mirror of
https://gitee.com/mirrors_PX4/PX4-Autopilot.git
synced 2026-04-14 10:07:39 +08:00
556 lines
21 KiB
Markdown
556 lines
21 KiB
Markdown
# 搭建你的第一个应用（Hello Shy）
|
||
|
||
本文主要说明如何创建并运行你的第一个板载应用程序。
|
||
它涵盖了 PX4 应用程序开发所需的所有基本概念和 API。
|
||
|
||
:::info
|
||
For simplicity, more advanced features like start/stop functionality and command-line arguments are omitted.
|
||
These are covered in [Application/Module Template](../modules/module_template.md).
|
||
:::
|
||
|
||
## 系统必备组件
|
||
|
||
以下内容是您需要提前准备的：
|
||
|
||
- [PX4 SITL Simulator](../simulation/index.md) _or_ a [PX4-compatible flight controller](../flight_controller/index.md).
|
||
- [PX4 Development Toolchain](../dev_setup/dev_env.md) for the desired target.
|
||
- [Download the PX4 Source Code](../dev_setup/building_px4.md#download-the-px4-source-code) from Github
|
||
|
||
The source code [PX4-Autopilot/src/examples/px4_simple_app](https://github.com/PX4/PX4-Autopilot/tree/main/src/examples/px4_simple_app) directory contains a completed version of this tutorial that you can review if you get stuck.
|
||
|
||
- Rename (or delete) the **px4_simple_app** directory.
|
||
|
||
## 最小的应用程序
|
||
|
||
In this section we create a _minimal application_ that just prints out `Hello Sky!`.
|
||
This consists of a single _C_ file and a _cmake_ definition (which tells the toolchain how to build the application).
|
||
|
||
1. Create a new directory **PX4-Autopilot/src/examples/px4_simple_app**.
|
||
|
||
2. Create a new C file in that directory named **px4_simple_app.c**:
|
||
- Copy in the default header to the top of the page.
|
||
该注释应出现在所有贡献的文件中！
|
||
|
||
```c
|
||
/****************************************************************************
|
||
*
|
||
* Copyright (c) 2012-2022 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.
|
||
*
|
||
****************************************************************************/
|
||
```
|
||
|
||
- 将下面的代码复制到头部注释的下方，
|
||
该注释应出现在所有贡献的文件中！
|
||
|
||
```c
|
||
/**
|
||
* @file px4_simple_app.c
|
||
* Minimal application example for PX4 autopilot
|
||
*
|
||
* @author Example User <mail@example.com>
|
||
*/
|
||
|
||
#include <px4_platform_common/log.h>
|
||
|
||
__EXPORT int px4_simple_app_main(int argc, char *argv[]);
|
||
|
||
int px4_simple_app_main(int argc, char *argv[])
|
||
{
|
||
PX4_INFO("Hello Sky!");
|
||
return OK;
|
||
}
|
||
```
|
||
|
||
:::tip
|
||
|
||
The main function must be named `<module_name>_main` and exported from the module as shown.
|
||
|
||
|
||
:::
|
||
|
||
:::tip
|
||
|
||
`PX4_INFO` is the equivalent of `printf` for the PX4 shell (included from **px4_platform_common/log.h**).
|
||
There are different log levels: `PX4_INFO`, `PX4_WARN`, `PX4_ERR`, `PX4_DEBUG`.
|
||
Warnings and errors are additionally added to the [ULog](../dev_log/ulog_file_format.md) and shown on [Flight Review](https://logs.px4.io/).
|
||
|
||
|
||
:::
|
||
|
||
3. Create and open a new _cmake_ definition file named **CMakeLists.txt**.
|
||
复制下面的文本：
|
||
|
||
```cmake
|
||
############################################################################
|
||
#
|
||
# Copyright (c) 2015 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.
|
||
#
|
||
############################################################################
|
||
px4_add_module(
|
||
MODULE examples__px4_simple_app
|
||
MAIN px4_simple_app
|
||
STACK_MAIN 2000
|
||
SRCS
|
||
px4_simple_app.c
|
||
DEPENDS
|
||
)
|
||
```
|
||
|
||
The `px4_add_module()` method builds a static library from a module description.
|
||
|
||
- The `MODULE` block is the Firmware-unique name of the module (by convention the module name is prefixed by parent directories back to `src`).
