标签：使用 his neither 发布者 poll 清理 位置 开机 mission
本文主要内容翻译自官方文档：https://dev.px4.io/en/middleware/uorb.html
在前一篇笔记中使用uORB完成消息传递，实现了一个简单示例程序，本文将对uORB进行系统学习。
uORB是一种异步发布(publish)/订阅(subscribe)机制的消息API，该机制用于在线程/进程之间通信。uORB在其他程序启动之前自动启动，因为其他很多程序依赖于他。
使用uorb start命令启动它，可以使用uorb_tests开始单元测试。
# This is similar to the mavlink message ATTITUDE_QUATERNION, but for onboard use float32 rollspeed # Angular velocity about body north axis (x) in rad/s float32 pitchspeed # Angular velocity about body east axis (y) in rad/s float32 yawspeed # Angular velocity about body down axis (z) in rad/s float32[4] q # Quaternion (NED) # TOPICS vehicle_attitude vehicle_attitude_groundtruth vehicle_vision_attitude
在编译后，将在编译目录的src/modules/uORB/topics文件夹下生成vehicle_attitude.h头文件，内容如下：
/**************************************************************************** * * Copyright (C) 2013-2016 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name PX4 nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /* Auto-generated by genmsg_cpp from file /home/spy/src/Firmware/msg/vehicle_attitude.msg */ #pragma once #include <stdint.h> #ifdef __cplusplus #include <cstring> #else #include <string.h> #endif #include <uORB/uORB.h> #ifndef __cplusplus #endif #ifdef __cplusplus struct __EXPORT vehicle_attitude_s { #else struct vehicle_attitude_s { #endif uint64_t timestamp; // required for logger float roll; float pitch; float yaw; float q[4]; uint8_t _padding0[4]; // required for logger #ifdef __cplusplus #endif }; /* register this as object request broker structure */ ORB_DECLARE(vehicle_attitude); ORB_DECLARE(vehicle_attitude_groundtruth); ORB_DECLARE(vehicle_vision_attitude);
对于生成的每个C/C++结构体，将会自动添加一个uint64_t timestamp成员，该成员用于logger模块记录数据，所以确保在发布消息时给该成员赋值。
为了在代码里使用该主题，需要包含如下头文件：
#include <uORB/topics/topic_name.h>
在.msg的代码中加入如下行，则一条msg定义可以被多个独立的主题实例所使用：
# TOPICS mission offboard_mission onboard_mission
之后可以在代码中使用 ORB_ID(offboard_mission)来获取主题ID。
ls /obj
笔者在飞控刚开机时使用qgroundcontrol的MAVLink控制台，得到所有主题列表如下图：
nsh> ls /obj /obj: _obj_ actuator_armed0 actuator_controls_00 actuator_controls_10 actuator_controls_20 actuator_controls_30 actuator_outputs0 actuator_outputs1 adc_report0 airspeed0 att_pos_mocap0 battery_status0 camera_capture0 camera_trigger0 commander_state0 control_state0 cpuload0 differential_pressure0 distance_sensor0 ekf2_innovations0 ekf2_timestamps0 esc_status0 estimator_status0 fw_pos_ctrl_status0 geofence_result0 gps_dump0 gps_inject_data0 home_position0 input_rc0 led_control0 log_message0 manual_control_setpoint0 mavlink_log0 mc_att_ctrl_status0 mission_result0 multirotor_motor_limits0 multirotor_motor_limits1 offboard_control_mode0 offboard_mission0 onboard_mission0 optical_flow0 parameter_update0 position_setpoint_triplet0 power_button_state0 rc_channels0 rc_parameter_map0 safety0 satellite_info0 sensor_accel0 sensor_accel1 sensor_accel2 sensor_baro0 sensor_baro1 sensor_combined0 sensor_correction0 sensor_gyro0 sensor_gyro1 sensor_gyro2 sensor_mag0 sensor_mag1 sensor_mag2 sensor_mag3 sensor_preflight0 sensor_selection0 servorail_status0 subsystem_info0 system_power0 task_stack_info0 tecs_status0 telemetry_status0 uavcan_parameter_request0 uavcan_parameter_value0 vehicle_attitude0 vehicle_attitude_setpoint0 vehicle_command0 vehicle_command_ack0 vehicle_control_mode0 vehicle_global_position0 vehicle_gps_position0 vehicle_land_detected0 vehicle_local_position0 vehicle_local_position_setpoint0 vehicle_rates_setpoint0 vehicle_status0 vehicle_status_flags0 vehicle_vision_attitude0 vehicle_vision_position0 vtol_vehicle_status0 wind_estimate0
