# Creates a new signal calculated from an existing signal
# The new signal can be used in Trace, Data and Graph view

# Script takes incoming message from desired channel
# Creates a new message, copies original message data to it
# Calculates FIR filtered data and adds it to the new message
# Sends new message to virtual channel and original message goes through as normal

meanValue = 0

# Function that handles all incoming messages
def recvFunc(canmsg):
    if (canmsg.Channel == 1 and canmsg.Id == 385):
        global meanValue    
        newmsg = CanMsg() # New message to be modified 
        
        # Change to 16 bit for data calculations
        currentValue = (canmsg.Data[1]<<8)|canmsg.Data[0]
	
        # Support negative values
        if currentValue >= 32768:
            currentValue = -65536 + currentValue

        # Calculates FIR filtered value
        meanValue = (5 * meanValue + currentValue)/6
    
        # Copy information from original message to new message
        newmsg.Id = canmsg.Id
        newmsg.Channel = canmsg.Channel
        newmsg.Dlc = canmsg.Dlc
        newmsg.TimeStamp = canmsg.TimeStamp
        newmsg.IsTxAck = canmsg.IsTxAck       
        newmsg.IsExtendedId = canmsg.IsExtendedId
        newmsg.IsRtr = canmsg.IsRtr
        newmsg.IsErrorFrame = canmsg.IsErrorFrame

        # Insert filtered data to new message
        newmsg.Data[1] = (meanValue >> 8) & 0xff
        newmsg.Data[0] = meanValue & 0xff

        ctapi.Send(2, newmsg) # Send new message to desired channel
        
    return True # Return True = original canmsg goes through also