diff --git a/klippy/klippy.py b/klippy/klippy.py
index 6668ef4c..ecf5da44 100644
--- a/klippy/klippy.py
+++ b/klippy/klippy.py
@@ -79,10 +79,6 @@ class Printer:
         self.build_config()
         self.stats_timer = self.reactor.register_timer(
             self.stats, self.reactor.NOW)
-    def connect_debug(self, debugoutput):
-        self.mcu = mcu.DummyMCU(debugoutput)
-        self.mcu.connect()
-        self.build_config()
     def connect_file(self, output, dictionary):
         self.mcu = mcu.MCU(self, ConfigWrapper(self, 'mcu'))
         self.mcu.connect_file(output, dictionary)
diff --git a/klippy/mcu.py b/klippy/mcu.py
index 070bc7d2..de9518ac 100644
--- a/klippy/mcu.py
+++ b/klippy/mcu.py
@@ -458,90 +458,3 @@ class MCU:
         mcu_time = print_time + self._print_start_time
         clock = int(mcu_time * self._mcu_freq)
         self.ffi_lib.steppersync_flush(self._steppersync, clock)
-
-
-######################################################################
-# MCU Unit testing
-######################################################################
-
-class Dummy_MCU_stepper:
-    def __init__(self, mcu, stepid):
-        self._mcu = mcu
-        self._stepid = stepid
-        self._sdir = None
-    def queue_step(self, interval, count, add, clock):
-        dirstr = countstr = addstr = ""
-        if self._sdir is not None:
-            dirstr = "D%d" % (self._sdir+1,)
-            self._sdir = None
-        if count != 1:
-            countstr = "C%d" % (count,)
-        if add:
-            addstr = "A%d" % (add,)
-        self._mcu.outfile.write("G5S%d%s%s%sT%d\n" % (
-            self._stepid, dirstr, countstr, addstr, interval))
-    def set_next_step_dir(self, dir):
-        self._sdir = dir
-    def reset_step_clock(self, clock):
-        self._mcu.outfile.write("G6S%dT%d\n" % (self._stepid, clock))
-    def print_to_mcu_time(self, print_time):
-        return self._mcu.print_to_mcu_time(print_time)
-
-class Dummy_MCU_obj:
-    def __init__(self, mcu):
-        self._mcu = mcu
-    def home(self, clock, rest_ticks):
-        pass
-    def is_homing(self):
-        return False
-    def home_finalize(self):
-        pass
-    def set_pwm(self, mcu_time, value):
-        pass
-    def set_minmax(self, sample_time, sample_count, minval=None, maxval=None):
-        pass
-    def query_analog_in(self, report_time):
-        pass
-    def set_adc_callback(self, cb):
-        pass
-    def print_to_mcu_time(self, print_time):
-        return self._mcu.print_to_mcu_time(print_time)
-
-class DummyMCU:
-    def __init__(self, outfile):
-        self.outfile = outfile
-        self._stepid = -1
-        self._print_start_time = 0.
-        self._mcu_freq = 16000000.
-        logging.debug('Translated by klippy')
-    def connect(self):
-        pass
-    def disconnect(self):
-        pass
-    def stats(self, eventtime):
-        return ""
-    def force_shutdown(self):
-        pass
-    def build_config(self):
-        pass
-    def create_stepper(self, step_pin, dir_pin, min_stop_interval, max_error):
-        self._stepid += 1
-        return Dummy_MCU_stepper(self, self._stepid)
-    def create_endstop(self, pin, stepper):
-        return Dummy_MCU_obj(self)
-    def create_digital_out(self, pin, max_duration=2.):
-        return None
-    def create_pwm(self, pin, hard_cycle_ticks, max_duration=2.):
-        return Dummy_MCU_obj(self)
-    def create_adc(self, pin):
-        return Dummy_MCU_obj(self)
-    def set_print_start_time(self, eventtime):
-        pass
-    def get_print_buffer_time(self, eventtime, last_move_end):
-        return 0.250
-    def print_to_mcu_time(self, print_time):
-        return print_time + self._print_start_time
-    def get_mcu_freq(self):
-        return self._mcu_freq
-    def flush_moves(self, print_time):
-        pass