Chrsyler: calculate checksum in CAN packer (#1438)

opendbc

@@ -1 +1 @@
-Subproject commit 0c0215516f6a0be50fcbe7fc1e8e2fe0f47f9d86
+Subproject commit 7456061a7150911a8c186231453a337e6c73c743

selfdrive/car/chrysler/carcontroller.py

@@ -50,7 +50,7 @@ class CarController():
 
     if pcm_cancel_cmd:
       # TODO: would be better to start from frame_2b3
-      new_msg = create_wheel_buttons(self.ccframe)
+      new_msg = create_wheel_buttons(self.packer, self.ccframe, cancel=True)
       can_sends.append(new_msg)
 
     # LKAS_HEARTBIT is forwarded by Panda so no need to send it here.

selfdrive/car/chrysler/chryslercan.py

@@ -5,34 +5,6 @@ from selfdrive.car import make_can_msg
 GearShifter = car.CarState.GearShifter
 VisualAlert = car.CarControl.HUDControl.VisualAlert
 
-def calc_checksum(data):
-  """This function does not want the checksum byte in the input data.
-
-  jeep chrysler canbus checksum from http://illmatics.com/Remote%20Car%20Hacking.pdf
-  """
-  checksum = 0xFF
-  for curr in data[:-1]:
-    shift = 0x80
-    for _ in range(0, 8):
-      bit_sum = curr & shift
-      temp_chk = checksum & 0x80
-      if (bit_sum != 0):
-        bit_sum = 0x1C
-        if (temp_chk != 0):
-          bit_sum = 1
-        checksum = checksum << 1
-        temp_chk = checksum | 1
-        bit_sum ^= temp_chk
-      else:
-        if (temp_chk != 0):
-          bit_sum = 0x1D
-        checksum = checksum << 1
-        bit_sum ^= checksum
-      checksum = bit_sum
-      shift = shift >> 1
-  return ~checksum & 0xFF
-
-
 def create_lkas_hud(packer, gear, lkas_active, hud_alert, hud_count, lkas_car_model):
   # LKAS_HUD 0x2a6 (678) Controls what lane-keeping icon is displayed.
 
@@ -73,18 +45,13 @@ def create_lkas_command(packer, apply_steer, moving_fast, frame):
     "LKAS_HIGH_TORQUE": int(moving_fast),
     "COUNTER": frame % 0x10,
   }
-
-  dat = packer.make_can_msg("LKAS_COMMAND", 0, values)[2]
-  checksum = calc_checksum(dat)
-
-  values["CHECKSUM"] = checksum
   return packer.make_can_msg("LKAS_COMMAND", 0, values)
 
 
-def create_wheel_buttons(frame):
+def create_wheel_buttons(packer, frame, cancel=False):
   # WHEEL_BUTTONS (571) Message sent to cancel ACC.
-  start = b"\x01"  # acc cancel set
-  counter = (frame % 10) << 4
-  dat = start + counter.to_bytes(1, 'little') + b"\x00"
-  dat = dat[:-1] + calc_checksum(dat).to_bytes(1, 'little')
-  return make_can_msg(0x23b, dat, 0)
+  values = {
+    "ACC_CANCEL": cancel,
+    "COUNTER": frame % 10
+  }
+  return packer.make_can_msg("WHEEL_BUTTONS", 0, values)

selfdrive/car/chrysler/test_chryslercan.py

@@ -11,10 +11,6 @@ GearShifter = car.CarState.GearShifter
 
 class TestChryslerCan(unittest.TestCase):
 
-  def test_checksum(self):
-    self.assertEqual(0x75, chryslercan.calc_checksum(b"\x01\x20\x00"))
-    self.assertEqual(0xcc, chryslercan.calc_checksum(b"\x14\x00\x00\x00\x20\x00"))
-
   def test_hud(self):
     packer = CANPacker('chrysler_pacifica_2017_hybrid')
     self.assertEqual(