fix: ground-truth CI-V offset/tone on live ID-5100

- offset amount (0x0D) is REJECTED (NG) by the radio -> removed the offset
  codec + set_offset/get_offset; tune_repeater now sets only duplex direction
  (radio applies its configured auto-offset)
- repeater tone (0x1B/00) uses a 3-byte field (00 + 2-byte BCD); set_tone
  prepends the pad, get_tone strips it
- duplex (0x0F) and tone-switch (0x16/42) verified working
- added get_duplex; verified full tune_repeater on a live repeater (all steps OK)

civ.py

@@ -24,15 +24,17 @@ SUB_SQL_LEVEL = 0x03
 SUB_SQL_STATUS = 0x01
 SUB_SMETER = 0x02
 
-# --- repeater config (candidate commands; verify on live radio) ---
+# --- repeater config (verified on live ID-5100 2026-06-14) ---
-CMD_OFFSET = 0x0D       # set duplex offset frequency
+# NOTE: offset-amount cmd 0x0D is REJECTED (NG) by the ID-5100 — the offset
-CMD_DUPLEX = 0x0F       # set duplex direction
+# amount is not CI-V-settable; the radio applies its configured auto-offset
+# (default 0.6 MHz / 5 MHz) when a duplex direction is selected via 0x0F.
+CMD_DUPLEX = 0x0F       # set/read duplex direction (verified: read -> 0x10 simplex)
 DUP_SIMPLEX = 0x10
 DUP_MINUS = 0x11
 DUP_PLUS = 0x12
-CMD_TONE_PARAM = 0x1B   # sub 0x00 = repeater (TX) tone frequency
+CMD_TONE_PARAM = 0x1B   # sub 0x00 = repeater (TX) tone freq (verified)
 SUB_RPT_TONE = 0x00
-CMD_TONE_SWITCH = 0x16  # sub 0x42 = tone encode on/off
+CMD_TONE_SWITCH = 0x16  # sub 0x42 = tone encode on/off (verified)
 SUB_TONE_ENC = 0x42
 
 Frame = namedtuple("Frame", "to frm cn data")
@@ -77,28 +79,12 @@ def bcd_to_level(data):
     return value
 
 
-def offset_to_bcd(hz):
-    """Duplex offset Hz -> 3-byte little-endian BCD in 100 Hz units (PROVISIONAL)."""
-    if hz < 0:
-        raise ValueError(f"offset {hz} must be >= 0")
-    units = round(hz / 100)
-    digits = f"{units:06d}"
-    out = bytearray()
-    for i in range(0, 6, 2):
-        out.append((int(digits[4 - i]) << 4) | int(digits[5 - i]))
-    return bytes(out)
-
-
-def bcd_to_offset(data):
-    """3-byte little-endian BCD (100 Hz units) -> Hz (PROVISIONAL)."""
-    units = 0
-    for i, byte in enumerate(data[:3]):
-        units += (byte & 0x0F) * (10 ** (2 * i)) + (byte >> 4) * (10 ** (2 * i + 1))
-    return units * 100
-
-
 def tone_to_bcd(hz):
-    """CTCSS tone Hz -> 2-byte BCD of tone*10 (88.5 -> 08 85)."""
+    """CTCSS tone Hz -> 2-byte BCD of tone*10 (88.5 -> 08 85).
+
+    The ID-5100 wire format for cmd 0x1B/0x00 prepends a 0x00 pad byte before
+    these two (so 88.5 Hz reads/writes as `00 08 85`); radio.py adds/strips it.
+    """
     digits = f"{round(hz * 10):04d}"
     return bytes([(int(digits[0]) << 4) | int(digits[1]),
                   (int(digits[2]) << 4) | int(digits[3])])

radio.py

@@ -157,35 +157,39 @@ class Radio:
         data = self.transact(civ.CMD_METER, bytes([civ.SUB_SQL_STATUS])).data
         return bool(data[1]) if len(data) > 1 else False
 
-    # ---- repeater config (candidate commands; verify live) ----------------
+    # ---- repeater config (verified on live ID-5100 2026-06-14) ------------
+    # Offset *amount* is not CI-V-settable on this radio (cmd 0x0D -> NG); the
+    # radio applies its configured auto-offset when a duplex direction is set.
     def set_duplex(self, direction):
-        """direction: '+', '-', or 'simplex'."""
+        """direction: '+', '-', or 'simplex'. Radio uses its configured offset."""
         code = {"+": civ.DUP_PLUS, "-": civ.DUP_MINUS,
                 "simplex": civ.DUP_SIMPLEX}.get(direction)
         if code is None:
             raise ValueError(f"bad duplex {direction!r}")
         return self._command(civ.CMD_DUPLEX, bytes([code]))
 
-    def set_offset(self, hz):
+    def get_duplex(self):
-        return self._command(civ.CMD_OFFSET, civ.offset_to_bcd(hz))
+        code = self.transact(civ.CMD_DUPLEX).data[0]
-
+        return {civ.DUP_PLUS: "+", civ.DUP_MINUS: "-",
-    def get_offset(self):
+                civ.DUP_SIMPLEX: "simplex"}.get(code, f"0x{code:02X}")
-        return civ.bcd_to_offset(self.transact(civ.CMD_OFFSET).data)
 
     def set_tone(self, hz):
+        # wire format: sub(0x00) + 0x00 pad + 2-byte BCD (00 00 08 85 = 88.5 Hz)
         return self._command(civ.CMD_TONE_PARAM,
-                             bytes([civ.SUB_RPT_TONE]) + civ.tone_to_bcd(hz))
+                             bytes([civ.SUB_RPT_TONE, 0x00]) + civ.tone_to_bcd(hz))
 
     def get_tone(self):
+        # reply data = sub + pad + 2-byte BCD; take the last two bytes
         return civ.bcd_to_tone(self.transact(civ.CMD_TONE_PARAM,
-                                             bytes([civ.SUB_RPT_TONE])).data[1:])
+                                             bytes([civ.SUB_RPT_TONE])).data[2:])
 
     def set_tone_on(self, on):
         return self._command(civ.CMD_TONE_SWITCH,
                              bytes([civ.SUB_TONE_ENC, 0x01 if on else 0x00]))
 
     def tune_repeater(self, rec):
-        """Apply a normalized record: freq -> duplex/offset -> tone.
+        """Apply a normalized record: freq -> duplex direction -> tone.
+        Offset amount comes from the radio's own config (not CI-V-settable).
         Returns (steps, errors): each step True/False; errors keyed by step."""
         steps, errors = {}, {}
 
@@ -196,10 +200,7 @@ class Radio:
                 steps[name] = False; errors[name] = str(e)
 
         attempt("freq", lambda: self.set_frequency(int(round(rec["output_mhz"] * 1e6))))
-        duplex = rec.get("duplex", "simplex")
+        attempt("duplex", lambda: self.set_duplex(rec.get("duplex", "simplex")))
-        attempt("duplex", lambda: self.set_duplex(duplex))
-        if duplex != "simplex":
-            attempt("offset", lambda: self.set_offset(int(round(rec.get("offset_mhz", 0) * 1e6))))
         if rec.get("tone_mode") == "ctcss" and rec.get("tone_hz"):
             attempt("tone_freq", lambda: self.set_tone(rec["tone_hz"]))
             attempt("tone_on", lambda: self.set_tone_on(True))

test_civ.py

@@ -73,23 +73,10 @@ class TestParseFrames(unittest.TestCase):
         self.assertEqual(civ.parse_frames(b""), [])
 
 
-class TestOffsetCodec(unittest.TestCase):
-    # PROVISIONAL: 3-byte little-endian BCD in units of 100 Hz.
-    # Round-trip validated until pinned to a real capture (plan Task 6).
-    def test_offset_roundtrip(self):
-        for hz in (600_000, 5_000_000, 1_600_000, 0):
-            self.assertEqual(civ.bcd_to_offset(civ.offset_to_bcd(hz)), hz)
-
-    def test_offset_is_three_bytes(self):
-        self.assertEqual(len(civ.offset_to_bcd(600_000)), 3)
-
-    def test_offset_rejects_negative(self):
-        with self.assertRaises(ValueError):
-            civ.offset_to_bcd(-1)
-
-
 class TestToneCodec(unittest.TestCase):
     # ICOM convention: CTCSS tone as 2-byte BCD of tone*10. 131.8 -> "13 18".
+    # Verified on the live ID-5100: cmd 0x1B/0x00 returned `00 08 85` for 88.5 Hz
+    # (a 0x00 pad byte precedes these two; radio.py handles the pad).
     def test_tone_to_bcd_known(self):
         self.assertEqual(civ.tone_to_bcd(88.5), b"\x08\x85")
         self.assertEqual(civ.tone_to_bcd(131.8), b"\x13\x18")