Examples for Python client library

python/README.md

@@ -16,8 +16,36 @@ pip install libsbp
 ```python
 ```
 
+## Examples
+
+### Simple example
+
+Receives SBP messages over a serial port, decodes `MSG_BASELINE` messages and
+prints them out.
+
+See the [`source code`](sbp/client/examples/simple.py).
+
+Run this example with:
+
+```shell
+$ python -m sbp.client.examples.simple -p /path/to/serial/port
+```
+
+### Sending SBP messages over UDP
+
+Receives SBP messages over a serial port and sends all incoming messages to a
+UDP socket.
+
+See the [`source code`](sbp/client/examples/udp.py).
+
+Run this example with:
+
+```shell
+$ python -m sbp.client.examples.udp -s /path/to/serial/port
+```
+
 ## LICENSE
 
 Copyright © 2015 Swift Navigation
 
-Distributed under LGPLv3.0.
+Distributed under LGPLv3.0.

python/sbp/client/examples/simple.py

@@ -0,0 +1,64 @@
+# Copyright (C) 2015 Swift Navigation Inc.
+# Contact: Fergus Noble <fergus@swiftnav.com>
+#
+# This source is subject to the license found in the file 'LICENSE' which must
+# be be distributed together with this source. All other rights reserved.
+#
+# THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+# EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
+
+"""
+the :mod:`sbp.client.examples.simple` module contains a basic example of
+reading SBP messages from a serial port, decoding BASELINE_NED messages and
+printing them out.
+"""
+
+from sbp.client.drivers.pyserial_driver import PySerialDriver
+from sbp.client.handler import Handler
+from sbp.navigation import SBP_MSG_BASELINE_NED, MsgBaselineNED
+
+import time
+
+def baseline_callback(msg):
+  # This function is called every time we receive a BASELINE_NED message
+
+  # First decode the SBP message in "msg" into a python object, the sbp library
+  # has functions that do this for all the message types defined in the
+  # specification.
+  b = MsgBaselineNED(msg)
+
+  # b now contains the decoded baseline information and
+  # has fields with the same names as in the SBP docs
+
+  # Print out the N, E, D coordinates of the baseline
+  print "%.4f,%.4f,%.4f" % \
+    (b.n * 1e-3, b.e * 1e-3, b.d * 1e-3)
+
+def main():
+
+  import argparse
+  parser = argparse.ArgumentParser(description="Swift Navigation SBP Example.")
+  parser.add_argument("-p", "--port",
+                      default=['/dev/ttyUSB0'], nargs=1,
+                      help="specify the serial port to use.")
+  args = parser.parse_args()
+
+  # Open a connection to Piksi using the default baud rate (1Mbaud)
+  with PySerialDriver(args.port[0], baud=1000000) as driver:
+    # Create a handler to connect our Piksi driver to our callbacks
+    with Handler(driver.read, driver.write, verbose=True) as handler:
+      # Add a callback for BASELINE_NED messages
+      handler.add_callback(baseline_callback, msg_type=SBP_MSG_BASELINE_NED)
+      handler.start()
+
+      # Sleep until the user presses Ctrl-C
+      try:
+        while True:
+          time.sleep(0.1)
+      except KeyboardInterrupt:
+        pass
+
+if __name__ == "__main__":
+  main()
+

python/sbp/client/examples/udp.py

@@ -0,0 +1,79 @@
+# Copyright (C) 2015 Swift Navigation Inc.
+# Contact: Fergus Noble <fergus@swiftnav.com>
+#
+# This source is subject to the license found in the file 'LICENSE' which must
+# be be distributed together with this source. All other rights reserved.
+#
+# THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+# EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
+
+"""
+the :mod:`sbp.client.examples.udp` module contains an example of reading SBP
+messages from a serial port and sending them to a UDP socket.
+"""
+
+from sbp.client.drivers.pyserial_driver import PySerialDriver
+from sbp.client.handler import Handler
+
+from contextlib import closing
+import socket
+import struct
+import time
+
+DEFAULT_SERIAL_PORT = "/dev/ttyUSB0"
+DEFAULT_SERIAL_BAUD = 1000000
+
+DEFAULT_UDP_ADDRESS = "127.0.0.1"
+DEFAULT_UDP_PORT    = 13320
+
+DEFAULT_LOG_FILENAME = time.strftime("sbp-%Y%m%d-%H%M%S.log")
+
+def get_args():
+  """
+  Get and parse arguments.
+  """
+  import argparse
+  parser = argparse.ArgumentParser(description="Swift Navigation SBP Example.")
+  parser.add_argument("-s", "--serial-port",
+                      default=[DEFAULT_SERIAL_PORT], nargs=1,
+                      help="specify the serial port to use.")
+  parser.add_argument("-b", "--baud",
+                      default=[DEFAULT_SERIAL_BAUD], nargs=1,
+                      help="specify the baud rate to use.")
+  parser.add_argument("-a", "--address",
+                      default=[DEFAULT_UDP_ADDRESS], nargs=1,
+                      help="specify the serial port to use.")
+  parser.add_argument("-p", "--udp-port",
+                      default=[DEFAULT_UDP_PORT], nargs=1,
+                      help="specify the baud rate to use.")
+  return parser.parse_args()
+
+def send_udp_callback_generator(udp, args):
+  def send_udp_callback(msg):
+    s = ""
+    s += struct.pack("<BHHB", 0x55, msg.msg_type, msg.sender, msg.length)
+    s += msg.payload
+    s += struct.pack("<H", msg.crc)
+    udp.sendto(s, (args.address[0], args.udp_port[0]))
+
+  return send_udp_callback
+
+def main():
+  args = get_args()
+
+  with PySerialDriver(args.serial_port[0], args.baud[0]) as driver:
+    with Handler(driver.read, driver.write) as handler:
+      with closing(socket.socket(socket.AF_INET, socket.SOCK_DGRAM)) as udp:
+        handler.add_callback(send_udp_callback_generator(udp, args))
+        handler.start()
+
+        try:
+          while True:
+            time.sleep(0.1)
+        except KeyboardInterrupt:
+          pass
+
+if __name__ == "__main__":
+  main()
+