From 5c15d743944f0ba68093580474cfbf8d759f6663 Mon Sep 17 00:00:00 2001
From: Aubrey Hesselgren <[EMAIL REDACTED]>
Date: Mon, 19 Jan 2026 14:54:04 -0800
Subject: [PATCH] Fix Horipad bluetooth gyro stutter issues using simulated
sensor timing approach (based on packet rate observation)
By observation: wired is 250hz/4000ms, and bluetooth is 120hz/8333ms for IMU sensor.
---
src/joystick/hidapi/SDL_hidapi_steam_hori.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/src/joystick/hidapi/SDL_hidapi_steam_hori.c b/src/joystick/hidapi/SDL_hidapi_steam_hori.c
index 0519612348565..d92634d54accd 100644
--- a/src/joystick/hidapi/SDL_hidapi_steam_hori.c
+++ b/src/joystick/hidapi/SDL_hidapi_steam_hori.c
@@ -51,6 +51,8 @@ typedef struct
Uint8 last_state[USB_PACKET_LENGTH];
Uint64 sensor_ticks;
Uint32 last_tick;
+ Uint64 simulated_sensor_step_ns;
+ Uint64 simulated_sensor_time_stamp;
bool wireless;
bool serial_needs_init;
} SDL_DriverSteamHori_Context;
@@ -126,9 +128,13 @@ static bool HIDAPI_DriverSteamHori_OpenJoystick(SDL_HIDAPI_Device *device, SDL_J
HIDAPI_DriverSteamHori_UpdateDevice(device);
}
- SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, 250.0f);
- SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, 250.0f);
+ const float sensorupdaterate = ctx->wireless ? 120.0f : 250.0f;
+ SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, sensorupdaterate);
+ SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, sensorupdaterate);
+
+ const Uint64 sensorupdatestep_ms = ctx->wireless ? 8333 : 4000; // Equivalent to 120hz / 250hz respectively
+ ctx->simulated_sensor_step_ns = SDL_US_TO_NS(sensorupdatestep_ms);
return true;
}
@@ -313,7 +319,11 @@ static void HIDAPI_DriverSteamHori_HandleStatePacket(SDL_Joystick *joystick, SDL
ctx->sensor_ticks += delta;
/* Sensor timestamp is in 1us units, but there seems to be some issues with the values reported from the device */
- sensor_timestamp = timestamp; // if the values were good we would call SDL_US_TO_NS(ctx->sensor_ticks);
+ // sensor_timestamp = timestamp; // if the values were good we would call SDL_US_TO_NS(ctx->sensor_ticks);
+
+ /* New approach - simulate a fixed rate of 250hz (from observation). This reduces stutter from dropped/racing bluetooth packets.*/
+ ctx->simulated_sensor_time_stamp += ctx->simulated_sensor_step_ns;
+ sensor_timestamp = ctx->simulated_sensor_time_stamp;
const float accelScale = SDL_STANDARD_GRAVITY * 8 / 32768.0f;
const float gyroScale = DEG2RAD(2048);