AP_HAL: Enable optical flow onboard for BBBMINI

libraries/AP_HAL/AP_HAL_Boards.h

@@ -309,6 +309,21 @@
 #define HAL_INS_DEFAULT HAL_INS_MPU9250
 #define HAL_BARO_DEFAULT HAL_BARO_MS5611_SPI
 #define HAL_COMPASS_DEFAULT HAL_COMPASS_AK8963_MPU9250
+#define HAL_OPTFLOW_ONBOARD_VDEV_PATH "/dev/video0"
+#define HAL_OPTFLOW_ONBOARD_SENSOR_WIDTH 320
+#define HAL_OPTFLOW_ONBOARD_SENSOR_HEIGHT 240
+#define HAL_OPTFLOW_ONBOARD_OUTPUT_WIDTH 64
+#define HAL_OPTFLOW_ONBOARD_OUTPUT_HEIGHT 64
+#define HAL_OPTFLOW_ONBOARD_CROP_WIDTH 240
+#define HAL_OPTFLOW_ONBOARD_CROP_HEIGHT 240
+#define HAL_OPTFLOW_ONBOARD_NBUFS 8;
+#define HAL_FLOW_PX4_MAX_FLOW_PIXEL 4
+#define HAL_FLOW_PX4_BOTTOM_FLOW_FEATURE_THRESHOLD 30
+#define HAL_FLOW_PX4_BOTTOM_FLOW_VALUE_THRESHOLD 5000
+/* ELP-USBFHD01M-L21
+ * focal length 2.1 mm, pixel size 3 um
+ * 240x240 crop rescaled to 64x64 */
+#define HAL_FLOW_PX4_FOCAL_LENGTH_MILLIPX (3.0 / (2.1 * 2.0 * 240 / 64))
 #define HAL_GPIO_A_LED_PIN        61
 #define HAL_GPIO_B_LED_PIN        48
 #define HAL_GPIO_C_LED_PIN        117