Add support for active-high limit switches

config.h

@@ -171,6 +171,12 @@
 // successful values for certain setups have ranged from 10 to 20us.
 // #define STEP_PULSE_DELAY 10 // Step pulse delay in microseconds. Default disabled.
 
+// Uncomment the following define if you are using hardware that drives high when your limits
+// are reached. You will need to ensure that you have appropriate pull-down resistors on the
+// limit switch input pins, or that your hardware drives the pins low when they are open (non-
+// triggered).
+// #define LIMIT_SWITCHES_ACTIVE_HIGH
+
 // ---------------------------------------------------------------------------------------
 
 // TODO: Install compile-time option to send numeric status codes rather than strings.