Tools: added CAN playback tool

uses frames from lua CAN bus capture and plays back for driver
development

Tools/scripts/CAN/CAN_playback.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+'''
+playback a set of CAN frames from libraries/AP_Scripting/examples/CAN_logger.lua onto a CAN bus
+'''
+
+import dronecan
+import time
+import sys
+import threading
+from pymavlink import mavutil
+from dronecan.driver.common import CANFrame
+
+
+# get command line arguments
+from argparse import ArgumentParser
+parser = ArgumentParser(description='CAN playback')
+parser.add_argument("logfile", default=None, type=str, help="logfile")
+parser.add_argument("canport", default=None, type=str, help="CAN port")
+
+args = parser.parse_args()
+
+print("Connecting to %s" % args.canport)
+driver = dronecan.driver.make_driver(args.canport)
+
+print("Opening %s" % args.logfile)
+mlog = mavutil.mavlink_connection(args.logfile)
+
+tstart = time.time()
+first_tstamp = None
+
+while True:
+    m = mlog.recv_match(type='CANF')
+
+    if m is None:
+        print("Rewinding")
+        mlog.rewind()
+        tstart = time.time()
+        first_tstamp = None
+        continue
+
+    if first_tstamp is None:
+        first_tstamp = m.TimeUS
+    dt = time.time() - tstart
+    dt2 = (m.TimeUS - first_tstamp)*1.0e-6
+    if dt2 > dt:
+        time.sleep(dt2 - dt)
+    data = [m.B0, m.B1, m.B2, m.B3, m.B4, m.B5, m.B6, m.B7]
+    data = data[:m.DLC]
+    fid = m.Id
+    is_extended = (fid & (1<<31)) != 0
+    driver.send(fid, data, extended=is_extended, canfd=False)
+    print(m)