This is the improved Quad Stall Motor Controller w/ point Sense "hat" for the  

Raspberry  Pi. It uses  TC4428's to drive the Stall Motors and uses 

SN74AHC00N's wired as RS FlipFlops to debounce the point sense (assumes a SPDT 

switch mechanically connected to the points (or the internal switch in the 

Stall Motor). Uses 8 GPIO pins:                                               

BCM17 Motor 1                                                                  

BCM18 Motor 2                                                                  

BCM27 Points 1                                                                 

BCM22 Points 2                                                                 

BCM23 Motor 3                                                                  

BCM24 Motor 4                                                                  

BCM25 Points 3                                                                 

BCM4 Points 4

GitHub Projecct:                                                               

https://github.com/RobertPHeller/RPi-RRCircuits/tree/master/QuadSMCSenseHat    

Mouser Project (parts):                                                        

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=330542c522   

OpenMRN program: QuadSMCSenseOpenMRN, on GitHub at:

https://github.com/RobertPHeller/RPi-RRCircuits/tree/master/QuadSMCSenseOpenMRN