Optical Flow using 3901 UART and Pixhawk Clone ( 2.4.8)

I was using the following link as a guide to install optical flow on my drone and already have a Sonar installed that is reporting altitude.


I ordered and connected the ThoneFlow 3901U sensor as it looked to be the most economical choice to test it out.

Mission Planner reports value spikes of +1, -2 etc in opt x and y when I have my arm close to sensor and wave but it is inconsistent.

Does this sensor require a lens to work correctly? Can anyone if they have a working setup show me what values to expect since this sensor does not show video output like the PX4Flow to calibrate.

How do can I test this out without flying the drone to have at least an approximation that I am getting correct readings.

Example: To test the range sensor, I can just lift the drone and see the change in values. The opt x and y here don’t show any change if I move the drone.

I think I got it work. Or rather was testing incorrectly.
The optical flow sensor was too close to the ground.
Due to the fixed nature of the lens and lack of additional magnification/reduction, a clearance of at least 300mm was required before I could see the movements being recorded in optical flow

Excuse me
How to connect this module to Pixhawk
and how can I let this module work ?
p.s. I already have an drone can fly at AltHold mode properly(with sonar)