AP_OpticalFlow: Add support for Linux

Add a Linux userspace driver for the PX4FLOW sensor.

libraries/AP_OpticalFlow/AP_OpticalFlow_Linux.cpp

@@ -0,0 +1,199 @@
+/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ *       AP_OpticalFlow_Linux.cpp - ardupilot library for the PX4Flow sensor.
+ *          inspired by the PX4Firmware code.
+ *      
+ *       @author: Víctor Mayoral Vilches
+ *
+ */
+
+#include <AP_HAL.h>
+#include "OpticalFlow.h"
+
+#define DEBUG 1
+#define RAW_READ 0
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+extern const AP_HAL::HAL& hal;
+
+AP_OpticalFlow_Linux::AP_OpticalFlow_Linux(OpticalFlow &_frontend) : 
+  OpticalFlow_backend(_frontend)
+{}
+
+
+void AP_OpticalFlow_Linux::init(void)
+{
+  uint8_t buff[22];
+
+  // get pointer to i2c bus semaphore
+  AP_HAL::Semaphore *i2c_sem = hal.i2c->get_semaphore();
+
+  // take i2c bus sempahore
+  if (!i2c_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
+      hal.scheduler->panic(PSTR("PX4FLOW: unable to get semaphore"));
+  }
+
+  // to be sure this is not a ll40ls Lidar (which can also be on
+  // 0x42) we check if a I2C_FRAME_SIZE byte transfer works from address
+  // 0. The ll40ls gives an error for that, whereas the flow
+  // happily returns some data
+  uint8_t val[I2C_FRAME_SIZE];
+  if (hal.i2c->readRegisters(I2C_FLOW_ADDRESS, 0, I2C_FRAME_SIZE, val))
+    hal.scheduler->panic(PSTR("ll40ls Lidar"));
+
+  i2c_sem->give();
+
+}
+
+int AP_OpticalFlow_Linux::read(optical_flow_s* report)
+{
+  // get pointer to i2c bus semaphore
+  AP_HAL::Semaphore *i2c_sem = hal.i2c->get_semaphore();
+
+  // take i2c bus sempahore
+  if (!i2c_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
+      hal.scheduler->panic(PSTR("PX4FLOW: unable to get semaphore"));
+  }
+
+
+  uint8_t val[I2C_FRAME_SIZE + I2C_INTEGRAL_FRAME_SIZE] = { 0 };
+
+#if RAW_READ
+  hal.console->printf_P(PSTR("PX4FLOW: RAW_READ"));
+  // Send the command to begin a measurement
+  uint8_t cmd = PX4FLOW_REG;
+  if (hal.i2c->write(I2C_FLOW_ADDRESS, 1, &cmd)){    
+    hal.console->printf_P(PSTR("PX4FLOW: Error while beginning a measurement"));
+    i2c_sem->give();
+    return 0;
+  }
+
+  // Perform the reading
+  if (PX4FLOW_REG == 0x00) {
+    if (hal.i2c->read(I2C_FLOW_ADDRESS, I2C_FRAME_SIZE + I2C_INTEGRAL_FRAME_SIZE, val)){
+      hal.console->printf_P(PSTR("PX4FLOW: Error while reading"));
+      i2c_sem->give();
+      return 0;
+    }
+  }
+
+  if (PX4FLOW_REG == 0x16) {
+    if (hal.i2c->read(I2C_FLOW_ADDRESS, I2C_INTEGRAL_FRAME_SIZE, val)){
+      hal.console->printf_P(PSTR("PX4FLOW: Error while reading"));
+      i2c_sem->give();
+      return 0;
+    }
+  }
+
+#else
+  // Perform the writing and reading in a single command
+  if (PX4FLOW_REG == 0x00) {
+    if (hal.i2c->readRegisters(I2C_FLOW_ADDRESS, PX4FLOW_REG, I2C_FRAME_SIZE + I2C_INTEGRAL_FRAME_SIZE, val)){
+      hal.console->printf_P(PSTR("PX4FLOW: Error while reading"));
+      i2c_sem->give();
+      return 0;
+    }
+  }
+
+  if (PX4FLOW_REG == 0x16) {
+    if (hal.i2c->readRegisters(I2C_FLOW_ADDRESS, PX4FLOW_REG, I2C_INTEGRAL_FRAME_SIZE, val)){
+      hal.console->printf_P(PSTR("PX4FLOW: Error while reading"));
+      i2c_sem->give();
+      return 0;
+    }
+  }
+#endif
+
+
+  if (PX4FLOW_REG == 0) {
+    memcpy(&f, val, I2C_FRAME_SIZE);
+    memcpy(&f_integral, &(val[I2C_FRAME_SIZE]), I2C_INTEGRAL_FRAME_SIZE);
+  }
+
+  if (PX4FLOW_REG == 0x16) {
+    memcpy(&f_integral, val, I2C_INTEGRAL_FRAME_SIZE);
+  }
+
