How do I calibrate impulse detection on a table mount?

The issue you're running into is classic noise floor detection becuase wood desks are great for resonance. If you're getting false triggers from typing, the problem isn't just the sensitivity threshold; it's that the ambient noise profile overlaps with your tap signature. Instead of just trying to adjust the raw sensitivity of the accelerometer, try applying a low-pass filter to the data stream before it hits your decision logic. A simple digital low-pass filter can significantly smooth out those tiny, high-frequency vibrations caused by keyboard clicks or footsteps, letting only the heavier, slower motion of a deliberate tap through to the processing stage. If you're using an MPU6050, you can implement a basic complementary filter, which actually mixes the accelerometer and gyroscope data. The accelerometer is good for hard shoves, but the gyroscope provides consistent data even during momentary impacts, which can help stabilize the readings and make the recognition much more reliable than using just one axis. Regarding the debounce time, it's not just about preventing one tap from registering as two. You should implement a time window check. For instance, after a successful trigger detection, hold the system in a cooldown state for about 500 milliseconds. This prevents the system from reacting to residual vibrations caused by the initial tap's impact. If you see multiple triggers within that 500ms window, you know they are likely just aftershocks of the first event rather than a distinct double tap. For the advanced filtering you mentioned, a Kalman filter is definitly overkill unless you are trying to acheive military-grade precision, but the math behind it helps isolate true movement by predicting where the sensor should be and comparing that prediction to the actual input. If your ESP32 has enought processing power, that method should drastically cut down on the false positives you are seeing.

I was looking over your advice about the filters and the timing logic. It sounds like a lot of complex math to get right. I was thinking more about where I stuck the sensor, because maybe the way it is mounted is the problem, not the code. I just screwed it directly into the wood of my desk surface. If I put it on a piece of rubber or somthing soft, do you think that would help the sensor ignore the small shakes coming from my keyboard typing? I just wanted to know if the physical mounting setup changes the readings at all.

I totally agree with the point about changing the mounting setup. The vibration travel through the desk surface is definitely a major source of noise. My solution ended up being similar to using a soft barrier but with a slight twist. I didn't just put the sensor on a pad, I mounted the entire ESP32 unit inside a small, dense silicone housing. This totally absorbed the high frequency energy and stopped the casing itself from ringing when I tapped the desk. It made the triggers way more consistent.

You need to check your sampling frequency, because adjusting sensitivity won't fix the underlying data loss. If you're running the sensor at the default rate, you're likely missing the actual peak of the tap event entirely. I ran into the same resonance problem setting up my desk monitor control, and I forced the IMU to sample at 1000 Hz. This really helped me capture the transient spike cleanly, wich meant the required threshold for activation was much more predictable.

I ran into a bit of this while messing with something similar. Instead of just obsessing over the sensitivity threshold, i started focusing on the timing between the events. Even if the accelerometer registers a bump, if the interval before the next expected spike is way too long or too short, i just ignore it. I implemented a simple state machine to track the sequence. This helped me distinguish a deliberate double tap from just two random background vibrations that might have passed the initial trigger check. It makes the code a bit messier, but it really solves the consistency problem.