Added address claim code

device.py

@@ -3,6 +3,9 @@ NMEA2000-Gerät
 - auf dem Bus erkannte Geräte
 - für das eigene Gerät steht initUid() zur Verfügung
 
+TODO
+- logging
+
 """
 
 import time
@@ -74,6 +77,62 @@ class Device():
         self.NAME = struct.unpack_from('<Q', data, 0)[0]
         return data
 
+    def send_address_claim(self, bus):
+        data = self.getNAME()
+        print("sending address claim for '{}' with name {} ...".format(self.address, data))
+        priority = 6
+        pgn = 60928
+        msg = can.Message(
+            arbitration_id = (((priority << 18) + pgn) << 8) + self.address,
+            data = data,
+            is_extended_id = True
+        );
+        try:
+            bus.send(msg)
+            print(f"Address claim sent to bus {bus.channel_info}")
+        except can.CanError:
+            print("Address claim NOT sent")
+
+    def claim_address(self, bus):
+        self.send_address_claim(bus)
+        pgn = None
+        claim_ok = False
+        t0 = time.monotonic()
+        while not time.monotonic() - t0 > 0.25:
+            # recv ist blocking. if timeout reached msg should be None
+            msg = bus.recv(0.25)
+            if msg:
+                baseid = (msg.arbitration_id & 0x3ffff00) >> 8
+                pgn = baseid & 0xffff00
+                if not pgn == 60928:
+                    continue
+                dest = baseid & 0x0000ff
+                if dest == 0xff:
+                    print("Claim detected for 0xff (broadcast)")
+                    if self.NAME > struct.unpack_from('<Q', msg.data, 0)[0]:
+                        # collision we have a lower priority:
+                        # start over with new address
+                        print("Address is in use, trying next one")
+                        t0 = time.monotonic()
+                        owndevice.address += 1
+                        send_address_claim(bus)
+                    else:
+                        print("Ignore collision because of our lower NAME")
+                else:
+                    print(f"Answer: DEST={dest}")
+                    print(msg.data)
+                    if dest == self.address:
+                        print("We are addressed: WIP!")
+                    else:
+                        print("Frame ist not for us.")
+            else:
+                # timeout without answer
+                print("Timeout after claim. Keep selected address")
+                claim_ok = True
+        if not claim_ok and (time.monotonic() - t0 > 0.25):
+            print("claim seems ok after 250ms")
+        return claim_ok
+
     def __str__(self):
         out =  f"Device: {self.address} : '{self.product}'\n"
         out +=  "  NAME: {} ({})\n".format(self.getNAME(), self.NAME)