Upload openbci_impedance.py

openbci_impedance.py

@@ -51,7 +51,7 @@ SCALE_UV     = (ADS1299_VREF / ADS1299_GAIN) / (2**23 - 1) * 1_000_000
 # Pleine echelle ADS1299 en µV (seuil railing)
 ADC_MAX_UV   = (2**23 - 1) * SCALE_UV   # ≈ 187 500 µV
 
-LEAD_OFF_FREQ    = 31.25     # Hz — fréquence exacte ADS1299 (31.25 Hz, pas 31.5)
+LEAD_OFF_FREQ    = 31.25     # Hz — fréquence exacte ADS1299
 LEAD_OFF_AMPS    = 6e-9      # A
 SERIES_RESISTOR  = 2200      # Ω
 
@@ -142,19 +142,15 @@ def parse_packet(data: bytes):
         return None
     if data[0] != START_BYTE:
         return None
-    stop_byte = data[32]
-    if (stop_byte & 0xF0) != 0xC0:
+    if (data[32] & 0xF0) != 0xC0:
         return None
     sample_num = data[1]
-    # FIX : stop byte 0xC0 = Cyton packet, 0xC1 = Daisy packet
-    # C'est le nibble bas qui indique la source, PAS la parité du sample_num
-    is_daisy = (stop_byte & 0x0F) == 0x01
     channels_uv = []
     for ch in range(8):
         offset = 2 + ch * 3
         raw = parse_24bit_signed(data[offset], data[offset+1], data[offset+2])
         channels_uv.append(raw * SCALE_UV)
-    return sample_num, channels_uv, is_daisy
+    return sample_num, channels_uv
 
 
 # ╔══════════════════════════════════════════════════╗
@@ -186,7 +182,7 @@ def _make_bandpass_sos(low_hz: float, high_hz: float, order: int = 4,
 # Pre-calculer les filtres une seule fois
 # Californie = reseau 60 Hz uniquement (pas de 50 Hz)
 _NOTCH_60_SOS  = _make_notch_sos(60.0)
-_BANDPASS_SOS  = _make_bandpass_sos(30.5, 32.0)   # FIX : bande étroite ±0.75 Hz autour de 31.25 Hz
+_BANDPASS_SOS  = _make_bandpass_sos(30.5, 32.0)   # bande étroite ±0.75 Hz autour de 31.25 Hz
 
 
 # ╔══════════════════════════════════════════════════╗
@@ -257,6 +253,8 @@ class CytonDaisyBoard:
 
         self._buf_size = SAMPLE_RATE * 4
         self._buffers  = [deque(maxlen=self._buf_size) for _ in range(N_CHANNELS)]
+        self._last_cyton_data = None
+        self._last_cyton_snum = None
         self._rx_thread = None
 
     def connect(self):
@@ -421,17 +419,28 @@ class CytonDaisyBoard:
                 print(f"[Board] Erreur lecture : {e}")
                 time.sleep(0.005)
 
-    def _handle_sample(self, sample_num: int, ch_data_uv: list, is_daisy: bool):
-        # FIX : on utilise le flag is_daisy du stop byte, pas la parité du sample_num
+    def _handle_sample(self, sample_num: int, ch_data_uv: list):
+        # Protocole OpenBCI Cyton+Daisy : odd sample_num = Cyton, even = Daisy
+        # Ref: https://docs.openbci.com/Cyton/CytonDataFormat/
+        is_cyton = (sample_num % 2) == 1
         with self._lock:
-            if not is_daisy:
-                # Packet Cyton → canaux 0-7, on stocke directement
-                for i in range(8):
-                    self._buffers[i].append(ch_data_uv[i])
+            if is_cyton:
+                self._last_cyton_data  = ch_data_uv[:]
+                self._last_cyton_snum  = sample_num
             else:
-                # Packet Daisy → canaux 8-15
-                for i in range(8):
-                    self._buffers[8 + i].append(ch_data_uv[i])
+                # Vérification de cohérence : le sample Daisy doit suivre
+                # immédiatement le sample Cyton (sample_num = last_cyton + 1)
+                if self._last_cyton_data is not None:
+                    expected = (self._last_cyton_snum + 1) % 256
+                    if sample_num != expected:
+                        # Désynchronisation — on jette ce couple et on repart
+                        self._last_cyton_data = None
+                        return
+                    for i in range(8):
+                        self._buffers[i].append(self._last_cyton_data[i])
+                    for i in range(8):
+                        self._buffers[8 + i].append(ch_data_uv[i])
+                    self._last_cyton_data = None
 
     def get_impedances(self) -> list:
         with self._lock: