From 1e886c8a2f0068affe878374ed942668ca14890c Mon Sep 17 00:00:00 2001
From: Aubrey Hesselgren <[EMAIL REDACTED]>
Date: Fri, 13 Jun 2025 22:25:31 -0700
Subject: [PATCH] 8 bitdo polling rate corrections (#13221)
Gathered correct IMU polling rate in wired mode for good gyro synchronization.
Wireless: different models had different amounts of Bluetooth packet loss.
USB_PRODUCT_8BITDO_ULTIMATE2_WIRELESS: Solid 120hz over bluetooth (note: only appears via).
USB_PRODUCT_8BITDO_PRO_2_BT: Lossy - 80-90hz registered.
SB_PRODUCT_8BITDO_SN30_PRO_BT & USB_PRODUCT_8BITDO_SN30_PRO_BT: Very Lossy - 60-90hz registered
---
src/joystick/hidapi/SDL_hidapi_8bitdo.c | 36 ++++++++++++++++++++-----
1 file changed, 30 insertions(+), 6 deletions(-)
diff --git a/src/joystick/hidapi/SDL_hidapi_8bitdo.c b/src/joystick/hidapi/SDL_hidapi_8bitdo.c
index 170eb66638eab..10f19fc279df9 100644
--- a/src/joystick/hidapi/SDL_hidapi_8bitdo.c
+++ b/src/joystick/hidapi/SDL_hidapi_8bitdo.c
@@ -48,8 +48,6 @@ enum
#define SDL_8BITDO_BT_REPORTID_SDL_REPORTID 0x01
#define ABITDO_ACCEL_SCALE 4096.f
-#define ABITDO_SENSOR_POLLING_RATE 125.f
-#define SENSOR_INTERVAL_NS 8000000ULL
#define ABITDO_GYRO_MAX_DEGREES_PER_SECOND 2000.f
typedef struct
@@ -69,7 +67,8 @@ typedef struct
float accelScale;
float gyroScale;
Uint8 last_state[USB_PACKET_LENGTH];
- Uint64 sensor_timestamp; // Nanoseconds. Simulate onboard clock. Advance by known rate: SENSOR_INTERVAL_NS == 8ms = 125 Hz
+ Uint64 sensor_timestamp; // Nanoseconds. Simulate onboard clock. Different models have different rates vs different connection styles.
+ Uint64 sensor_timestamp_interval;
} SDL_Driver8BitDo_Context;
#pragma pack(push,1)
@@ -217,6 +216,27 @@ static void HIDAPI_Driver8BitDo_SetDevicePlayerIndex(SDL_HIDAPI_Device *device,
{
}
+static Uint64 HIDAPI_Driver8BitDo_GetIMURateForProductID(SDL_HIDAPI_Device *device)
+{
+ // TODO: If sensor time stamp is sent, these fixed settings from observation can be replaced
+ switch (device->product_id) {
+ // Note, This is estimated by observation of Bluetooth packets received in the testcontroller tool
+ case USB_PRODUCT_8BITDO_SN30_PRO_BT:
+ case USB_PRODUCT_8BITDO_SF30_PRO_BT:
+ return 90; // Observed to be anywhere between 60-90 hz. Possibly lossy in current state
+ case USB_PRODUCT_8BITDO_SF30_PRO:
+ case USB_PRODUCT_8BITDO_SN30_PRO:
+ return 100;
+ case USB_PRODUCT_8BITDO_PRO_2:
+ case USB_PRODUCT_8BITDO_PRO_2_BT:// Note, labelled as "BT" but appears this way when wired. Observed bluetooth packet rate seems to be 80-90hz
+ return (device->is_bluetooth ? 85 : 100);
+ case USB_PRODUCT_8BITDO_ULTIMATE2_WIRELESS:
+ default:
+ return 120;
+ break;
+ }
+}
+
#ifndef DEG2RAD
#define DEG2RAD(x) ((float)(x) * (float)(SDL_PI_F / 180.f))
#endif
@@ -242,9 +262,13 @@ static bool HIDAPI_Driver8BitDo_OpenJoystick(SDL_HIDAPI_Device *device, SDL_Joys
joystick->nhats = 1;
if (ctx->sensors_supported) {
- SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, ABITDO_SENSOR_POLLING_RATE);
- SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, ABITDO_SENSOR_POLLING_RATE);
+ // Different 8Bitdo controllers in different connection modes have different polling rates.
+ const Uint64 imu_polling_rate = HIDAPI_Driver8BitDo_GetIMURateForProductID(device);
+ ctx->sensor_timestamp_interval = SDL_NS_PER_SECOND / imu_polling_rate;
+
+ SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_GYRO, (float)imu_polling_rate);
+ SDL_PrivateJoystickAddSensor(joystick, SDL_SENSOR_ACCEL, (float)imu_polling_rate);
ctx->accelScale = SDL_STANDARD_GRAVITY / ABITDO_ACCEL_SCALE;
// Hardware senses +/- N Degrees per second mapped to +/- INT16_MAX
@@ -525,7 +549,7 @@ static void HIDAPI_Driver8BitDo_HandleStatePacket(SDL_Joystick *joystick, SDL_Dr
// 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;
+ ctx->sensor_timestamp += ctx->sensor_timestamp_interval;
// This device's IMU values are reported differently from SDL
// Thus we perform a rotation of the coordinate system to match the SDL standard.