goto step 2