PX4IO开发者的第一课

这个教程深入地讲解了如何开箱检验、安装和配置PX4IO板子。本教程假设你已经成功地完成了PX4FMU的设置

开箱和初始配置

按照顺序进行本节的每一个步骤至关重要!

所需材料

  • PX4FMU
  • PX4IO
  • 手动开关
  • 舵机
  • 遥控接收机
  • USB线
  • microSD或microSDHC卡和读卡器
  • 至少一个FTDI 3.3V串口线

选用材料

  • 蜂鸣器
  • 数传系统如 Xbee 或 3DR

PX4IO首次拆封和检查

  • 采取所有必要的防静电手段打开装有PX4IO板子的包裹,检查板子两面是否存在器件缺失、焊接不充分和接口针脚弯曲等问题。
  • 特别要注意中所示的两个电阻和中所示的两个电容上的焊点。。
  • 一旦你板子有肉眼可察的问题,请联系3DR客服报告生产失误或Should you have a board with any visually confirmed issues then please either contact 3DR customer services to report a manufacturing fault or refer to the “Voodoo” section at the end of the guide for possible fixes and / or workarounds.

PX4IO电路板设置

  • 焊接servo/PPM 插针 (9 x 3 的直角插针) 到 IO 电路板.
  • 请注意,第一个位置是用于接收器连接,其余1-8连接servos .
  • 可选: 焊接S-Bus信号插针,使用一排3的直角插针焊接到电路板上.
  • 可选: 焊接一个外接电源插针到电路板(否则只能由USB给FMU供电)
  • 连接设防开关.
  • 可选:连接蜂鸣器.

Connect the FMU and the IO

  • Mount the boards on top of each other.
  • If you have some 15mm or longer M3 plastic screws and plastic nuts then bolt the boards together using the provided white 8mm spacers.

Connecting the Receiver and Servo

  • Connect your receiver to the the first position on the 9 position header or add a Spektrum satellite receiver to the 3-pin socket marked SPEKTRUM IN in the board layout.
  • Connect a servo to servo connector #1

Update the Firmware

Prepare the MicroSD Card

  • Use this standard PX4IO startup file as a starter point for getting the FMU and IO working together and copy it to /etc/rc on your MicroSD card.
  • Make sure that the mixer file (.mix) defined in the startup script is present on your MicroSD card under /etc/mixer, the best would be if you copy (or re-copy) all files within the project directory ROMFS/mixers.
  • Once the board is working you can select an appropriate mixer file that suits your airframe.

Ground Control System Installation

  • Download either QGroundControl from here or APM Mission Planner from here.
  • Follow installation instructions for QGroundControl here or Mission Planner here.
  • Connect the PX4FMU / PX4IO combination to the ground control system using MAVLINK and telemetry radio or FTDI.

Calibration

Sensor Calibration

  • Perform the sensor calibration process as detailed here.

Radio Control Calibration

  • Perform the RC calibration as detailed here.

Manual Override Setup

  • Make sure channel 5 on your transmitter is assigned to a 3 way switch.
  • Open QGroundControl and make sure that manual mode can be enabled by checking the status in QGroundControl.

Testing

  • Make sure the MicroSD card is inserted into the PX4FMU.
  • Make sure you have a connection between the PX4 and your QGroundControl (FTDI cable or XBee)
  • Turn on your transmitter.
  • Power the board via USB (or externally if you set that up already).
  • The IO arming switch should now be on but not blinking.
  • Verify that the PX4 has connected to QGroundControl.
  • Switch to manual mode using your override switch on channel 5 on the transmitter.
  • Arm the FMU by clicking on the Arm button in QgroundControl or by moving the throttle / yaw stick to the bottow right corner. The IO arming switch should now be blinking slowly.
  • Arm the IO board by pressing the arming switch button for a few seconds. The IO arming switch should now repeatedly blink two times fast and then pause (like aircraft lights do).
  • Move your servo sticks around. One of them should move the servo arm.
  • Disarm the FMU by clicking the “Disarm System” button in QGC or by moving the throttle / yaw stick to the bottom left corner.

Parameters

  • Certain parameters like MAV-TYPE must be set correctly before control output will be observed.
  • Parameters are set on the FMU / IO by using the Onboard Parameters Tool Widget in QGC.
  • On connecting to the FMU by “adding a Link” in QGC all the stored parameters are transmitted to QGC and are displayed in the parameters tree in the widget.
  • These parameters can be refreshed at any time by pressing the “Get” button, and after making changes can be saved back to the FMU by clicking the “Set” button.
  • In order to store the parameters in non-volatile memory and prevent their loss during a reboot click the “Write (ROM)” button.
  • Further information on available / custom parameters and their meaning please refer here.

Auto-starting Flight Control Applications

  • Refer to this page for further information on starting the flight control applications from a user configurable script.

Initial Multirotor PID Tuning

  • In order for the FMU / IO combination to allow flight controls and to override in-built safety mechanisms the stage must be performed before any control output will be observed.
  • To perform tuning please follow these instructions.

First Flight

  • The PX4 system can control a variety of different vehicles and supports these flight modes.
  • During flight the system status is displayed using the various in-built LED’s, the meaning of the various indications is detailed here.
  • Some suggestions for powering the system in a “live” environment can be found here.

Voodoo

Repairing the missing resistor problem

  • Some boards have shown a manufacturing issue whereby 2 x 0ohm resistors are missing from the board. This situation is repairable but requires a VERY STEADY hand and fine soldering iron tip.
  • With the board securely held carefully melt the existing solder present around the connector posts, it is then possible to “drag” the solder between the 2 posts and complete the connection.

Care must be taken not to cause a short circuit or damage the board with excess heat.

Repairing the faulty capacitor connections problem

  • Some boards have shown a manufacturing issue whereby the 2 capacitors shown in section 1 have connections that are not quite completely soldered.
  • It is possible with a VERY STEADY hand and fine soldering iron tip to melt the existing solder on the pad at the end of the capacitor and properly complete the connection.

Care must be taken not to damage the component with excess heat.

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