diff --git a/nac3embedded/demo.py b/nac3embedded/demo.py
index a5581783..4d784f1f 100644
--- a/nac3embedded/demo.py
+++ b/nac3embedded/demo.py
@@ -54,15 +54,50 @@ class Core:
         if now_mu() < min_now:
             at_mu(min_now)
 
+@kernel
+class TTLOut:
+    channel: int32
+    target_o: int32
+
+    @kernel
+    def __init__(self, channel: int32):
+        self.channel = channel
+        self.target_o = channel << 8
+
+    @kernel
+    def output(self):
+        pass
+
+    @kernel
+    def set_o(self, o: bool):
+        rtio_output(self.target_o, 1 if o else 0)
+
+    @kernel
+    def on(self):
+        self.set_o(True)
+
+    @kernel
+    def off(self):
+        self.set_o(False)
+
+    @kernel
+    def pulse_mu(self, duration: int64):
+        self.on()
+        delay_mu(duration)
+        self.off()
+
 
 @kernel
 class Demo:
     @kernel
     def run(self):
         core = Core()
+        led = TTLOut(0)
 
         core.reset()
-        rtio_init()
+        while True:
+            led.pulse_mu(int64(100000000))
+            delay_mu(int64(100000000))
 
 
 if __name__ == "__main__":