|
||
- The `MAIN` block lists the entry point of the module, which registers the command with NuttX so that it can be called from the PX4 shell or SITL console.
|
||
|
||
:::tip
|
||
The `px4_add_module()` format is documented in [PX4-Autopilot/cmake/px4_add_module.cmake](https://github.com/PX4/PX4-Autopilot/blob/main/cmake/px4_add_module.cmake). <!-- NEED px4_version -->
|
||
|
||
:::
|
||
|
||
::: info
|
||
If you specify `DYNAMIC` as an option to `px4_add_module`, a _shared library_ is created instead of a static library on POSIX platforms (these can be loaded without having to recompile PX4, and shared to others as binaries rather than source code).
|
||
Your app will not become a builtin command, but ends up in a separate file called `examples__px4_simple_app.px4mod`.
|
||
You can then run your command by loading the file at runtime using the `dyn` command: `dyn ./examples__px4_simple_app.px4mod`
|
||
|
||
:::
|
||
|
||
4. Create and open a new _Kconfig_ definition file named **Kconfig** and define your symbol for naming (see [Kconfig naming convention](../hardware/porting_guide_config.md#px4-kconfig-symbol-naming-convention)).
|
||
复制下面的文本：
|
||
|
||
```text
|
||
menuconfig EXAMPLES_PX4_SIMPLE_APP
|
||
bool "px4_simple_app"
|
||
default n
|
||
---help---
|
||
Enable support for px4_simple_app
|
||
```
|
||
|
||
## 编译应用程序/固件
|
||
|
||
应用程序的编写至此完成。
|
||
为了运行它，您首先需要确保它是作为 PX4 的一部分构建的。
|
||
Applications are added to the build/firmware in the appropriate board-level _px4board_ file for your target:
|
||
|
||
- PX4 SITL (Simulator): [PX4-Autopilot/boards/px4/sitl/default.px4board](https://github.com/PX4/PX4-Autopilot/blob/main/boards/px4/sitl/default.px4board)
|
||
- Pixhawk v1/2: [PX4-Autopilot/boards/px4/fmu-v2/default.px4board](https://github.com/PX4/PX4-Autopilot/blob/main/boards/px4/fmu-v2/default.px4board)
|
||
- Pixracer (px4/fmu-v4): [PX4-Autopilot/boards/px4/fmu-v4/default.px4board](https://github.com/PX4/PX4-Autopilot/blob/main/boards/px4/fmu-v4/default.px4board)
|
||
- _px4board_ files for other boards can be found in [PX4-Autopilot/boards/](https://github.com/PX4/PX4-Autopilot/tree/main/boards)
|
||
|
||
To enable the compilation of the application into the firmware add the corresponding Kconfig key `CONFIG_EXAMPLES_PX4_SIMPLE_APP=y` in the _px4board_ file or run [boardconfig](../hardware/porting_guide_config.md#px4-menuconfig-setup) `make px4_fmu-v4_default boardconfig`:
|
||
|
||
```
|
||
examples --->
|
||
[x] PX4 Simple app ----
|
||
```
|
||
|
||
:::info
|
||
The line will already be present for most files, because the examples are included in firmware by default.
|
||
:::
|
||
|
||
使用特定板的命令构建示例：
|
||
|
||
- jMAVSim Simulator: `make px4_sitl_default jmavsim`
|
||
- Pixhawk v1/2: `make px4_fmu-v2_default` (or just `make px4_fmu-v2`)
|
||
- Pixhawk v3: `make px4_fmu-v4_default`
|
||
- Other boards: [Building the Code](../dev_setup/building_px4.md#building-for-nuttx)
|
||
|
||
## 测试应用（硬件）
|
||
|
||
### 将固件上传至飞控板
|
||
|
||
启用上传器，然后重启飞控板：
|
||
|
||
- Pixhawk v1/2: `make px4_fmu-v2_default upload`
|
||
- Pixhawk v3: `make px4_fmu-v4_default upload`
|
||
|
||
在您重启飞控板之前，它应该打印一些编译消息，并在最后打印：
|
||
|
||
```sh
|
||
Loaded firmware for X,X, waiting for the bootloader...
