Probe Basic and Carousel ATC with Geneva and Stepper

Hi, i've build a gantry piggy back toolchanger for my router, driven by a stepper (with gear reduction) and a geneva wheel, and am looking for some quick pointers.

At this point I've got it to rotate, creating an extra axis in HAL / INI, nothing else.

I was planning to use the stepper 'velocity mode' to drive the stepper.
I envision I need to place two proximity sensors:

1. Prox sensor for homing pin
2. Prox sensor to detect an index step, for counting logic of the pockets
   
   How does the base Probe Basic configuration handle pocket homing (locating pocket nr 1), counting pockets and the drive signals to the motor?
   
   Some clips of the geneva mechanism:
   
   
   
   
   
   
   
    
   

I think I already found most of what I was looking for, as I just found:
github.com/kcjengr/probe_basic/blob/main...toolchange_index.hal :-))

Still have to find out the best approach to map the stepper drive signal in velocity mode to
net car-ccw motion.digital-out-03
net car-cw motion.digital-out-04
 

In order to control the ATC stepper motor like a "dumb DC motor" with just the DI-Outputs mapped to my MESA outputs and free up the stepgen on the MESA for other future purposes, I simply purchased a step generator from amazon (10 bucks) and two relays.

I will just use the relays to trigger the board start/ stop and direction tactile buttons (solder to button pins).
Should work fine in combination with the geneva drive..

I still have to find good sensor flag positions for Home and Index, but that should be solvable.

 

 

About the Index sensor - Pocket sensor vs drive wheel sensor
This could be a design issue, but if I look at my geneva mechanism I think for indexing ideally you would want to detect the pin on the geneva drive wheel, so the drive wheel is fully locked in the geneva wheel.

If you detect just a pocket pin, the drive motor and drive pin will stop at the disengagement position of the pin, where the lobe takes over.
 

If I detect the drive pin on the drive wheel, it would allow for more error margin as the lobe is fully engaged.
But this would require both the index sensor and homing sensor to be high to complete initial homing.
Otherwise the first index move after homing could be false, depending on the direction.
 

What is the usual way to do this?
If I check the subroutines the M13 homing cycle is not considering the index sensor, only the homing sensor.

Maybe bind Index sensor to the Homing sensor input signal in HAL using AND2 ?

Detecting the drive pin could also cause par tracking issues if an anomaly happens.

Maybe detecting pocket pins on each index and a homing pin is better.
And just make the motor stop with a slight delay, so the geneva drive fully engages.

By e.g using M65 P4 Qxx in subroutines.