Sycnhronous Counter for Mux

Thread Starter


Joined May 19, 2020
I need a simple circuit for controlling an analog Multiplexer. The first part is a basic synchronous counter that can count up to 2 (00, 01, 10, then back to 00) which is controlled by a tactile switch, the 2nd part is a digital mux that is used to indicate which number the counter is on via 3 LEDs, and the 3rd part is an analog mux which is also controlled by the counter. I could do this with a pair of schmitt triggers (one to condition the pulse generated by the tactile switch, and the other to reset the counter to 00 when power is turned on), a dual JK flip flop for the counter, an AND gate to reset the flip flop when it counts to 11, a 4052 mux for the LEDs, and finally a DG409 for the analog multiplexer. It seems overly complicated though. Is there a simpler way to do this? Maybe a simple PIC? The DG409 is the only non-negotiable component.


Joined Sep 17, 2013
Yeah I dunno about your "debounce circuit", this isn't usually enough, I would probably have opted for MAX6816 (single)/MAX6817 (double) (yeah they've been around awhile), these tactiles can get noisy. That's not what you're asking about though. Since you have exactly 4 LEDs and 4 states you don't need the 4052, just connect each LED across two different outputs of the flipflops. PICs aren't likely to save you much since it looks like you need at least to mux a bipolar (below ground) analog signal, the PIC can get you either 10 or 12 bits but only between at most +5 and ground. Some of the PICs have internal opamps, comparators or gate array functions too but those fucntions tend to get lost in "pin assignment hell" at least if you're trying to use a high percentage of chip function. The PICs tend to offer more value if you can do input, processing AND control all on-chip.