diff --git a/src/drivers/px4flow/i2c_frame.h b/src/drivers/px4flow/i2c_frame.h
index ec8a5e1fda..2db240e35e 100644
--- a/src/drivers/px4flow/i2c_frame.h
+++ b/src/drivers/px4flow/i2c_frame.h
@@ -34,47 +34,48 @@
 /**
  * @file i2c_frame.h
  * Definition of i2c frames.
+ * There are different I2C readouts available: i2c_frame and i2c_integral_frame.
+ * The ic2_frame can be requested via the register 0x0, the i2c_integral_frame via 0x16.
+ *
  * @author Thomas Boehm <thomas.boehm@fortiss.org>
  * @author James Goppert <james.goppert@gmail.com>
  */
 
-#ifndef I2C_FRAME_H_
-#define I2C_FRAME_H_
+#pragma once
 
 #include <inttypes.h>
 
 typedef  struct i2c_frame {
-	uint16_t frame_count;
-	int16_t pixel_flow_x_sum;
-	int16_t pixel_flow_y_sum;
-	int16_t flow_comp_m_x;
-	int16_t flow_comp_m_y;
-	int16_t qual;
-	int16_t gyro_x_rate;
-	int16_t gyro_y_rate;
-	int16_t gyro_z_rate;
-	uint8_t gyro_range;
-	uint8_t sonar_timestamp;
-	int16_t ground_distance;
+	uint16_t frame_count;       /**< counts created I2C frames [#frames] */
+	int16_t pixel_flow_x_sum;   /**< latest x flow measurement in pixels*10 [pixels] */
+	int16_t pixel_flow_y_sum;   /**< latest y flow measurement in pixels*10 [pixels] */
+	int16_t flow_comp_m_x;      /**< x velocity*1000 [meters/sec] */
+	int16_t flow_comp_m_y;      /**< y velocity*1000 [meters/sec] */
+	int16_t qual;               /**< Optical flow quality / confidence [0: bad, 255: maximum quality] */
+	int16_t gyro_x_rate;        /**< latest gyro x rate [rad/sec] */
+	int16_t gyro_y_rate;        /**< latest gyro y rate [rad/sec] */
+	int16_t gyro_z_rate;        /**< latest gyro z rate [rad/sec] */
+	uint8_t gyro_range;         /**< gyro range [0 .. 7] equals [50 deg/sec .. 2000 deg/sec] */
+	uint8_t sonar_timestamp;    /**< time since last sonar update [milliseconds] */
+	int16_t ground_distance;    /**< Ground distance in meters*1000 [meters]. Positive value: distance known. Negative value: Unknown distance */
 } i2c_frame;
 
 #define I2C_FRAME_SIZE (sizeof(i2c_frame))
 
 
 typedef struct i2c_integral_frame {
-	uint16_t frame_count_since_last_readout;
-	int16_t pixel_flow_x_integral;
-	int16_t pixel_flow_y_integral;
-	int16_t gyro_x_rate_integral;
-	int16_t gyro_y_rate_integral;
-	int16_t gyro_z_rate_integral;
-	uint32_t integration_timespan;
-	uint32_t sonar_timestamp;
-	uint16_t ground_distance;
-	int16_t gyro_temperature;
-	uint8_t qual;
+	uint16_t frame_count_since_last_readout; /**< number of flow measurements since last I2C readout [#frames] */
+	int16_t pixel_flow_x_integral;           /**< accumulated flow in radians*10000 around x axis since last I2C readout [rad*10000] */
+	int16_t pixel_flow_y_integral;           /**< accumulated flow in radians*10000 around y axis since last I2C readout [rad*10000] */
+	int16_t gyro_x_rate_integral;            /**< accumulated gyro x rates in radians*10000 since last I2C readout [rad*10000] */
+	int16_t gyro_y_rate_integral;            /**< accumulated gyro y rates in radians*10000 since last I2C readout [rad*10000] */
+	int16_t gyro_z_rate_integral;            /**< accumulated gyro z rates in radians*10000 since last I2C readout [rad*10000] */
+	uint32_t integration_timespan;           /**< accumulation timespan in microseconds since last I2C readout [microseconds] */
+	uint32_t sonar_timestamp;                /**< time since last sonar update [microseconds] */
+	uint16_t ground_distance;                /**< Ground distance in meters*1000 [meters*1000] */
+	int16_t gyro_temperature;                /**< Temperature * 100 in centi-degrees Celsius [degcelsius*100] */
+	uint8_t qual;                            /**< averaged quality of accumulated flow values [0:bad quality;255: max quality] */
 } i2c_integral_frame;
 
 #define I2C_INTEGRAL_FRAME_SIZE (sizeof(i2c_integral_frame))
 
-#endif /* I2C_FRAME_H_ */