|
||
```
|
||
|
||
一旦飞控板被重启并完成了固件的上传，命令行界面将输出：
|
||
|
||
```sh
|
||
Erase : [====================] 100.0%
|
||
Program: [====================] 100.0%
|
||
Verify : [====================] 100.0%
|
||
Rebooting.
|
||
|
||
[100%] Built target upload
|
||
```
|
||
|
||
### 连接至控制台
|
||
|
||
Now connect to the [system console](../debug/system_console.md) either via serial or USB.
|
||
Hitting **ENTER** will bring up the shell prompt:
|
||
|
||
```sh
|
||
nsh>
|
||
```
|
||
|
||
输入“help”并按回车键
|
||
|
||
```sh
|
||
nsh> help
|
||
help usage: help [-v] [<cmd>]
|
||
|
||
[ df kill mkfifo ps sleep
|
||
? echo losetup mkrd pwd test
|
||
cat exec ls mh rm umount
|
||
cd exit mb mount rmdir unset
|
||
cp free mkdir mv set usleep
|
||
dd help mkfatfs mw sh xd
|
||
|
||
Builtin Apps:
|
||
reboot
|
||
perf
|
||
top
|
||
..
|
||
px4_simple_app
|
||
..
|
||
sercon
|
||
serdis
|
||
```
|
||
|
||
Note that `px4_simple_app` is now part of the available commands.
|
||
Start it by typing `px4_simple_app` and ENTER:
|
||
|
||
```sh
|
||
nsh> px4_simple_app
|
||
Hello Sky!
|
||
```
|
||
|
||
该应用程序现在已正确注册到系统中，并且可以扩展以实际执行实用的任务。
|
||
|
||
## 测试应用（SITL）
|
||
|
||
If you're using SITL the _PX4 console_ is automatically started (see [Building the Code > First Build (Using a Simulator)](../dev_setup/building_px4.md#first-build-using-a-simulator)).
|
||
As with the _nsh console_ (see previous section) you can type `help` to see the list of built-in apps.
|
||
|
||
Enter `px4_simple_app` to run the minimal app.
|
||
|
||
```sh
|
||
pxh> px4_simple_app
|
||
INFO [px4_simple_app] Hello Sky!
|
||
```
|
||
|
||
现在可以扩展该应用程序以实际执行实用的任务
|
||
|
||
## 订阅传感器数据
|
||
|
||
为了做一些实用的事情，应用程序需要订阅输入和发布输出（例如电机或伺服命令）。
|
||
|
||
:::tip
|
||
The benefits of the PX4 hardware abstraction comes into play here!
|
||
无需以任何方式与传感器驱动程序交互，如果板或传感器更新，也无需更新您的应用程序。
|
||
:::
|
||
|
||
Individual message channels between applications are called [topics](../middleware/uorb.md). For this tutorial, we are interested in the [SensorCombined](https://github.com/PX4/PX4-Autopilot/blob/main/msg/SensorCombined.msg) topic, which holds the synchronized sensor data of the complete system.
|
||
|
||
订阅主题很简单：
|
||
|
||
```cpp
|
||
#include <uORB/topics/sensor_combined.h>
|
||
..
|
||
int sensor_sub_fd = orb_subscribe(ORB_ID(sensor_combined));
|
||
```
|
||
|
||
The `sensor_sub_fd` is a topic handle and can be used to very efficiently perform a blocking wait for new data.
|
||
当前线程进入休眠状态，一旦有新数据可用就会被调度器自动唤醒，等待时不消耗任何 CPU 周期。
|
||
To do this, we use the [poll()](https://pubs.opengroup.org/onlinepubs/007908799/xsh/poll.html) POSIX system call.
|
||
|
||
Adding `poll()` to the subscription looks like (_pseudocode, look for the full implementation below_):
|
||
|
||
```cpp
|
||
#include <poll.h>
|
||
#include <uORB/topics/sensor_combined.h>
|
||
..
|
||
int sensor_sub_fd = orb_subscribe(ORB_ID(sensor_combined));
|
||
|
||
/* one could wait for multiple topics with this technique, just using one here */
|
||
px4_pollfd_struct_t fds[] = {
|
||
{ .fd = sensor_sub_fd, .events = POLLIN },
|
||
};
|
||
|
||
while (true) {
|
||
/* wait for sensor update of 1 file descriptor for 1000 ms (1 second) */
|
||
int poll_ret = px4_poll(fds, 1, 1000);
|
||
..
