Now for the software, I am using some of the pieces of old software but most must be rewritten. For example using floating point to represent voltage in Arduino (?!) is total waist. 

The next step are just like the first steps in moon landing.

First step, lets make a 'hard landing' - we will run full range sinus and look how frequency will change. We don't use quartz fork  with probe but the simple quartz fork. We don't mind banging the quartz fork.

Second step, soft landing we will lower the quartz fork gently until it reach the bottom. Once it stops we can go up and down and see if this consistant.

Third step, scannig of the sample

Well the first step includes building my own software plus libraries for example AD5696 DAC library from Analog Devices. 

I took me two days to figure out why it's not working. I changed the address bits in hardware but forgot to upade GIT about. 

Now I got the ability to get quartz fork/probe up and down with resolution of 16bit. 

Now let's setup the frequency generator AD9833 and try to hit the surface qnd and see what happens. 

FIRST TEST - Using coarse movement mechanism I managed to lover the QFM less than millimeter from surface. This mechanism is basically a screws with springs they able to lower the QFM board along with QF (quartz fork) on it. The intermediate movement is more complex, it OpenFlexture delta stage with ability to move in XYZ with resolution of about micrometer. 

So first thing was just to 'crush' QFM into the delta stage that is right underneath quartz fork. As a result PLL output went from stable 180/5500 to 2000/5500

This cheap 10$ long distance microscope shows every upsidedown. 

Next test is to bring the quartz fork close and use piezoelectric (fine movement) to gently touch. 

We can see how both PLL output and frequency changes as a result. 

To conclusion, now we were able to crush into the samle holder and manually soft landing. 

The next step will be fully automatic soft landing. 

Yoohoo! Was able to land softly!!! 🎯