PIC 18F4550 and MCP23017

[DaveC3]

I think you have a typo error

GPINTENA con &00 should be GPINTENA con $00

Try that

Dave

You also need to initialize the MCP23017

InitMPC23017:
Pause 100
'#############  PORTA
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IOCONA,IOCONSETA]
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IODIRA,$0]          'PortA inputs
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IOLATA,$FF]            'PortA = 0
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IPOLA,0]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[DEFVALA,0]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[GPPUA,$FF]           'pull-ups enabled
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[INTCONA,0]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[GPINTENA,$FF]        'interupt on change
'##############  PORTB
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IOCONB,IOCONSETB]
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IODIRB,0]
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IOLATB,$FF]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IPOLB,0]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[DEFVALB,0]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[INTCONB,0]
'i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[GPINTENB,0]
return
ReInitPortA:
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IOCONA,IOCONSETA]
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[IODIRA,$FF] 
i2cwrite  PortA.0,PortA.1,IO_EXP0WR,[GPPUA,$FF]           'pull-ups enabled

return