On 5/1/21 6:24 am, Jim Anderson wrote:
As I recall, the way it worked was that the five switches (directional switches and fire) were wired to the first five output bits, and the common return from all five switches was wired to BUSY. To poll the joystick you'd cycle through outputting ASCII 1, 2, 4, 8, and 16, and read BUSY each time. Whichever bits resulted in assertion of BUSY meant that switch was currently closed.
Probably need diodes in there as well, to stop from inadvertantly driving an output low and high at the same time if the joystick had more than one switch closed (e.g. up and fire). Cheers, --dt
