I developed the Modder's Trigger Interface so my sound boards could offer power and sound call information to connected mods. This page provides sufficient technical details via an example to facilitate third party development of modifications for games using my sound boards. The example mod reacts to two sound calls - with sound 6 the mod sequentially flashes six LEDs arranged in a rectangle and sound 8 causes all six LEDs are simultaneously flashed once. In ROM 1, sound 6 is the tilt warning sound and sound 8 is the explosion sound. This entire example is published under GPLv3 to maximize usability (in whole or in part) and/or revision by private individuals and commercial mod makers.
The Modder's Trigger Interface implemented on my sound board is a non-standard use of a USB connector. It provides 500mA of power at 5v DC across pins 1 and 4 of the USB 'A' port. Additionally the 'D+' line delivers a "listen" signal and the 'D-' line delivers a "countme" signal. Each sound call is decoded by counting the "countme" line transitions while the "listen" signal is low. Note that both listen and countme are 3.3v signals. These oscilloscope captures show two examples - The first decodes to sound 1; the second decodes to sound 8.
The example hardware is an ATtiny841 connected with the countme signal wired to pin PB0 and the listen pin wired to pin PB1. The seven LEDs are each wired in series with a current limit resistor from +5v to ATtiny841 pins PA0 through PA6. The ATtiny-based mod is powered via the nonstandard USB Modder's Trigger Interface and the 3.3v signal lines properly.
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