I am trying to make an audio game for the ER-301. I have some questions

So I make games as a hobby, often 2d sidescrollers. I was thinking about how I would make an audio game to be played on the ER-301.

My concept right now is a game of keep up where a pitch goes up and down representing a ball. Each player would press a button to bounce the ball upwards. If the ball/pitch gets low enough you can’t bounce it and the game is lost.

I have a good idea of how to tell if the ball is in play or not using a sample scanner against the pitch. If the pitch is low enough the sample scanner will return 0v and that number will be used as a vca for the input triggers.

The thing I can’t quite figure out is how to modulate the pitch of the ball as if it is rising and falling. In a traditional game I have made I have a variable for velocity and subtract a constant every frame for gravity. When you bounce the ball you add a constant for one frame only to reverse the direction of the ball. Then you add the velocity to the y position of the ball every frame. This way if you hit the ball high in its arc it would go even higher.

Basically my problem is that I don’t know how to precisely add two numbers together every cycle of a clock.

If anyone knows how I should go about this, or has any ideas that are less influenced by traditional game programming, I would appreciate it.


This sounds like an Offset unit followed by a Sample-and-Hold unit.

That is interesting. I started thinking about it as a loop so I tried using an delay with it’s feedback going through an very slightly negative offset. With just that I could get the gravity. The only problem is that after a bunch of feedback the signal wouldn’t maintain a pitch when the offset was 0v. A slew limiter helped but the pitch was still wavering a bit.