K line fix (#559)

* enable UART RX interrupts

* update debug prints for python3

* improve kline functions and fix checksum

* k-line wake-up conforming to KWP2000 fast init

* fix timing

* toggle k and l line together by default

* k-line wakeup using timer

* k and l were flipped

* fix misra compliance

python/__init__.py

@@ -1,6 +1,5 @@
 # python library to interface with panda
 import datetime
-import binascii
 import struct
 import hashlib
 import socket
@@ -44,7 +43,7 @@ def parse_can_buffer(dat):
       address = f1 >> 21
     dddat = ddat[8:8 + (f2 & 0xF)]
     if DEBUG:
-      print("  R %x: %s" % (address, binascii.hexlify(dddat)))
+      print(f"  R 0x{address:x}: 0x{dddat.hex()}")
     ret.append((address, f2 >> 16, dddat, (f2 >> 4) & 0xFF))
   return ret
 
@@ -489,7 +488,7 @@ class Panda(object):
     for addr, _, dat, bus in arr:
       assert len(dat) <= 8
       if DEBUG:
-        print("  W %x: %s" % (addr, binascii.hexlify(dat)))
+        print(f"  W 0x{addr:x}: 0x{dat.hex()}")
       if addr >= 0x800:
         rir = (addr << 3) | transmit | extended
       else:
@@ -572,10 +571,11 @@ class Panda(object):
   # ******************* kline *******************
 
   # pulse low for wakeup
-  def kline_wakeup(self):
+  def kline_wakeup(self, k=True, l=True):
+    assert k or l, "must specify k-line, l-line, or both"
     if DEBUG:
       print("kline wakeup...")
-    self._handle.controlWrite(Panda.REQUEST_OUT, 0xf0, 0, 0, b'')
+    self._handle.controlWrite(Panda.REQUEST_OUT, 0xf0, 2 if k and l else int(l), 0, b'')
     if DEBUG:
       print("kline wakeup done")
 
@@ -587,7 +587,7 @@ class Panda(object):
       if len(ret) == 0:
         break
       elif DEBUG:
-        print("kline drain: " + binascii.hexlify(ret))
+        print(f"kline drain: 0x{ret.hex()}")
       bret += ret
     return bytes(bret)
 
@@ -596,35 +596,31 @@ class Panda(object):
     while len(echo) != cnt:
       ret = self._handle.controlRead(Panda.REQUEST_OUT, 0xe0, bus, 0, cnt - len(echo))
       if DEBUG and len(ret) > 0:
-        print("kline recv: " + binascii.hexlify(ret))
+        print(f"kline recv: 0x{ret.hex()}")
       echo += ret
     return bytes(echo)
 
   def kline_send(self, x, bus=2, checksum=True):
-    def get_checksum(dat):
-      result = 0
-      result += sum(map(ord, dat)) if isinstance(b'dat', str) else sum(dat)
-      result = -result
-      return struct.pack("B", result % 0x100)
-
     self.kline_drain(bus=bus)
     if checksum:
-      x += get_checksum(x)
+      x += bytes([sum(x) % 0x100])
     for i in range(0, len(x), 0xf):
       ts = x[i:i + 0xf]
       if DEBUG:
-        print("kline send: " + binascii.hexlify(ts))
+        print(f"kline send: 0x{ts.hex()}")
       self._handle.bulkWrite(2, bytes([bus]) + ts)
       echo = self.kline_ll_recv(len(ts), bus=bus)
       if echo != ts:
-        print("**** ECHO ERROR %d ****" % i)
-        print(binascii.hexlify(echo))
-        print(binascii.hexlify(ts))
+        print(f"**** ECHO ERROR {i} ****")
+        print(f"0x{echo.hex()}")
+        print(f"0x{ts.hex()}")
     assert echo == ts
 
-  def kline_recv(self, bus=2):
-    msg = self.kline_ll_recv(2, bus=bus)
-    msg += self.kline_ll_recv(ord(msg[1]) - 2, bus=bus)
+  def kline_recv(self, bus=2, header_len=4):
+    # read header (last byte is length)
+    msg = self.kline_ll_recv(header_len, bus=bus)
+    # read data (add one byte to length for checksum)
+    msg += self.kline_ll_recv(msg[-1]+1, bus=bus)
     return msg
 
   def send_heartbeat(self):