counterdigital-logicintegrated-circuit
I've been connected pins input A and C into VCC so the logical number is 1 and input B and input D with 0. The counter starts with 5, but it doesn't clock or change from number 5 into 0 (5,4,3,2,1,0,5,4,3,2,1,0) as I need.
What should I do for this 74190 so it will count down from 5 into 0 and so on?
The MM5450 may do what you want.
34 outputs, serial fed, chainable.
Notionally 3 pins to drive (clock, data, latch) but can be driven with 1 pin if needed. Digikey $4.39/1 This one in DIP-40 but also available in LCC.
if this does not suit your need you need to provide a more complete description of your requirement.
Outputs are open drain, ie either on = low or off = float or open circuit.
The key points are:
Ensure that after gating the new arrangement makes logical sense. ie why should it count DOWN now. If you don't follow the logic of what you think it should do then you can't be too surprised if it disagrees with you :-)
Always change over in a "neutral" state. Ensure that clock lines or other state relevant lines are in a condition before and after the change that will not cause a transient change of state.
A marvellous (& free) tool
Logisim - an educational tool for designing and simulating digital logic circuits
They say:
Best Answer
You have to load the number and then stop loading and start counting down. Thus check the sequence of the load(not), CTEN(not) and clock pins.
First load low
Then load high
Then CTEN low
Then clocks
Also make sure D/U is high.
By the way, all that is in the datasheet: