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+# Multiple Micro-controller Homing and Probing
+
+Klipper supports a mechanism for homing with an endstop attached to
+one micro-controller while its stepper motors are on a different
+micro-controller. This support is referred to as "multi-mcu
+homing". This feature is also used when a Z probe is on a different
+micro-controller than the Z stepper motors.
+
+This feature can be useful to simplify wiring, as it may be more
+convenient to attach an endstop or probe to a closer micro-controller.
+However, using this feature may result in "overshoot" of the stepper
+motors during homing and probing operations.
+
+The overshoot occurs due to possible message transmission delays
+between the micro-controller monitoring the endstop and the
+micro-controllers moving the stepper motors. The Klipper code is
+designed to limit this delay to no more than 25ms. (When multi-mcu
+homing is activated, the micro-controllers send periodic status
+messages and check that corresponding status messages are received
+within 25ms.)
+
+So, for example, if homing at 10mm/s then it is possible for an
+overshoot of up to 0.250mm (10mm/s * .025s == 0.250mm). Care should be
+taken when configuring multi-mcu homing to account for this type of
+overshoot. Using slower homing or probing speeds can reduce the
+overshoot.
+
+Stepper motor overshoot should not adversely impact the precision of
+the homing and probing procedure. The Klipper code will detect the
+overshoot and account for it in its calculations. However, it is
+important that the hardware design is capable of handling overshoot
+without causing damage to the machine.
+
+Should Klipper detect a communication issue between micro-controllers
+during multi-mcu homing then it will raise a "Communication timeout
+during homing" error.
+
+Note that an axis with multiple steppers (eg, `stepper_z` and
+`stepper_z1`) need to be on the same micro-controller in order to use
+multi-mcu homing. For example, if an endstop is on a separate
+micro-controller from `stepper_z` then `stepper_z1` must be on the
+same micro-controller as `stepper_z`.