Jetson 09 Automatic Command Execution upon Booting

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This tutorial is aimed at demonstrating how the host controller automatically executes specific commands and communicates instructions to the slave device each time the system boots. The code blocks in this chapter are for comprehension only and are not executable. They serve to elucidate the automatic processes that the product undertakes upon startup. Should you find the need, these commands are subject to modification or expansion.

cmd_on_boot() Function

The cmd_on_boot() function, located within the main program of the product, defines a list of commands to be executed at startup. These commands facilitate initial configurations and set up essential operational parameters for the device. 

def cmd_on_boot():
    # List of commands to be executed at startup 
    cmd_list = [
        'base -c {"T":142,"cmd":50}',   # set feedback interval
        'base -c {"T":131,"cmd":1}',    # serial feedback flow on
        'base -c {"T":143,"cmd":0}',    # serial echo off
        'base -c {"T":4,"cmd":2}',      # select the module - 0:None 1:RoArm-M2-S 2:Gimbal
        'base -c {"T":300,"mode":0,"mac":"EF:EF:EF:EF:EF:EF"}',  # the base won't be ctrl by esp-now broadcast cmd, but it can still recv broadcast megs.
        'send -a -b'    # add broadcast mac addr to peer
    ]
    # Iterate through the list of commands
    for i in range(0, len(cmd_list)):
        camera.cmd_process(cmd_list[i])

The control unit of the product can perform certain functional controls via command line instructions, similar to the base -c command shown above. These commands are designed to directly pass JSON instructions written afterwards through the Jetson's GPIO serial port to the slave device. We will further explain the meaning of the default automatic boot-up commands.

  • base -c {"T":142,"cmd":50}

Sets the extra interval time for the slave device to continuously feedback information. The unit for the cmd value is milliseconds. This feature is used to reduce the frequency of feedback information from the slave controller, aiming to alleviate the computational pressure on the control unit from processing this feedback.

  • base -c {"T":131,"cmd":1}

Turns on the continuous information feedback feature of the sub-controller. Once enabled, the control unit does not need to fetch information from the sub-controller in a query-response manner. Although this feature is normally enabled by default on the sub-controller, we send the command again to ensure it's activated.

  • base -c {"T":143,"cmd":0}

Turns off the serial command echo. This way, when the control unit sends instructions to the sub-controller, the latter will not feedback on the received instructions to the control unit, preventing the control unit from processing unnecessary information.

  • base -c {"T":4,"cmd":2}

Sets the type of the external module. A cmd value of 0 indicates no external module is connected; 1 stands for a robotic arm; and 2 for the pan-tilt. If your product does not have a pan-tilt or robotic arm installed, this value should be changed to 0.

  • base -c {"T":300,"mode":0,"mac":"EF:EF:EF:EF:EF:EF"}

Prevents the chassis from being controlled by ESP-NOW broadcasts from other devices, except for devices with the specified MAC address. You can make up a MAC address or use the MAC address of your own ESP32 remote controller.

  • send -a -b

Adds the broadcast address (FF:FF:FF:FF:FF:FF) to peers, enabling you to subsequently send broadcast messages directly to other devices via broadcast signals.

You can learn about other host computer command line instructions in the following WEB command line application chapters.

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