# 在 Raspberry Pi OS 上使用 PilotPi
## 开发者快速指南
### 操作系统映像
The latest official [Raspberry Pi OS Lite](https://downloads.raspberrypi.org/raspios_lite_armhf_latest) image is always recommended.
默认你已经通过ssh连接到了树莓派。
### 设置快速访问(可选)
#### 主机名和 mDNS
mDNS helps you connect to your RPi with hostname instead of IP address.
```sh
sudo raspi-config
```
Navigate to **Network Options > Hostname**.
设置并退出。
You may want to setup [passwordless auth](https://www.raspberrypi.org/documentation/remote-access/ssh/passwordless.md) as well.
### 配置操作系统
#### config.txt
```sh
sudo nano /boot/config.txt
```
将文件内容替换为：
```sh
# enable sc16is752 overlay
dtoverlay=sc16is752-spi1
# enable I2C-1 and set the frequency to 400KHz
dtparam=i2c_arm=on,i2c_arm_baudrate=400000
# enable spidev0.0
dtparam=spi=on
# enable RC input
enable_uart=1
# enable I2C-0
dtparam=i2c_vc=on
# switch Bluetooth to miniuart
dtoverlay=miniuart-bt
```
#### cmdline.txt
```sh
sudo raspi-config
```
**Interfacing Options > Serial > login shell = No > hardware = Yes**.
启用 UART 但禁用登陆shell。
```sh
sudo nano /boot/cmdline.txt
```
Append `isolcpus=2` after the last word.
整个文件将是：
```sh
console=tty1 root=PARTUUID=xxxxxxxx-xx rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait isolcpus=2
```
这告诉 Linux 内核不要在 CPU 核心2 上调度任何进程。
我们将在稍后手动在该核心运行 PX4。
Reboot and SSH onto your RPi.
检查串口：
```sh
ls /dev/tty*
```
There should be `/dev/ttyAMA0`, `/dev/ttySC0` and `/dev/ttySC1`.
检查 I2C：
```sh
ls /dev/i2c*
```
There should be `/dev/i2c-0` and `/dev/i2c-1`
检查SPI：
```sh
ls /dev/spidev*
```
There should be `/dev/spidev0.0`.
#### rc.local
In this section we will configure the auto-start script in **rc.local**.
```sh
sudo nano /etc/rc.local
```
Append below content to the file above `exit 0`:
```sh
echo "25" > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio25/direction
if [ $(cat /sys/class/gpio/gpio25/value) -eq 1 ] ; then
echo "Launching PX4"
cd /home/pi/px4 ; nohup taskset -c 2 ./bin/px4 -d -s pilotpi_mc.config 2 &> 1 > /home/pi/px4/px4.log &
fi
echo "25" > /sys/class/gpio/unexport
```
保存并退出。
:::info
Don't forget to turn off the switch when it is not needed.
:::
#### CSI 相机
:::info
Enable CSI camera will stop anything works on I2C-0.
:::
```sh
sudo raspi-config
```
**Interfacing Options > Camera**
### 构建代码
To get the _very latest_ version onto your computer, enter the following command into a terminal:
```sh
git clone https://github.com/PX4/PX4-Autopilot.git --recursive
```
:::info
This is all you need to do just to build the latest code.
:::
#### 为 Raspberry Pi OS 交叉编译
然后上传：
```sh
export AUTOPILOT_HOST=192.168.X.X
```
或
```sh
export AUTOPILOT_HOST=pi_hostname.local
```
PX4 已配置使用多旋翼模型启动。
```sh
cd PX4-Autopilot
make scumaker_pilotpi_default
```
Then upload it with:
```sh
make scumaker_pilotpi_default upload
```
这时应当使用基于 Docker 的编译。
```sh
cd px4
sudo taskset -c 2 ./bin/px4 -s pilotpi_mc.config
```
在执行下一步之前，先清除现有构建目录：
If you encountered the similar problem executing `bin/px4` on your Pi as following:
```
bin/px4: /lib/xxxx/xxxx: version `GLIBC_2.29' not found (required by bin/px4)
```
如果您是首次使用 Docker 进行编译，请参考官方说明。
在 PX4-Autopilot 文件夹下执行：
```sh
rm -rf build/scumaker_pilotpi_default
```
### 备选构建方法 (使用 docker)
只是为了编译代码，则可以执行：
If you are compiling for the first time with docker, please refer to the [official docs](../test_and_ci/docker.md#prerequisites).
混控器在 pilotpi_xx.conf 文件中启用：
```sh
./Tools/docker_run.sh "export AUTOPILOT_HOST=192.168.X.X; export NO_NINJA_BUILD=1; make scumaker_pilotpi_default upload"
```
:::info
mDNS is not supported within docker. 您也可以自己创建一个。
:::
:::info
If your IDE doesn't support ninja build, `NO_NINJA_BUILD=1` option will help.
You can compile without uploading too. Just remove `upload` target.
:::
It is also possible to just compile the code with command:
```sh
./Tools/docker_run.sh "make scumaker_pilotpi_default"
```
### 后期配置
示例输出
#### Actuator Configuration
First set the [CA_AIRFRAME](../advanced_config/parameter_reference.md#CA_AIRFRAME) parameter for your vehicle.
You will then be able to assign outputs using the normal [Actuator Configuration](../config/actuators.md) configuration screen (an output tab will appear for the RPi PWM output driver).
#### External Compass
In the startup script(`*.config`), you will find
```sh
# external GPS & compass
gps start -d /dev/ttySC0 -i uart -p ubx -s
#hmc5883 start -X
#ist8310 start -X
```
Uncomment the correct one for your case.
Not sure which compass comes up with your GPS module? Execute the following commands and see the output:
```sh
sudo apt-get update
sudo apt-get install i2c-tools
i2cdetect -y 0
```
Sample output:
```
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- 0e --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1e --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
```
`1e` indicates a HMC5883 based compass is mounted on external I2C bus. Similarly, IST8310 has a value of `0e`.
:::info
Generally you only have one of them.
Other devices will also be displayed here if they are connected to external I2C bus.(`/dev/i2c-0`)
:::