为了方便大家深入了解飞控工作原理与编程，ArduPilot 提供了许多示例，位于 /Library 文件中，本文将以串口为例，为大家展示如何利用这些示例进一步深入开发 APM 飞控。
官方文档内容，方便大家对照查阅：https://ardupilot.org/dev/docs/learning-ardupilot-the-example-sketches.html
1，首先进入源码主目录，如何了解目前有哪里示例可以使用呢 ？通过如下指令：
./waf list | grep 'examples'
系统将会列出可以使用的示例，随着版本的更新，示例将会越来越多。
2，我们将以 UART_test 为例，演示整个调试流程， 找到示例源码 UART_test.cpp，位于
/ardupilot/libraries/AP_HAL/examples/UART_test/UART_test.cpp
打开源代码，可以看到内容是重复输出代码编号
void loop(void)
{
test_uart(hal.uartA, "uartA");
test_uart(hal.uartB, "uartB");
test_uart(hal.uartC, "uartC");
test_uart(hal.uartD, "uartD");
test_uart(hal.uartE, "uartE");
// also do a raw printf() on some platforms, which prints to the
// debug console
#if HAL_OS_POSIX_IO
::printf("Hello on debug console at %.3f seconds\n", (double)(AP_HAL::millis() * 0.001f));
#endif
hal.scheduler->delay(1000);
}
3，尝试修改程序，然后编译程序并且下载
3.1，回到源码主目录
3.2，配置硬件，一般不变化不用重新配置，使用指令 ./waf configure --board px4-v2
root@ubuntu:/home/saffron/lrr/ardupilot# ./waf configure --board px4-v2
Setting top to : /home/saffron/lrr/ardupilot
Setting out to : /home/saffron/lrr/ardupilot/build
Autoconfiguration : enabled
Setting board to : px4-v2
Checking for program 'arm-none-eabi-ar' : /opt/gcc-arm-none-eabi-6-2017-q2-update/bin/arm-none-eabi-ar
Using toolchain : arm-none-eabi
Checking for 'g++' (C++ compiler) : /usr/lib/ccache/arm-none-eabi-g++
Checking for 'gcc' (C compiler) : /usr/lib/ccache/arm-none-eabi-gcc
Checking for c flags '-MMD' : yes
Checking for cxx flags '-MMD' : yes
Checking for HAVE_CMATH_ISFINITE : no
Checking for HAVE_CMATH_ISINF : no
Checking for HAVE_CMATH_ISNAN : no
Checking for NEED_CMATH_ISFINITE_STD_NAMESPACE : no
Checking for NEED_CMATH_ISINF_STD_NAMESPACE : no
Checking for NEED_CMATH_ISNAN_STD_NAMESPACE : no
Checking for header endian.h : not found
Checking for header byteswap.h : not found
Checking for program 'cmake' : /usr/bin/cmake
Checking cmake version : 3.10.2
Checking for program 'ninja, ninja-build' : not found
Checking for program 'make' : /usr/bin/make
Checking for program 'python' : /usr/bin/python
Checking for python version >= 2.7.0 : 2.7.17
Checking for program 'python' : /usr/bin/python
Checking for python version >= 2.7.0 : 2.7.17
Source is git repository : yes
Update submodules : yes
Checking for program 'git' : /usr/bin/git
Gtest : STM32 boards currently don't support compiling gtest
Checking for program 'arm-none-eabi-size' : /opt/gcc-arm-none-eabi-6-2017-q2-update/bin/arm-none-eabi-size
Benchmarks : disabled
Unit tests : disabled
Checking for program 'rsync' : /usr/bin/rsync
'configure' finished successfully (1.258s)
3.3，编译与下载指定代码，指令 ./waf build --target examples/UART_test --upload
root@ubuntu:/home/saffron/lrr/ardupilot# ./waf build --target examples/UART_test --upload
Waf: Entering directory `/home/saffron/lrr/ardupilot/build/px4-v2'
[ 8/15] CMake Configure px4
-- nuttx-px4fmu-v2-apm
-- could not find gdbtui
-- could not find ddd
-- could not find gdbtui
-- could not find ddd
-- The ASM compiler identification is GNU
-- Found assembler: /usr/lib/ccache/arm-none-eabi-gcc
-- Found PythonInterp: /usr/bin/python (found version "2.7.17")
-- GIT_DESC = 1e7ed30b1710b55f8a7509800187d51e63bb2143
-- Configuring done
-- Generating done
-- Build files have been written to: /home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware
INCLUDE_DIRS=/home/saffron/lrr/ardupilot/modules/PX4Firmware/src;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/src;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/modules;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/include;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/lib;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/platforms;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/drivers/boards/px4fmu-v2;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/src/modules/px4_messages;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/src/modules;/home/saffron/lrr/ardupilot/modules/PX4Firmware/mavlink/include/mavlink;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/lib/DriverFramework/framework/include;src/lib/matrix;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/include;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/include/cxx;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/arch/chip;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/arch/common
ADDING DRIVERS