|
||
if (fds[0].revents & POLLIN) {
|
||
/* obtained data for the first file descriptor */
|
||
struct sensor_combined_s raw;
|
||
/* copy sensors raw data into local buffer */
|
||
orb_copy(ORB_ID(sensor_combined), sensor_sub_fd, &raw);
|
||
PX4_INFO("Accelerometer:\t%8.4f\t%8.4f\t%8.4f",
|
||
(double)raw.accelerometer_m_s2[0],
|
||
(double)raw.accelerometer_m_s2[1],
|
||
(double)raw.accelerometer_m_s2[2]);
|
||
}
|
||
}
|
||
```
|
||
|
||
再次编译应用程序可以输入：
|
||
|
||
```sh
|
||
make
|
||
```
|
||
|
||
### 测试 uORB 消息订阅
|
||
|
||
最后一步是通过在 nsh shell 中键入以下内容来启动您的应用程序作为后台进程/任务：
|
||
|
||
```sh
|
||
px4_simple_app &
|
||
```
|
||
|
||
您的应用程序将在控制台中显示 5 个传感器值（译者注：需要使用后面的完整示例中的代码，如果使用上面的伪代码会连续输出并无法退出），然后退出：
|
||
|
||
```sh
|
||
[px4_simple_app] Accelerometer: 0.0483 0.0821 0.0332
|
||
[px4_simple_app] Accelerometer: 0.0486 0.0820 0.0336
|
||
[px4_simple_app] Accelerometer: 0.0487 0.0819 0.0327
|
||
[px4_simple_app] Accelerometer: 0.0482 0.0818 0.0323
|
||
[px4_simple_app] Accelerometer: 0.0482 0.0827 0.0331
|
||
[px4_simple_app] Accelerometer: 0.0489 0.0804 0.0328
|
||
```
|
||
|
||
:::tip
|
||
The [Module Template for Full Applications](../modules/module_template.md) can be used to write background process that can be controlled from the command line.
|
||
:::
|
||
|
||
## 发布数据
|
||
|
||
To use the calculated outputs, the next step is to _publish_ the results.
|
||
下面我们将展示如何发布姿态主题。
|
||
|
||
:::info
|
||
We've chosen `attitude` because we know that the _mavlink_ app forwards it to the ground control station - providing an easy way to look at the results.
|
||
:::
|
||
|
||
The interface is pretty simple: initialize the `struct` of the topic to be published and advertise the topic:
|
||
|
||
```c
|
||
#include <uORB/topics/vehicle_attitude.h>
|
||
..
|
||
/* advertise attitude topic */
|
||
struct vehicle_attitude_s att;
|
||
memset(&att, 0, sizeof(att));
|
||
orb_advert_t att_pub_fd = orb_advertise(ORB_ID(vehicle_attitude), &att);
|
||
```
|
||
|
||
在主循环中，随时发布信息：
|
||
|
||
```c
|
||
orb_publish(ORB_ID(vehicle_attitude), att_pub_fd, &att);
|
||
```
|
||
|
||
## 完整的示例代码
|
||
|
||
The [complete example code](https://github.com/PX4/PX4-Autopilot/blob/main/src/examples/px4_simple_app/px4_simple_app.c) is now:
|
||
|
||
```c
|
||
/****************************************************************************
|
||
*
|
||
* Copyright (c) 2012-2019 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.
