Edit Port Form: Kempston Joystick 2, Joystick I/O

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For READ functionality the details are identical with {{PortNo|$xx1F}} Since core3.1.5 there is option to do I/O operations through joystick ports. The I/O mode should be set by writing this port first followed by enabling I/O mode on the joysticks with a write to {{NextRegNo|$05}}. The WRITE functionality: {| class="wikitable" ! Bit !! Function |- | 7-6 || select I/O mode: %00 = bit bang, %01 = clock, %10 = uart |- | 5 || Reserved must be 0 |- | 4 || 0 to read "input" part of I/O from left joystick socket, 1 to read from right joystick socket The program can still change the active joystick via bit 4 of port 0x37 at any time but for uart mode this should be done during a quiet time in communication. Any output always appears on pin 7 of both joystick connectors. |- | 3-1 || Reserved must be 0 |- | 0 || parameter bit controls state of pin 7 on both joystick connectors: bit bang: bit 0 is copied to pin 7<br> clock: 0 = place slow clock on pin 7 (Fsys/2048 = 13.672kHz), 1 = place fast clock on pin 7 (Fsys/8 = 3.5MHz) &dagger;<br> uart: 0 = redirect esp uart to joystick connector, 1 = redirect pi uart to joystick connector (Tx appears on pin 7, Rx taken from pin 9) |} &dagger; A runt clock pulse may appear in the first cycle, minimum pulse width is 1/Fsys = 35.7ns

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