Minimum Stepper Speed w/BlackBox X32

I am trying to achieve stepper speeds between 1 and 100 mm/hour using the BlackBox 32 and a nema23 stepper motor. I contacted open builds and they suggested I may be able to achieve this using custom firmware. Looking on the grbl git I see the grbl firmware for an Arduino Uno. In the config.h file there are some definitions that look like they would allow me to enter speeds slower than the current minimum of 1mm/min. Referring to the #define N_DECIMAL_RATEVALUE_MM which is normally set to 0. I think I can set this to 4, enter my desired speed, and be off to the... races... so to speak.

Now I'm looking for the grbl firmware for the BlackBox 32. I think I found it here but was hoping someone could a) confirm that this is where I get the most recent firmware for the BlackBox X32, and b) confirm my idea for changing the minimum speed and/or point me in the right direction for reducing the minimum speed limitation for the stepper motors.

 

Thank you Peter van der Walt. I decided to try the custom firmware route today before switching to Arduino and DQ542MA. I was able to build the version of the firmware in the GitHub - grblHAL/ESP32: grblHAL driver for ESP32 repo but when I flash it to the controller I get repeated errors seen below:

Any thoughts on what may have caused this? Only thing I changed was the MINIMUM_FEED_RATE 0.001f in the config.h file.

 

II was able to recover using the wizard but I would still like to adjust the MINIMUM_FEED_RATE to 0.001f in the config.h file. Is there some way to do this without rebuilding the grblHAL project? Is there some obvious setup step that I may be missing when building the project?