diff --git a/templates/bluepill/test b/templates/bluepill/test
index 1761449..d4665d7 100755
--- a/templates/bluepill/test
+++ b/templates/bluepill/test
@@ -142,9 +142,6 @@ def main(argv):
     finally:
         tool.end_measurement()
 
-    sys.stdout.flush()
-    sys.stderr.flush()
-
 
 if __name__ == "__main__":
     sys.exit(main(sys.argv))
diff --git a/templates/esp32/test b/templates/esp32/test
index b3f4e81..5935444 100755
--- a/templates/esp32/test
+++ b/templates/esp32/test
@@ -78,7 +78,6 @@ def main(argv):
     build_dir = argv[2]
 
     dut = ESP32(build_dir)
-
     dut.flash()
     dut.prepare()
     sys.stdout.write("Board prepared\n")
@@ -100,9 +99,6 @@ def main(argv):
     finally:
         tool.end_measurement()
 
-    sys.stdout.flush()
-    sys.stderr.flush()
-
 
 if __name__ == "__main__":
     sys.exit(main(sys.argv))
diff --git a/templates/f7/test b/templates/f7/test
index a264297..55968d9 100755
--- a/templates/f7/test
+++ b/templates/f7/test
@@ -10,6 +10,7 @@ from test_common import (
     DeviceUnderTestAeadUARTP,
     compare_dumps,
     eprint,
+    FileMutex,
     run_nist_aead_test_line,
 )
 
@@ -31,12 +32,19 @@ def get_serial():
 class F7(DeviceUnderTestAeadUARTP):
     RAM_SIZE = 0x50000
 
-    def __init__(self, firmware_path, ram_pattern_path):
-        DeviceUnderTestAeadUARTP.__init__(self, get_serial())
+    def __init__(self, build_dir):
+        DeviceUnderTestAeadUARTP.__init__(self)
+
+        self.uart_device = get_serial()
+        devname = os.path.basename(self.uart_device)
+        self.lock = FileMutex('/var/lock/lwc-compare.%s.lock' % devname)
+        self.build_dir = build_dir
+
         self.jlink = pylink.JLink()
         self.jlink.open(779340002)
-        self.firmware_path = firmware_path
-        self.ram_pattern_path = ram_pattern_path
+
+        self.firmware_path = os.path.join(build_dir, 'build', 'f7.bin')
+        self.ram_pattern_path = os.path.join(build_dir, 'ram_pattern.bin')
 
     def flash(self):
         jlink = self.jlink
@@ -61,21 +69,19 @@ def main(argv):
     kat = list(parse_nist_aead_test_vectors(argv[1]))
     build_dir = argv[2]
 
-    dut = F7(
-        os.path.join(build_dir, 'build', 'f7.bin'),
-        os.path.join(build_dir, 'ram_pattern.bin'))
+    dut = F7(build_dir)
+
+    dut.flash()
+    dut.prepare()
+    sys.stdout.write("Board prepared\n")
+    sys.stdout.flush()
+
+    dump_a = dut.dump_ram()
 
     try:
         tool = LogicMultiplexerTimeMeasurements(0x000c)
         tool.begin_measurement()
 
-        dut.flash()
-        dut.prepare()
-        sys.stdout.write("Board prepared\n")
-        sys.stdout.flush()
-
-        dump_a = dut.dump_ram()
-
         for i, m, ad, k, npub, c in kat:
             tool.arm()
             run_nist_aead_test_line(dut, i, m, ad, k, npub, c)
@@ -92,8 +98,6 @@ def main(argv):
 
     finally:
         tool.end_measurement()
-        sys.stdout.flush()
-        sys.stderr.flush()
 
 
 if __name__ == "__main__":
diff --git a/templates/maixduino/test b/templates/maixduino/test
index 4e0dab5..8a2b728 100755
--- a/templates/maixduino/test
+++ b/templates/maixduino/test
@@ -9,6 +9,7 @@ from test_common import (
     LogicMultiplexerTimeMeasurements,
     parse_nist_aead_test_vectors,
     DeviceUnderTestAeadUARTP,
+    FileMutex,
     eprint,
     run_nist_aead_test_line,
 )
@@ -31,19 +32,38 @@ class Maixduino(DeviceUnderTestAeadUARTP):
     def __init__(self, build_dir):
         DeviceUnderTestAeadUARTP.__init__(self)
 
+        self.uart_device = get_serial()
+        devname = os.path.basename(self.uart_device)
+        self.lock = FileMutex('/var/lock/lwc-compare.%s.lock' % devname)
         self.build_dir = build_dir
 
+    def reset(self):
+        self.ser.setRTS(True)
+        time.sleep(0.1)
+        self.ser.setRTS(False)
+        time.sleep(0.1)
+        self.ser.setRTS(True)
+        time.sleep(1)
+
+    def prepare(self):
+        self.ser = serial.Serial(
+            self.uart_device,
+            baudrate=1500000,
+            timeout=5)
+        self.reset()
+        DeviceUnderTestAeadUARTP.prepare(self)
+
     def flash(self):
         pipe = subprocess.PIPE
         previous_dir = os.path.abspath(os.curdir)
         os.chdir(self.build_dir)
         cmd = ['platformio', 'run', '-e', 'sipeed-maixduino']
         cmd.extend(['--target', 'upload'])
-        cmd.extend(['--upload-port', get_serial()])
-        cmd.extend(['--upload-port', get_serial()])
+        cmd.extend(['--upload-port', self.uart_device])
         p = subprocess.Popen(
             cmd, stdout=sys.stderr, stdin=pipe)
         stdout, stderr = p.communicate("")
+        assert p.returncode == 0
         eprint("Firmware flashed.")
         os.chdir(previous_dir)
 
@@ -60,31 +80,15 @@ def main(argv):
     build_dir = argv[2]
 
     dut = Maixduino(build_dir)
+    dut.flash()
+    dut.prepare()
+    sys.stdout.write("Board prepared\n")
+    sys.stdout.flush()
 
     try:
         tool = LogicMultiplexerTimeMeasurements(0x00c0)
         tool.begin_measurement()
 
-        dut.flash()
-
-        ser = serial.Serial(
-            get_serial(),
-            baudrate=1500000,
-            timeout=5)
-
-        ser.setRTS(True)
-        time.sleep(0.1)
-        ser.setRTS(False)
-        time.sleep(0.1)
-        ser.setRTS(True)
-        time.sleep(1)
-
-        dut.ser = ser
-
-        dut.prepare()
-        sys.stdout.write("Board prepared\n")
-        sys.stdout.flush()
-
         for i, m, ad, k, npub, c in kat:
             tool.arm()
             run_nist_aead_test_line(dut, i, m, ad, k, npub, c)
@@ -96,12 +100,6 @@ def main(argv):
 
     finally:
         tool.end_measurement()
-        sys.stdout.flush()
-        sys.stderr.flush()
-
-
-if __name__ == "__main__":
-    sys.exit(main(sys.argv))
 
 
 if __name__ == "__main__":
diff --git a/templates/uno/test b/templates/uno/test
index ec5dfed..cabef18 100755
--- a/templates/uno/test
+++ b/templates/uno/test
@@ -98,9 +98,6 @@ def main(argv):
     finally:
         tool.end_measurement()
 
-    sys.stdout.flush()
-    sys.stderr.flush()
-
 
 if __name__ == "__main__":
     sys.exit(main(sys.argv))