The standard to enhanced joystick ports adapter for the Atari ST

[sporniket]

hardware part : https://github.com/sporniket/atari-st-mod-enhanced-to-standard-joystick-ports-adapter--hardware

The standard to enhanced joystick ports adapter for the Atari ST allows all the members of the Atari ST family of vintage computers (from the 1980~2000 era) to make use of the Atari Jaguar game controller (and hopefully, of the Team Tap adapter as well). It is made of :

• A PCB project, hosting a raspberry pico standard development board that will watch an enhanced joystick port on one side, and send joystick events through standard joystick ports of the Atari ST on the other side. A bypass switch allows to plug regular mouse/joysticks for legacy games and regular work.
• A firmware project for said raspberry pico.
• Some sample 68k assembly routines to handle joystick events to reconstruct the single Jaguar game controller state and the multiple Jaguar controllers states through TeamTap.

Theory of operation

• The raspberry pico probe the Jaguar game controller or the Team Tap extension as much as possible.
• The raspberry pico send changes through both the standard joystick ports ; 10 times per seconds, the full state of the controller is sent.
• On the host Atari ST computer, a custom assembly routine is tasked to get the joysticks states and map them into the Jaguar controller(s) states.

[sporniket]

Basic test program

Display 4 stylised Jaguar controllers, and highlight activated control (dpad direction, buttons, numeric pad)

Basic demonstration

Program for assessing actual responsiveness in plausible gameplay :

• Battle arena for 4 players (sprites '1' to '4')
• Button A : shield (prevent 2 hit) points, duration 1 seconds, cooldown 4 seconds)
• Button B : slash (3 hit points)
• Button C : magic missile (2 hit points), consume 1 mana
• Button '1' : drink small Health potion
• Button '2' : drink small Mana potion
• Button '4' : drink big Health potion
• Button '5' : drink big Mana potion

Player :

• 10 HP (can be set : 7/10/13) ; 0 ⇒ KO, respawn after 1 second in safe area
• 10 MP (can be set : 7/10/13) ; 0 ⇒ no more magic missiles

Drops :

• small Health potion : +3 HP
• big Health potion : +10 HP
• small Mana potion : +3 MP
• big Mana potion : +10 MP
• elixir : Restore full HP/MP