Input Noise

[PJALM]

Here is the interrupt handler:

'-------------------------------------------------------------------------------
' Interrupt Handler
'-------------------------------------------------------------------------------
    DISABLE INTERRUPT                        ' No interrupts past this point
Main_Interrupt_Handler:

    '---------------------------------------------------------------------------
    ' PortB.0 Interrupt, Motor RPM Counter
    '---------------------------------------------------------------------------
	IF INTCON.1 = 1 THEN
        IF Calibrating = 1 THEN
            Total_Pulses = Total_Pulses + 1
        ELSE
            IF System_Calibrated = 1 THEN
                New_Position_Counter = New_Position_Counter + 1

                IF New_Position_Counter >= (Pulses_Per_Position + Temp_Pulses) THEN
                    SELECT CASE Current_Direction
                        CASE Forward_Dir
                            Current_Position = Current_Position + 1
                            IF Current_Position > Total_Positions THEN
                                Current_Position = 1
                            ENDIF
                        CASE Reverse_Dir
                            Current_Position = Current_Position - 1
                            IF Current_Position = 0 THEN
                                Current_Position = Total_Positions
                            ENDIF
                    END SELECT

                    DEBUG 13, 10, "[ Position Change ] Current Position: ", DEC Current_Position, 13, 10
                    
                    New_Position_Counter = 0
                    Temp_Pulses = 0
                ENDIF
            ENDIF
        ENDIF
            INTCON.1 = 0
	ENDIF 
    '---------------------------------------------------------------------------


        
    '---------------------------------------------------------------------------
	' PortB.1 Interrupt, Position 1 Sensor
    '---------------------------------------------------------------------------
	IF INTCON3.0 = 1 THEN
        DEBUG 13, 10, "[ INTERRUPT ] Home Position Detected", 13, 10
            Pos1Found = 1
            New_Position_Counter = 0
            Temp_Pulses = 0
            Current_Position = 1
	    INTCON3.0 = 0
	ENDIF
    '---------------------------------------------------------------------------



    '---------------------------------------------------------------------------
    ' PortB.2 Interrupt, Fault Relay Input
    '---------------------------------------------------------------------------
    IF INTCON3.1 = 1 THEN
        DEBUG 13, 10, "[ INTERRUPT ] AC Invertor Fault Detected", 13, 10
        AC_Fault_Detected = 1
        INTCON3.1 = 0
    ENDIF
    '---------------------------------------------------------------------------
    


    '---------------------------------------------------------------------------
    ' USART Receive Interrupt
    '---------------------------------------------------------------------------
    IF PIR1.5 = 1 THEN
        'DEBUG 13, 10, "[ INTERRUPT ] USART Receive", 13, 10

        HSERIN [RS485_B0]

        SELECT CASE RS485_B0
            CASE RS485_STX
                RS485_Receiving_Data = 1
                RS485_Bytes_Received = 0
                FOR i = 1 TO RS485_Buffer_Size
                    RS485_Data_Buffer[i] = 0
                NEXT
                
            CASE RS485_ETX
                RS485_Receiving_Data = 0
                
                RS485_To_Address = RS485_Data_Buffer(0)
                RS485_Command = RS485_Data_Buffer(1)
                RS485_Parameter.HighByte = RS485_Data_Buffer(2)
                RS485_Parameter.LowByte = RS485_Data_Buffer(3)
                RS485_From_Address = RS485_Data_Buffer(4)
                
                RS485_Parameter = RS485_Parameter - 10
                
            CASE ELSE
                IF RS485_Receiving_Data = 1 THEN
                    RS485_Data_Buffer(RS485_Bytes_Received) = RS485_B0
                    RS485_Bytes_Received = RS485_Bytes_Received + 1
                ENDIF
        END SELECT
        PIR1.5 = 0
    ENDIF
    '---------------------------------------------------------------------------

        
IntDone:
	RESUME					' Return to main program
    ENABLE INTERRUPT
'-------------------------------------------------------------------------------

[Bruce]

This looks OK to me except for PIR1.5 = 0.

The USART receive interrupt flag bit can only be cleared by reading RCREG
until the buffer is empty. You're reading this only once in your int handler.

If you receive more than a single byte of data it can cause problems. I would
test the flag again before exiting this particular int handler sub-routine.

I don't think this is causing the problem you're seeing, but it could be one if
you're expecting PIR1.5 = 0 to clear the USART interrupt flag.

What happens if you remove the encoder, and replace it with a push-button
switch?

Does pressing the switch to simulate the encoder logic on the int0 input pin
work?

If it works then I would have to suspect an isolation problem.

[PJALM]

Bruce, putting the switch works fine so I also suspect its an isolation problem. I am going to try your sujestions and build a second power supply.

[PJALM]

I finally got it fixed.

It turns out that the conduit I was using is made of aluminum not steel and for some reason it was not good enough to shield the 3 phase power cables to the motor. I changed it to steel and it works fine now.

I also fixed the isolation problem thanks to your sugestions Bruce.

Thanks everyone.