PX4学习之-uORB简单体验
一、前言
最近项目使用到 CPU2 与 CPU0 之间的通信, 使用定时器传递消息到 CPU0 后, CPU0 需要将消息分发到不同的应用程序里面. PX4 里面使用的是 uORB 多线程/进程通信机制.
uORB 相关介绍参考: 官方 uORB 介绍 以及 无人机中级篇：第三讲：uORB原理与使用, 下文中的代码细节也不做过多解释。
目前使用的是 Firmware 的 1.82 版本 . 下文使用到的文件夹地址如下:
-
uORB 库文件位于
Firmware/src/modules/uORB. -
configs 文件位于
Firmware/cmake/configs -
drivers 文件位于
Firmware/src/drivers -
msg 文件位于
Firmware/msg
二、Coding
主要的步骤为:
- 新建 msg
- 新建 publish 和 subscriber
- 将publish 和 subscriber 添加到 configs 目录下对应的板子里面去
- 编译上传。
2.1 新建 msg
在 msg 目录下面新建一个 cpu2.msg， 并将 cpu2 添加到 msg/CMakeLists.txt 文件中
cpu2 简单定义一个变量: length
uint32 length
2.2 新建 publish 和 subscriber
在 drivers 目录下面新建 uorb_publish 目录 以及 uorb_subscriber 目录， 并新建对应的文件, 结构如下
├── uorb_publish
│ ├── CMakeLists.txt
│ └── uorb_publish.cpp
├── uorb_subscriber
│ ├── CMakeLists.txt
│ └── uorb_subscriber.cpp
uorb_publish/CMakeLists.txt
px4_add_module(
MODULE drivers__uorb_publish
MAIN uorb_publish
STACK_MAIN 1200
COMPILE_FLAGS
SRCS
uorb_publish.cpp
DEPENDS
)
uorb_publish/uorb_publish.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <poll.h>
#include <px4_log.h>
#include <uORB/uORB.h>
#include <uORB/topics/cpu2.h>
#include <px4_workqueue.h>
extern "C" __EXPORT int uorb_publish_main(int argc, char *argv[]);
static orb_advert_t cpu2_topic;
static uint8_t cnt = 0;
static struct work_s work;
static struct cpu2_s att;
static void cycle_trampoline(void *arg)
{
PX4_INFO("publish \n");
if (cpu2_topic == NULL)
{
cpu2_topic = orb_advertise(ORB_ID(cpu2), &att);
}
att.length = cnt;
cnt++;
if (cnt == 255) {
cnt = 0;
}
orb_publish(ORB_ID(cpu2), cpu2_topic, &att);
(void)work_queue(HPWORK, &work, (worker_t)&cycle_trampoline, nullptr, USEC2TICK(1000 * 1000));
}
int uorb_publish_main(int argc, char *argv[])
{
PX4_INFO(" uorb_publish \n");
work = {};
cpu2_topic = NULL;
memset(&att, 0 , sizeof(att));
(void)work_queue(HPWORK, &work, (worker_t)&cycle_trampoline, nullptr, 0);
return 0;
}
uorb_subscriber/CMakeLists.txt
px4_add_module(
MODULE drivers__uorb_subscriber
MAIN uorb_subscriber
STACK_MAIN 1200
COMPILE_FLAGS
SRCS
uorb_subscriber.cpp
DEPENDS
)
uorb_subscriber/uorb_subscriber.cpp
#include <poll.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <px4_log.h>
#include <uORB/topics/cpu2.h>
#include <uORB/uORB.h>
#include <px4_workqueue.h>
#include <drivers/device/device.h>
extern "C" __EXPORT int uorb_subscriber_main(int argc, char *argv[]);
static struct work_s work;
static int cpu2_fd = 0;
static struct cpu2_s att;
static void cycle_trampoline(void *arg)
{
// PX4_INFO("subscriber \n");
if (cpu2_fd == 0)
{
cpu2_fd = orb_subscribe(ORB_ID(cpu2));
}
bool updated = false;
updated = false;
if (orb_check(cpu2_fd, &updated) != PX4_OK)
{
return;
}
if (updated)
{
orb_copy(ORB_ID(cpu2), cpu2_fd, &att);
PX4_INFO("%d \n", att.length);
}
work_queue(HPWORK,
&work,
(worker_t)&cycle_trampoline,
nullptr,
USEC2TICK(1000 * 1000));
}
int uorb_subscriber_main(int argc, char *argv[])
{
work = {};
cpu2_fd = 0;
memset(&att, 0 , sizeof(att));
PX4_INFO("uorb_subscriber ");
(void)work_queue(HPWORK, &work, (worker_t)&cycle_trampoline, nullptr, 0);
return 0;
}
2.3 将publish 和 subscriber 添加到 configs 目录下对应的板子里面去 以及 编译运行
三、运行结果以及常见问题
-
编译烧录到板子后，在
nsh键入?， 会显示如下nsh> ? help usage: help [-v] [<cmd>] [ dirname false mkfatfs pwd true ? date free mkfifo rm uname basename dd help mkrd rmdir umount break df hexdump mh set unset cat echo kill mount sh usleep cd printf ls mv sleep xd cp exec mb mw test cmp exit mkdir ps time Builtin Apps: ... uorb uorb_publish uorb_subscriber ... nsh>如果未出现
uorb_publish与uorb_subscriber， 原因在于 未将publish 和 subscriber 添加到 configs 目录下对应的板子里面去; -
先启动
uorb_subscriber， 再启动uorb_publishnsh> uorb_subscriber INFO [uorb_subscriber] uorb_subscriber nsh> uorb_publish INFO [uorb_publish] uorb_publish INFO [uorb_publish] publish nsh> INFO [uorb_subscriber] 0 INFO [uorb_publish] publish INFO [uorb_subscriber] 1 INFO [uorb_publish] publish INFO [uorb_subscriber] 2 INFO [uorb_publish] publish INFO [uorb_subscriber] 3 INFO [uorb_publish] publish INFO [uorb_subscriber] 4 INFO [uorb_publish] publish INFO [uorb_subscriber] 5 INFO [uorb_publish] publish INFO [uorb_subscriber] 6 INFO [uorb_publish] publish .....
