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Fix IMU orientations for 8bitdo wireless 2 controller in bluetooth mode 

Fix IMU timing stamp - simulate the timing stamp from the controller hardware's perspective, as opposed to the receiving computer's perspective. Do this by advancing a time stamp by a fixed rate, based on observation of average rate over bluetooth.
This commit is contained in:
Aubrey Hesselgren 2025-04-09 10:46:41 -07:00 committed by Sam Lantinga
parent b0860fb0c2
commit 60fb1b5541
1 changed files with 33 additions and 12 deletions
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45
src/joystick/hidapi/SDL_hidapi_8bitdo.c
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@ -42,9 +42,8 @@ enum
SDL_GAMEPAD_NUM_8BITDO_BUTTONS,
};
#define ABITDO_GYRO_SCALE 14.2842f
#define ABITDO_ACCEL_SCALE 4096.f
#define SENSOR_INTERVAL_NS 8000000ULL
typedef struct
{
@ -63,6 +62,7 @@ typedef struct
float accelScale;
float gyroScale;
Uint8 last_state[USB_PACKET_LENGTH];
Uint64 sensor_timestamp; // Microseconds. Simulate onboard clock. Advance by known rate: SENSOR_INTERVAL_NS == 8ms = 125 Hz
} SDL_Driver8BitDo_Context;
#pragma pack(push,1)
@ -149,6 +149,10 @@ static void HIDAPI_Driver8BitDo_SetDevicePlayerIndex(SDL_HIDAPI_Device *device,
{
}
#ifndef DEG2RAD
#define DEG2RAD(x) ((float)(x) * (float)(SDL_PI_F / 180.f))
#endif
static bool HIDAPI_Driver8BitDo_OpenJoystick(SDL_HIDAPI_Device *device, SDL_Joystick *joystick)
{
SDL_Driver8BitDo_Context *ctx = (SDL_Driver8BitDo_Context *)device->context;
@ -163,12 +167,12 @@ static bool HIDAPI_Driver8BitDo_OpenJoystick(SDL_HIDAPI_Device *device, SDL_Joys
joystick->nhats = 1;
if (ctx->sensors_supported) {
SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, 250.0f);
SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, 250.0f);
SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, 125.0f);
SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, 125.0f);
ctx->accelScale = SDL_STANDARD_GRAVITY / ABITDO_ACCEL_SCALE;
ctx->gyroScale = SDL_PI_F / 180.0f / ABITDO_GYRO_SCALE;
ctx->gyroScale = DEG2RAD(2048) / INT16_MAX; // Hardware senses +/- 2048 Degrees per second mapped to +/- INT16_MAX
}
return true;
@ -357,15 +361,32 @@ static void HIDAPI_Driver8BitDo_HandleStatePacket(SDL_Joystick *joystick, SDL_Dr
float values[3];
ABITDO_SENSORS *sensors = (ABITDO_SENSORS *)&data[15];
sensor_timestamp = timestamp;
values[0] = (sensors->sGyroX) * (ctx->gyroScale);
values[1] = (sensors->sGyroZ) * (ctx->gyroScale);
values[2] = (sensors->sGyroY) * (ctx->gyroScale);
// Note: we cannot use the time stamp of the receiving computer due to packet delay creating "spiky" timings.
// The imu time stamp is intended to be the sample time of the on-board hardware.
// In the absence of time stamp data from the data[], we can simulate that by
// advancing a time stamp by the observed/known imu clock rate. This is 8ms = 125 Hz
sensor_timestamp = ctx->sensor_timestamp;
ctx->sensor_timestamp += SENSOR_INTERVAL_NS;
// This device's IMU values are reported differently from SDL
// Thus we perform a rotation of the coordinate system to match the SDL standard.
// By observation of this device:
// Hardware x is reporting roll (rotation about the power jack's axis)
// Hardware y is reporting pitch (rotation about the horizontal axis)
// Hardware z is reporting yaw (rotation about the joysticks' center axis)
values[0] = -sensors->sGyroY * ctx->gyroScale; // Rotation around pitch axis
values[1] = sensors->sGyroZ * ctx->gyroScale; // Rotation around yaw axis
values[2] = -sensors->sGyroX * ctx->gyroScale; // Rotation around roll axis
SDL_SendJoystickSensor(timestamp, joystick, SDL_SENSOR_GYRO, sensor_timestamp, values, 3);
values[0] = (sensors->sAccelX) * (ctx->accelScale);
values[1] = (sensors->sAccelZ) * (ctx->accelScale);
values[2] = (sensors->sAccelY) * (ctx->accelScale);
// By observation of this device:
// Accelerometer X is positive when front of the controller points toward the sky.
// Accelerometer y is positive when left side of the controller points toward the sky.
// Accelerometer Z is positive when sticks point toward the sky.
values[0] = -sensors->sAccelY * ctx->accelScale; // Acceleration along pitch axis
values[1] = sensors->sAccelZ * ctx->accelScale; // Acceleration along yaw axis
values[2] = -sensors->sAccelX * ctx->accelScale; // Acceleration along roll axis
SDL_SendJoystickSensor(timestamp, joystick, SDL_SENSOR_ACCEL, sensor_timestamp, values, 3);
}