I want to control the spindle on/off via a relay using the spindle enable pin with M3 and M5. (I am not controlling speed using pwm). I understand that GRBL 0.9 changed the pinout to allow PWM speed control. I am using GRBL 0.9j. If I comment out the #define VARIABLE_SPINDLE line in config.h, the output appears as expected on D12. However M3 only switches D12 HIGH if I have previously set S to some value other than zero. I expected the 'S' setting to be irrelevant if VARIABLE_SPINDLE is not defined. The S value doesn't persist and always resets to zero (presumably a safety feature) so I need to send S1 after every reset to allow motor control. Is it possible to change this behaviour or set S to default to a non-zero value? I have tried several compile-time options in config.h but am reluctant to change the main code with my limited knowledge.