[14/15] CMake Build px4 msg_gen
Scanning dependencies of target git_genmsg
[ 0%] Built target git_genmsg
Scanning dependencies of target git_gencpp
[ 33%] Built target git_gencpp
Scanning dependencies of target msg_gen
[100%] Built target msg_gen
[15/15] CMake Build px4 prebuild_targets
Scanning dependencies of target __nuttx_patch_px4fmu-v2
[ 0%] Built target __nuttx_patch_px4fmu-v2
Scanning dependencies of target __nuttx_copy_px4fmu-v2
[ 0%] Built target __nuttx_copy_px4fmu-v2
Scanning dependencies of target nuttx_export_px4fmu-v2
[100%] Built target nuttx_export_px4fmu-v2
Scanning dependencies of target prebuild_targets
[100%] Built target prebuild_targets
[470/479] Compiling libraries/AP_HAL/examples/UART_test/UART_test.cpp
[471/479] CMake Configure px4
-- nuttx-px4fmu-v2-apm
-- could not find gdbtui
-- could not find ddd
-- could not find gdbtui
-- could not find ddd
-- The ASM compiler identification is GNU
-- Found assembler: /usr/lib/ccache/arm-none-eabi-gcc
-- Found PythonInterp: /usr/bin/python (found version "2.7.17")
-- GIT_DESC = 1e7ed30b1710b55f8a7509800187d51e63bb2143
-- Configuring done
-- Generating done
[472/479] Linking build/px4-v2/lib/examples/libUART_test.a
-- Build files have been written to: /home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware
INCLUDE_DIRS=/home/saffron/lrr/ardupilot/modules/PX4Firmware/src;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/src;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/modules;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/include;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/lib;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/platforms;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/drivers/boards/px4fmu-v2;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/src/modules/px4_messages;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/src/modules;/home/saffron/lrr/ardupilot/modules/PX4Firmware/mavlink/include/mavlink;/home/saffron/lrr/ardupilot/modules/PX4Firmware/src/lib/DriverFramework/framework/include;src/lib/matrix;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/include;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/include/cxx;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/arch/chip;/home/saffron/lrr/ardupilot/build/px4-v2/modules/PX4Firmware/px4fmu-v2/NuttX/nuttx-export/arch/common
ADDING DRIVERS
[473/479] CMake Build px4 fw_io
Loaded firmware for 9,0, size: 289632 bytes, waiting for the bootloader...
If the board does not respond within 1-2 seconds, unplug and re-plug the USB connector.
Found board 9,0 bootloader rev 4 on /dev/serial/by-id/usb-3D_Robotics_PX4_BL_FMU_v2.x_0-if00
50583400 00ac2600 00100000 00ffffff ffffffff ffffffff ffffffff ffffffff 66ed47ff ff73cc15 c8ad940c dbc59f39 d6c20e06 f953d3ef f3073019 d035ab0d 3f60334e 10dda9f8 cdb0cbbd 42cdc6b6 3ba305f7 81532581 84ee3da6 23bc6340 8321be68 edd356c9 1e3b8f5c 5e07decc 9c6be5a2 458a1513 4bbbbc21 eda35ce5 a8b840a5 ef019ca5 c89bb183 bb00f0c0 06db1a26 7375ff57 1ca41d94 24aa662e ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff type: PX4
idtype: =00
vid: 000026ac
pid: 00000010
coa: Zu1H//9zzBXIrZQM28WfOdbCDgb5U9Pv8wcwGdA1qw0/YDNOEN2p+M2wy71Czca2O6MF94FTJYGE7j2mI7xjQIMhvmjt01bJHjuPXF4H3syca+WiRYoVE0u7vCHto1zlqLhApe8BnKXIm7GDuwDwwAbbGiZzdf9XHKQdlCSqZi4=
sn: 0038001f3432470d31323533
Erase : [====================] 100.0%
Program: [====================] 100.0%
Verify : [====================] 100.0%
Rebooting.
[100%] Built target upload
Attempting reboot on /dev/serial/by-id/usb-3D_Robotics_PX4_FMU_v2.x_0-if00 with baudrate=57600...
If the board does not respond, unplug and re-plug the USB connector.
Waf: Leaving directory `/home/saffron/lrr/ardupilot/build/px4-v2'
BUILD SUMMARY
Build directory: /home/saffron/lrr/ardupilot/build/px4-v2
Target Text Data BSS Total
-----------------------------------------------
examples/UART_test 286872 2760 39356 328988
PX4
The ELF files are pointed by the path in the "Target" column. The .px4 files are in
the same directory of their corresponding ELF files.
PX4IO
Binary Text Data BSS Total
-----------------------------------------------
px4-extra-files/px4io 39604 600 3134 43338
Build commands will be stored in build/px4-v2/compile_commands.json
'build' finished successfully (35.825s)
4，下载成功后，查看代码运行结果，通过串口调试助手查看
可以看出调试代码已经可以正常运行了。
本文章通过串口调试示例，引导大家深入学习 APM 编程。