Adding serial loader script

Author: AGlass0fMilk

serial_loader.py

@@ -0,0 +1,89 @@
+from cobs import cobsr
+import serial
+import argparse
+import struct
+from crc16 import crc16xmodem as crc16
+
+CHUNK_SIZE = 128
+
+
+# Header format:
+# Little Endian
+# CRC16 (2-bytes)
+# Sequence Number (2-bytes)
+# Payload Size (2-bytes)
+HEADER_FORMAT = "<HH".format(CHUNK_SIZE)
+
+
+def read_in_chunks(file_object, chunk_size=256):
+    while True:
+        data = file_object.read(chunk_size)
+        if not data:
+            break
+        yield data
+
+def main():
+
+    parser = argparse.ArgumentParser(description='Upload an update over SerialOTA')
+    parser.add_argument('binary', help='path to binary to upload over SerialOTA')
+    parser.add_argument('port', help='Serial port to use for SerialOTA')
+
+    args = parser.parse_args()
+
+    # Create the OTA serial
+    ser = serial.Serial(args.port, 115200, timeout=0.1)
+
+    # Open the binary
+    with open(args.binary, 'rb') as f:
+
+        # Start by sending 0 bytes until we get a response
+        while True:
+            ser.write(bytes([0]))
+            rx = ser.read()
+            print("received: {}".format(rx))
+            if rx == bytes([1]):
+                print("Received bootloader ACK -- waiting for ready")
+                break
+
+        while True:
+            # Wait until the bootloader sends another response
+            rx = ser.read()
+            print("received: {}".format(rx))
+            if rx == bytes([2]):
+                print("Bootloader ready -- begin upload")
+                break
+
+        ser.flushInput()
+
+        sequence_num = 0
+        for chunk in read_in_chunks(f, CHUNK_SIZE):
+
+            if len(chunk) != CHUNK_SIZE:
+                sequence_num = 0xFFFF
+
+            # Pack the header
+            tx_buf = struct.pack(HEADER_FORMAT, sequence_num, len(chunk)) + chunk
+
+            # Calculate the CRC16 of the chunk and the header info
+            crc = crc16(bytes(tx_buf))
+            print("Sending chunk: crc({}), seq num({}), size({})".format(crc, sequence_num, len(chunk)))
+
+            tx_buf = struct.pack("<H", crc) + tx_buf
+
+            # Encode with COBS
+            tx_cobs = cobsr.encode(tx_buf) + bytes([0])
+            print(type(tx_cobs))
+            ser.write(tx_cobs)
+            print(tx_cobs.hex())
+
+            while(True):
+                # Wait until the bootloader is ready
+                c = ser.read()
+                print("rx:{}".format(c))
+                if c == bytes([0]):
+                    break
+
+            sequence_num = sequence_num + 1
+
+if __name__ == '__main__':
+    main()