|
||
*
|
||
****************************************************************************/
|
||
|
||
/**
|
||
* @file px4_simple_app.c
|
||
* Minimal application example for PX4 autopilot
|
||
*
|
||
* @author Example User <mail@example.com>
|
||
*/
|
||
|
||
#include <px4_platform_common/px4_config.h>
|
||
#include <px4_platform_common/log.h>
|
||
#include <px4_platform_common/tasks.h>
|
||
#include <px4_platform_common/posix.h>
|
||
#include <unistd.h>
|
||
#include <stdio.h>
|
||
#include <poll.h>
|
||
#include <string.h>
|
||
#include <math.h>
|
||
|
||
#include <uORB/uORB.h>
|
||
#include <uORB/topics/sensor_combined.h>
|
||
#include <uORB/topics/vehicle_attitude.h>
|
||
|
||
__EXPORT int px4_simple_app_main(int argc, char *argv[]);
|
||
|
||
int px4_simple_app_main(int argc, char *argv[])
|
||
{
|
||
PX4_INFO("Hello Sky!");
|
||
|
||
/* subscribe to sensor_combined topic */
|
||
int sensor_sub_fd = orb_subscribe(ORB_ID(sensor_combined));
|
||
/* limit the update rate to 5 Hz */
|
||
orb_set_interval(sensor_sub_fd, 200);
|
||
|
||
/* advertise attitude topic */
|
||
struct vehicle_attitude_s att;
|
||
memset(&att, 0, sizeof(att));
|
||
orb_advert_t att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);
|
||
|
||
/* one could wait for multiple topics with this technique, just using one here */
|
||
px4_pollfd_struct_t fds[] = {
|
||
{ .fd = sensor_sub_fd, .events = POLLIN },
|
||
/* there could be more file descriptors here, in the form like:
|
||
* { .fd = other_sub_fd, .events = POLLIN },
|
||
*/
|
||
};
|
||
|
||
int error_counter = 0;
|
||
|
||
for (int i = 0; i < 5; i++) {
|
||
/* wait for sensor update of 1 file descriptor for 1000 ms (1 second) */
|
||
int poll_ret = px4_poll(fds, 1, 1000);
|
||
|
||
/* handle the poll result */
|
||
if (poll_ret == 0) {
|
||
/* this means none of our providers is giving us data */
|
||
PX4_ERR("Got no data within a second");
|
||
|
||
} else if (poll_ret < 0) {
|
||
/* this is seriously bad - should be an emergency */
|
||
if (error_counter < 10 || error_counter % 50 == 0) {
|
||
/* use a counter to prevent flooding (and slowing us down) */
|
||
PX4_ERR("ERROR return value from poll(): %d", poll_ret);
|
||
}
|
||
|
||
error_counter++;
|
||
|
||
} else {
|
||
|
||
if (fds[0].revents & POLLIN) {
|
||
/* obtained data for the first file descriptor */
|
||
struct sensor_combined_s raw;
|
||
/* copy sensors raw data into local buffer */
|
||
orb_copy(ORB_ID(sensor_combined), sensor_sub_fd, &raw);
|
||
PX4_INFO("Accelerometer:\t%8.4f\t%8.4f\t%8.4f",
|
||
(double)raw.accelerometer_m_s2[0],
|
||
(double)raw.accelerometer_m_s2[1],
|
||
(double)raw.accelerometer_m_s2[2]);
|
||
|
||
/* set att and publish this information for other apps
|
||
the following does not have any meaning, it's just an example
|
||
*/
|
||
att.q[0] = raw.accelerometer_m_s2[0];
|
||
att.q[1] = raw.accelerometer_m_s2[1];
|
||
att.q[2] = raw.accelerometer_m_s2[2];
|
||
|
||
orb_publish(ORB_ID(vehicle_attitude), att_pub, &att);
|
||
}
|
||
|
||
/* there could be more file descriptors here, in the form like:
|
||
* if (fds[1..n].revents & POLLIN) {}
|
||
*/
|
||
}
|
||
}
|
||
|
||
PX4_INFO("exiting");
|
||
|
||
return 0;
|
||
}
|
||
```
|
||
|
||
## 运行完整的示例
|
||
|
||
最后运行你的应用程序：
|
||
|
||
```sh
|
||
px4_simple_app
|
||
```
|
||
|
||
If you start _QGroundControl_, you can check the sensor values in the real time plot ([Analyze > MAVLink Inspector](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/analyze_view/mavlink_inspector.html)).
|
||
|
||
## 总结
|
||
|
||
本教程涵盖了所有开发基本 PX4 自动驾驶仪应用程序的内容。
|
||
Keep in mind that the full list of uORB messages/topics is [available here](https://github.com/PX4/PX4-Autopilot/tree/main/msg/) and that the headers are well documented and serve as reference.
|
||
|
||
Further information and troubleshooting/common pitfalls can be found here: [uORB](../middleware/uorb.md).
|
||
|
||
下一页提供了一个模板，用于编写具有启动和停止功能的完整应用程序。
|