+  // report->timestamp = hrt_absolute_time();
+  report->pixel_flow_x_integral = static_cast<float>(f_integral.pixel_flow_x_integral) / 10000.0f;//convert to radians
+  report->pixel_flow_y_integral = static_cast<float>(f_integral.pixel_flow_y_integral) / 10000.0f;//convert to radians
+  report->frame_count_since_last_readout = f_integral.frame_count_since_last_readout;
+  report->ground_distance_m = static_cast<float>(f_integral.ground_distance) / 1000.0f;//convert to meters
+  report->quality = f_integral.qual; //0:bad ; 255 max quality
+  report->gyro_x_rate_integral = static_cast<float>(f_integral.gyro_x_rate_integral) / 10000.0f; //convert to radians
+  report->gyro_y_rate_integral = static_cast<float>(f_integral.gyro_y_rate_integral) / 10000.0f; //convert to radians
+  report->gyro_z_rate_integral = static_cast<float>(f_integral.gyro_z_rate_integral) / 10000.0f; //convert to radians
+  report->integration_timespan = f_integral.integration_timespan; //microseconds
+  report->time_since_last_sonar_update = f_integral.sonar_timestamp;//microseconds
+  report->gyro_temperature = f_integral.gyro_temperature;//Temperature * 100 in centi-degrees Celsius
+
+  report->sensor_id = 0;
+
+  hal.console->printf_P(PSTR("PX4FLOW measurement: ground_distance_m: %f\n"), report->ground_distance_m);
+
+/*
+  // rotate measurements according to parameter
+  float zeroval = 0.0f;
+  rotate_3f(_sensor_rotation, report.pixel_flow_x_integral, report.pixel_flow_y_integral, zeroval); 
+*/
+
+  i2c_sem->give();
+  return 1;
+
+}
+
+// update - read latest values from sensor and fill in x,y and totals.
+void AP_OpticalFlow_Linux::update(void)
+{
+    struct optical_flow_s report;
+    
+    // read the report from the sensor
+    read(&report);
+
+    // process
+    struct OpticalFlow::OpticalFlow_state state;
+    state.device_id = report.sensor_id;
+    state.surface_quality = report.quality;
+    if (report.integration_timespan > 0) {
+        const Vector2f flowScaler = _flowScaler();
+        float flowScaleFactorX = 1.0f + 0.001f * flowScaler.x;
+        float flowScaleFactorY = 1.0f + 0.001f * flowScaler.y;
+        float integralToRate = 1e6f / float(report.integration_timespan);
+        state.flowRate.x = flowScaleFactorX * integralToRate * float(report.pixel_flow_x_integral); // rad/sec measured optically about the X sensor axis
+        state.flowRate.y = flowScaleFactorY * integralToRate * float(report.pixel_flow_y_integral); // rad/sec measured optically about the Y sensor axis
+        state.bodyRate.x = integralToRate * float(report.gyro_x_rate_integral); // rad/sec measured inertially about the X sensor axis
+        state.bodyRate.y = integralToRate * float(report.gyro_y_rate_integral); // rad/sec measured inertially about the Y sensor axis
+    } else {
+        state.flowRate.zero();
+        state.bodyRate.zero();
+    }
+
+#if DEBUG
+    hal.console->printf_P(PSTR("PX4FLOW print: sensor_id: %d\n"), state.device_id);
+    hal.console->printf_P(PSTR("PX4FLOW print: surface_quality: %d\n"), state.surface_quality);
+    hal.console->printf_P(PSTR("PX4FLOW print: flowRate.x: %d\n"), state.flowRate.x);
+    hal.console->printf_P(PSTR("PX4FLOW print: flowRate.y: %d\n"), state.flowRate.y);
+    hal.console->printf_P(PSTR("PX4FLOW print: bodyRate.x: %d\n"), state.bodyRate.x);
+    hal.console->printf_P(PSTR("PX4FLOW print: bodyRate.y: %d\n"), state.bodyRate.y);
+#endif
+    _update_frontend(state);
+}
+
+
+
+#endif // CONFIG_HAL_BOARD == HAL_BOARD_LINUX

