CD4029B: Best IC for presettable up/down counter for use with 7-segment display

Hi Kirsten and welcome to the forums!
Typically these days the best solution is to use a microcontroller -- there are a lot of low cost, low power options out there that are basically infinitely customizable. I recently did a similar build with an MSP430FR2311. The one down side is that you have to program an MCU, and for mass production that adds cost and complexity. In this case though -- for a one-time build -- it's probably your best bet. The code is likely going to be very simple.

I know that doesn't directly answer your question though. If you're intent on using logic, I want to get some clarification on the requirements.

The CD4k family of logic is pretty old and generally inefficient for modern designs. Because it's old, it also includes functions that are typically handled by MCUs today - like counters. Most of our customers only choose CD4k logic if they need an obscure function, or if they really need to operate between 5V and 18V. HC is similarly old (it was the original CMOS replacement for SN7400 series TTL logic)

Can you tell me a bit about the requirements for your system? Are there power constraints? Voltage? What kind of signal is coming in? What kind of load is to be driven? A block diagram would be helpful if you have one -- preferably with a lot of detail around the signals in and out of the counter.

Hi Emrys,

Thanks so much for your response!

Unfortunately, this is for a university project and we are not allowed to use microcontrollers! You were spot-on with my voltage limitations though, as the power supply to the system has to stay within the 3V to 18V range.

Besides the voltage constraints, the signal being received is from a transmissive optical sensor with phototransistor output (TCST110-230). I was planning on designing a circuit which passes a voltage pulse that is generated by the gap sensor through a 555 timer and then to the 4029 (one gap sensor will count down, another will count up), which will generate an output via a 7-segment display.

I didn't mention the second part of the circuit functionality because I haven't explored it yet, but perhaps it will be useful to you - my system (which is just made up of tracking the number of cars entering and exiting the parking lot) has to be able to generate a signal that shuts off various other subsystems when the parking lot reaches its maximum or minimum capacity - it has to switch off a fan and lights when the parking lot is empty, and it has to disable a boom motor when the parking lot is at maximum capacity. The fan system will be implemented using a Schmitt trigger circuit, and the lighting system will be implemented using an analogue comparator circuit.

I'm not in charge of all the subsystems for this project, but I'm meeting with the other group members tomorrow and will be able to get more information, including a block diagram showing how all the subsystems interact.

Thanks again for your feedback!