Improve PDO periodic transmit accuracy

Author: christiansandberg

canopen/pdo.py

@@ -1,3 +1,4 @@
+import sys
 import time
 import threading
 import math
@@ -14,6 +15,17 @@
 RTR_NOT_ALLOWED = 1 << 30
 
 
+if hasattr(time, "perf_counter"):
+    # Choose time.perf_counter if available
+    timer = time.perf_counter
+elif sys.platform == "win32":
+    # On Windows, the best timer is time.clock
+    timer = time.clock
+else:
+    # On most other platforms the best timer is time.time
+    timer = time.time
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -363,13 +375,14 @@ def wait_for_reception(self, timeout=10):
 
     def _periodic_transmit(self):
         while not self.stop_event.is_set():
-            start = time.time()
+            start = timer()
             try:
                 self.transmit()
             except CanError as error:
                 print(str(error))
-            time_left = self.period - (time.time() - start)
-            time.sleep(max(time_left, 0.0))
+            time_left = self.period - (timer() - start)
+            if time_left > 0:
+                time.sleep(time_left)
 
 
 class Variable(common.Variable):

canopen/version.py

@@ -1,2 +1,2 @@
 
-__version__ = "0.4.0.dev5"
+__version__ = "0.4.0.dev6"