I have made up a DB9 connector with connections to an Arduino. I am using pins 1 to 4 on the connector. On the Arduino I have a small program which writes out a series of digital HIGH signals to the connector's pins. On the Commodore 64 I have a simple Basic program that reads the state of joystick port #1. The problem is that the Commodore 64 is not registering a state change on the port, it continually prints out a value of 255. I know the port works because I connected a joystick to it and tested it.
What am I doing wrong? Do I need to boost the current from the Arduino to the joystick port with a MOSFET, or a relay? Are the pins on the joystick port active HIGH, or active LOW.