show moving time, only after first movement

csc.py

@@ -5,7 +5,7 @@ import struct
 
 import sys
 import time
-from datetime import datetime
+from datetime import datetime, timedelta
 import os
 
 import pygame
@@ -22,7 +22,8 @@ class CadenceListener:
     wheelSpeed = 0
     crankSpeed = 0
     crankSpeedMax = 120
-    startTime = None
+    elapsedTime = None
+    firstMessage = True
 
     def getWheelSpeed(self):
         return self.wheelSpeed
@@ -35,13 +36,13 @@ class CadenceListener:
             offset = offset + 6
         if flags & 2:
             crankRevolutions,crankTime = struct.unpack('<HH', bytes(value)[offset:offset+4])        
-        # print(wheelrevs, wheeltime, crankrevs, cranktime)
-        if(not self.startTime):
+
+        if(self.firstMessage):
             self.prevCtime = crankTime
             self.prevWtime = wheelTime
             self.prevCrevs = crankRevolutions
             self.prevWrevs = wheelRevolutions
-            self.startTime = datetime.now()
+            self.firstMessage = False
             return
         
         # handle wraparound
@@ -62,14 +63,15 @@ class CadenceListener:
             self.prevCrevs = crankRevolutions
 
         if(wheelTime > self.prevWtime):
-            revs = ((wheelRevolutions - self.prevWrevs) /
-                    float(wheelTime - self.prevWtime))
+            millis = float(wheelTime - self.prevWtime)
+            self.rolling = True
+            revs = (wheelRevolutions - self.prevWrevs) / millis
+
             self.wheelSpeed = revs * 2205 * 3600 / 1024.0
-            print("wheel",
-                  (float(wheelTime - self.prevWtime)),
-                  self.wheelSpeed)
+            print("wheel", millis, self.wheelSpeed)
             self.prevWtime = wheelTime
             self.prevWrevs = wheelRevolutions
+            self.elapsedTime = (self.elapsedTime or 0) + (millis / 1024.0)
 
 class Biscuit:
     listener = CadenceListener()
@@ -95,8 +97,8 @@ class Biscuit:
                             (scale/16,scale + 20),
                             "{: 5.1f} rpm".format(self.listener.crankSpeed),
                             (0,255,0))
-        if self.listener.startTime !=  None:
-            runTime = datetime.now() - self.listener.startTime
+        if self.listener.elapsedTime !=  None:
+            runTime = timedelta(seconds=self.listener.elapsedTime)
             timelabel = str(runTime)[0:9]
         else:
             timelabel = datetime.now().strftime("%H:%M:%S")