A long time ago I saw a small logic probe, with TTL/CMOS level indication (Red/Yellow/Green) and a four LEDs counter for the frequency of the signal. Somewhat later I created two separate tools, one TTL-level indicator and the pulse counter described here. Recently I made a board for it. But having this, there are plans to expand it somewhat:
- selectable up/down/both flank count,
- more LEDs and/or spread them over a wider range in triplets,
- make it more compact with SMD parts,
- integrate the TTL/CMOS level indicator.

The levelLogicProbe is here: https://electrickery.nl/digaud/tools/levelLogicProbe/