使用 listener 可以监听主题：
listener sensor_accel 5
文档中给出listener只能在Pixracer中使用，不过笔者使用pixhawk2.1运行pixhawk固件，也可以运行listener命令
结果如下：
nsh> listener sensor_accel 5 TOPIC: sensor_accel instance 0 #1 timestamp: 45504766 integral_dt: 4000 error_count: 0 x: 0.0126 y: 0.4502 z: -9.7865 x_integral: 0.0001 y_integral: 0.0018 z_integral: -0.0392 temperature: 44.7562 range_m_s2: 156.9064 scaling: 0.0048 x_raw: 41 y_raw: -123 z_raw: -2067 temperature_raw: 3522 device_id: 1442082 TOPIC: sensor_accel instance 0 #2 timestamp: 45564766 integral_dt: 3991 error_count: 0 x: 0.0208 y: 0.4487 z: -9.7956 x_integral: 0.0001 y_integral: 0.0018 z_integral: -0.0390 temperature: 44.7424 range_m_s2: 156.9064 scaling: 0.0048 x_raw: 45 y_raw: -121 z_raw: -2067 temperature_raw: 3517 device_id: 1442082 TOPIC: sensor_accel instance 0 #3 timestamp: 45620766 integral_dt: 4000 error_count: 0 x: 0.0133 y: 0.4447 z: -9.7794 x_integral: 0.0000 y_integral: 0.0018 z_integral: -0.0391 temperature: 44.7368 range_m_s2: 156.9064 scaling: 0.0048 x_raw: 44 y_raw: -122 z_raw: -2064 temperature_raw: 3515 device_id: 1442082 TOPIC: sensor_accel instance 0 #4 timestamp: 45670381 integral_dt: 4013 error_count: 0 x: 0.0179 y: 0.4408 z: -9.7816 x_integral: 0.0000 y_integral: 0.0017 z_integral: -0.0393 temperature: 44.7673 range_m_s2: 156.9064 scaling: 0.0048 x_raw: 47 y_raw: -121 z_raw: -2065 temperature_raw: 3526 device_id: 1442082 TOPIC: sensor_accel instance 0 #5 timestamp: 45730379 integral_dt: 4000 error_count: 0 x: 0.0164 y: 0.4363 z: -9.7636 x_integral: 0.0000 y_integral: 0.0018 z_integral: -0.0390 temperature: 44.7645 range_m_s2: 156.9064 scaling: 0.0048 x_raw: 49 y_raw: -123 z_raw: -2062 temperature_raw: 3525 device_id: 1442082
nsh> uorb top update: 1s, num topics: 86 TOPIC NAME INST #SUB #MSG #LOST #QSIZE sensor_baro 0 2 66 22 1 sensor_baro 1 1 67 0 1 sensor_mag 0 1 42 0 1 vehicle_gps_position 0 6 4 11 1 sensor_mag 1 1 108 8 1 sensor_accel 0 1 248 0 1 sensor_gyro 0 2 248 0 1 sensor_gyro 1 2 238 7 1 sensor_mag 2 1 99 0 1 sensor_accel 1 1 223 0 1 sensor_mag 3 1 97 2 1 sensor_accel 2 1 250 2 1 sensor_gyro 2 2 250 2 1 adc_report 0 1 99 0 1 system_power 0 2 99 16 1 vehicle_control_mode 0 7 4 0 1 actuator_controls_0 0 7 248 1022 1 sensor_combined 0 6 248 927 1 sensor_preflight 0 1 248 0 1 battery_status 0 6 82 218 1 vehicle_status 0 8 4 4 1 actuator_armed 0 7 4 2 1 safety 0 1 41 0 1 vehicle_local_position 0 7 248 712 1 vehicle_attitude 0 5 248 836 1 vehicle_status_flags 0 0 83 0 1
上文中的内容主要是官方文档里的，给出了uORB的概述，但是没有给出关键函数的解析，由于这部分比较重要，下一篇中笔者将结合代码和文档给出uORB流程和其中关键函数的解析。
标签：使用 his neither 发布者 poll 清理 位置 开机 mission
原文地址：http://www.cnblogs.com/spyplus/p/7401555.html
