Add ability to RF scan a specific frequency (#613)

* Add ability to RF scan a specific frequency

This adds an optional parameter to find_rf_packet(), along with a
corresponding --rflearn parameter (defaulting to 433.92) to
broadlink_cli that specifies the frequency to tune to, rather than
requiring the frequency be found via sweeping. This is almost mandatory
for certain types of remotes that do not repeat their signals while the
button is held, and saves significant time when the frequency is known
in advance or when many buttons are to be captured in a row.

Additionally:

- A get_frequency() API is added to return the current frequency the
  device is tuned to.

- A check_frequency_ex() API is added to perform functions of both
  check_frequency() and get_frequency() in a single call.

- broadlink_cli --rfscanlearn will now report the current frequency at 1
  second intervals during sweeping, and will report the frequency it
  finally locks on to.

* Clean up remote.py

* Clean up broadlink_cli

* Update conditional

* Fix message

---------

Co-authored-by: Felipe Martins Diel <41558831+felipediel@users.noreply.github.com>

broadlink/remote.py

@@ -1,5 +1,6 @@
 """Support for universal remotes."""
 import struct
+import typing as t
 
 from . import exceptions as e
 from .device import Device
@@ -46,14 +47,19 @@ def sweep_frequency(self) -> None:
         """Sweep frequency."""
         self._send(0x19)
 
-    def check_frequency(self) -> bool:
+    def check_frequency(self) -> t.Tuple[bool, float]:
         """Return True if the frequency was identified successfully."""
         resp = self._send(0x1A)
-        return resp[0] == 1
+        is_found = bool(resp[0])
+        frequency = struct.unpack("<I", resp[1:5])[0] / 1000.0
+        return is_found, frequency
 
-    def find_rf_packet(self) -> None:
+    def find_rf_packet(self, frequency: float = None) -> None:
         """Enter radiofrequency learning mode."""
-        self._send(0x1B)
+        payload = bytearray()
+        if frequency:
+            payload += struct.pack("<I", int(frequency * 1000))
+        self._send(0x1B, payload)
 
     def cancel_sweep_frequency(self) -> None:
         """Cancel sweep frequency."""

cli/broadlink_cli

@@ -83,7 +83,8 @@ parser.add_argument("--switch", action="store_true", help="switch state from on
 parser.add_argument("--send", action="store_true", help="send command")
 parser.add_argument("--sensors", action="store_true", help="check all sensors")
 parser.add_argument("--learn", action="store_true", help="learn command")
-parser.add_argument("--rfscanlearn", action="store_true", help="rf scan learning")
+parser.add_argument("--rflearn", action="store_true", help="rf scan learning")
+parser.add_argument("--frequency", type=float, help="specify radiofrequency for learning")
 parser.add_argument("--learnfile", help="save learned command to a specified file")
 parser.add_argument("--durations", action="store_true",
                     help="use durations in micro seconds instead of the Broadlink format")
@@ -127,7 +128,7 @@ if args.send:
     data = durations_to_broadlink(parse_durations(' '.join(args.data))) \
         if args.durations else bytearray.fromhex(''.join(args.data))
     dev.send_data(data)
-if args.learn or (args.learnfile and not args.rfscanlearn):
+if args.learn or (args.learnfile and not args.rflearn):
     dev.enter_learning()
     print("Learning...")
     start = time.time()
@@ -195,28 +196,33 @@ if args.switch:
     else:
         dev.set_power(True)
         print('* Switch to ON *')
-if args.rfscanlearn:
-    dev.sweep_frequency()
-    print("Learning RF Frequency, press and hold the button to learn...")
-
-    start = time.time()
-    while time.time() - start < TIMEOUT:
-        time.sleep(1)
-        if dev.check_frequency():
-            break
+if args.rflearn:
+    if args.frequency:
+        frequency = args.frequency
+        print("Press the button you want to learn, a short press...")
     else:
-        print("RF Frequency not found")
-        dev.cancel_sweep_frequency()
-        exit(1)
+        dev.sweep_frequency()
+        print("Detecting radiofrequency, press and hold the button to learn...")
+
+        start = time.time()
+        while time.time() - start < TIMEOUT:
+            time.sleep(1)
+            locked, frequency = dev.check_frequency()
+            if locked:
+                break
+        else:
+            print("Radiofrequency not found")
+            dev.cancel_sweep_frequency()
+            exit(1)
 
-    print("Found RF Frequency - 1 of 2!")
-    print("You can now let go of the button")
+        print("Radiofrequency detected: {}MHz".format(frequency))
+        print("You can now let go of the button")
 
-    input("Press enter to continue...")
+        input("Press enter to continue...")
 
-    print("To complete learning, single press the button you want to learn")
+        print("Press the button again, now a short press.")
 
-    dev.find_rf_packet()
+    dev.find_rf_packet(frequency)
 
     start = time.time()
     while time.time() - start < TIMEOUT:
@@ -231,7 +237,7 @@ if args.rfscanlearn:
         print("No data received...")
         exit(1)
 
-    print("Found RF Frequency - 2 of 2!")
+    print("Packet found!")
     learned = format_durations(to_microseconds(bytearray(data))) \
         if args.durations \
         else ''.join(format(x, '02x') for x in bytearray(data))