Adaptive Triggers on PC Without Buying an App
The DualSense's best feature mostly doesn't work on PC. I wrote a small tool that drives the triggers over Bluetooth from the public HID protocol.
On a PS5, the DualSense's adaptive triggers push back: a brake pedal firms up, a gun has a click point. On PC most games don't use them, and the popular fix is a paid app. I wanted to see how far the public documentation could take me.
The controller's output report layout is documented by open-source drivers, so DualTrigger builds that report itself and sends it over Bluetooth. Two details cost me the most time. Over Bluetooth the report is 78 bytes with a CRC32 at the end, seeded with 0xA2, and if the checksum is wrong the controller silently ignores the whole thing. And Windows drops output reports that aren't padded to the device's declared output length, again without an error. Until both were right, nothing happened at all.
Once the triggers responded, the rest was mapping. The tool watches which game is in the foreground and loads that game's profile, built from my launcher's library. Racing games get a smart mode that reads how far the trigger is pressed: the brake firms up, and pressing past a threshold sets off an ABS-style pulse. Shooters get a click point and a little recoil.
What I took away: when hardware ignores you instead of returning an error, the bug is almost always in the framing, meaning the length, the checksum or the report ID, not in the payload you meant to send.