libraries/AP_OpticalFlow/AP_OpticalFlow_Linux.h

@@ -0,0 +1,96 @@
+/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+
+#ifndef AP_OpticalFlow_Linux_H
+#define AP_OpticalFlow_Linux_H
+
+#include "OpticalFlow.h"
+
+#include <AP_Math.h>
+
+/* Configuration Constants */
+#define I2C_FLOW_ADDRESS 		0x42	///< 7-bit address. 8-bit address is 0x84, range 0x42 - 0x49
+
+/* PX4FLOW Registers addresses */
+#define PX4FLOW_REG			0x16	///< Measure Register 22
+
+#define PX4FLOW_CONVERSION_INTERVAL	100000	///< in microseconds! 20000 = 50 Hz 100000 = 10Hz
+#define PX4FLOW_I2C_MAX_BUS_SPEED	400000	///< 400 KHz maximum speed
+
+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;
+} 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;
+} i2c_integral_frame;
+
+#define I2C_INTEGRAL_FRAME_SIZE (sizeof(i2c_integral_frame))
+
+/**
+ * Optical flow in NED body frame in SI units.
+ *
+ * @see http://en.wikipedia.org/wiki/International_System_of_Units
+ */
+struct optical_flow_s {
+
+	uint64_t timestamp;		/**< in microseconds since system start  */
+	uint8_t sensor_id;		/**< id of the sensor emitting the flow value */
+	float pixel_flow_x_integral; /**< accumulated optical flow in radians around x axis */
+	float pixel_flow_y_integral; /**< accumulated optical flow in radians around y axis */
+	float gyro_x_rate_integral;	 /**< accumulated gyro value in radians around x axis */
+	float gyro_y_rate_integral;  /**< accumulated gyro value in radians around y axis */
+	float gyro_z_rate_integral;   /**< accumulated gyro value in radians around z axis */
+	float ground_distance_m;	 /**< Altitude / distance to ground in meters */
+	uint32_t integration_timespan; /**<accumulation timespan in microseconds     */
+	uint32_t time_since_last_sonar_update;/**< time since last sonar update in microseconds */
+	uint16_t frame_count_since_last_readout;/**< number of accumulated frames in timespan */
+	int16_t gyro_temperature;/**< 	Temperature * 100 in centi-degrees Celsius */
+	uint8_t	quality;		/**< Average of quality of accumulated frames, 0: bad quality, 255: maximum quality */
+};
+
+class AP_OpticalFlow_Linux : public OpticalFlow_backend
+{
+public:
+    /// constructor
+    AP_OpticalFlow_Linux(OpticalFlow &_frontend);
+
+    // init - initialise the sensor
+    void init();
+
+    // update - read latest values from sensor and fill in x,y and totals.
+    void update(void);    
+
+private:
+	int 	read(optical_flow_s* report);
+    void    print(optical_flow_s* report);    
+	struct 	i2c_frame f;
+	struct 	i2c_integral_frame f_integral;	
+};
+
+#endif

libraries/AP_OpticalFlow/OpticalFlow.cpp

@@ -46,6 +46,8 @@ OpticalFlow::OpticalFlow(void) :
     backend(new AP_OpticalFlow_PX4(*this)),
 #elif CONFIG_HAL_BOARD == HAL_BOARD_SITL
     backend(new AP_OpticalFlow_HIL(*this)),
+#elif CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    backend(new AP_OpticalFlow_Linux(*this)),
 #else
     backend(NULL),
 #endif

libraries/AP_OpticalFlow/OpticalFlow.h

@@ -96,5 +96,6 @@ private:
 #include "OpticalFlow_backend.h"
 #include "AP_OpticalFlow_HIL.h"
 #include "AP_OpticalFlow_PX4.h"
+#include "AP_OpticalFlow_Linux.h"
 
 #endif