Output syslink packets on pi

salt/drone/scripts/uart_test.py

 #!/usr/bin/python
 
 import serial
-from time import sleep
 
-ser = serial.Serial("/dev/ttyS0", 115200)     # Open port with baud rate
+MTU = 32
+START_BYTE1 = 0xbc
+START_BYTE2 = 0xcf
+START = [START_BYTE1, START_BYTE2]
+
+received_data = []
+
+ser = serial.Serial("/dev/ttyS0", 115200)
+
 while True:
-#    received_data = ser.read()              # read serial port
-#    sleep(0.03)
-#    data_left = ser.inWaiting()             # check for remaining byte
-#    received_data += ser.read(data_left)
-#    print(list(received_data))              # print received data
-#    ser.write(received_data)                # transmit data serially
-
-    data_left = 1
-    received_data = ""
-    while data_left:
-        received_data += ser.read()
-        sleep(0.003)
-        data_left = ser.inWaiting()
-    print(list(received_data))
+
+    received_data = map(ord, list(ser.read_until(chr(START_BYTE1))))
+    received_data += map(ord, list(ser.read(1)))
+    if received_data[1] != START_BYTE2:
+        print("ERROR START")
+        continue
+
+    received_data += map(ord, list(ser.read(2)))
+    if received_data[3] > MTU:
+        print("ERROR LENGTH")
+        continue
+
+    received_data += map(ord, list(ser.read(received_data[3]+2)))
+    cksum0 = 0
+    cksum1 = 0
+    for c in received_data[2:-2]:
+        cksum0 = (cksum0 + c) & 0xff
+        cksum1 = (cksum1 + cksum0) & 0xff
+    if cksum0 != received_data[-2] or cksum1 != received_data[-1]:
+        print("ERROR CKSUM")
+
+    print(" ".join("{:#04x}".format(n) for n in received_data))