Bluetooth interface adds rumble feedback to Commodore 64 games

Nothing says “1980s gaming” better than a black joystick with a single red fire button. But if you prefer better ergonomics, you can connect modern gamepads to your retro computers with a variety of modern to classic interface adapters. These typically only support the directional pad and one or two action buttons, leaving out modern features like motion control and haptic feedback.

It’s a bit of a shame, because we think it would be pretty cool to feel that shock in our hands every time Pitfall Harry drowns in quicksand or Frogger gets hit by traffic. We are therefore happy to announce that [Ricardo Quesada] has decided to add rumble functionality to the Bluetooth-to-Joystick-port interface on which he is working. He demonstrates the feature on his Commodore 64 in the embedded video after the break.

Naturally, any software must be adapted to support haptic feedback, but a trickier problem turned out to be the hardware: the joystick ports are input devices only and therefore cannot send ‘turn on’ signals. rumble” to connected gamepads. [Ricardo] found a clever way around this, using the analog inputs on the joystick port which were typically used for paddle-type controllers.

The analog-to-digital converter inside the computer works by applying a pulse signal to the analog port and measuring the time it takes to discharge a capacitor. The modern gamepad interface simply detects if these pulses are present; they can be enabled or disabled via software by toggling the analog readout on the joystick port. This way, the joystick port can be used to send a single bit of information to any device connected to it.

[Ricardo] patches developed for Rambo: First Blood Part II and Lake Geneva to activate the rumble feature. He describes the process in detail in his blog post, which should make it easy for anyone familiar with the 6502 machine code to add rumble support to their favorite games.

The adapter works with a variety of retro systems that use the Atari-style joystick interface, but if you’re an Apple II user, you might want to look at this Raspberry Pi-based project that interfaces with its joystick interface no standard. If you like wireless gaming in general, be sure to also check out our history of wireless game controllers.