mnl100: control attenuator

mnl100.py

@@ -1,5 +1,28 @@
 import time
 import serial
+import sys
+import termios
+import select
+
+
+class GetKey:
+    def __enter__(self):
+        self.fd = sys.stdin.fileno()
+        self.old = termios.tcgetattr(self.fd)
+        new = termios.tcgetattr(self.fd)
+        new[3] = new[3] & ~termios.ECHO & ~termios.ICANON
+        termios.tcsetattr(self.fd, termios.TCSAFLUSH, new)
+        return self
+
+    def  __exit__(self, ty, value, tb):
+        termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.old)
+
+    def get(self, timeout):
+        r, w, e = select.select([sys.stdin], [], [], timeout)
+        if r:
+            return sys.stdin.read(1)
+        else:
+            return None
 
 
 def main():
@@ -34,10 +57,28 @@ def main():
             print("laser is on")
             transact(b"u")   # ExtTrigmode
             print("laser is ready")
-            # keep the laser on (auto-shutdown if no comms for 30s)
+
+            transmission = 200
             while True:
-                transact(b"W")  # GetShortStatus
-                time.sleep(5.0)
+                with GetKey() as gc:
+                    match gc.get(5):
+                        case "q":
+                            return
+                        case "+":
+                            transmission += 1
+                            if transmission > 200:
+                                transmission = 200
+                            transact(bytes("O4{:02X}".format(transmission), "ascii"))
+                            print("transmission:", transmission)
+                        case "-":
+                            transmission -= 1
+                            if transmission < 0:
+                                transmission = 0
+                            transact(bytes("O4{:02X}".format(transmission), "ascii"))
+                            print("transmission:", transmission)
+                        case None:
+                            # keep the laser on (auto-shutdown if no comms for 30s)
+                            transact(b"W")  # GetShortStatus
         finally:
             transact(b"X")  # laser off
             print("laser is off")