The basic digital circuits are Flip Flop and Counter, both are here. This circuit can be cascaded to make even a 6 digit event counter, even a simple frequency counter can be made.
Digital Timers, Counters and Clocks
These are best done with microcontrollers today. Then what if you have to design your own microcontroller on a FPGA, so the basics have to be sound, hence you have to know what gates, flip flops and counters are.
Read more »