Using only UART communications for X-Port control through Raspberry Pi Zero 2W

[jenicekneuvirt]

I would like to ask if it is possible to use it to control the gimbal only via serial communication from the Raspberry Pi, even though I probably do not have a properly created USB bulk. I tried to create and mount it, but I was unable to complete the configuration according to the instructions.
In the example files I have reset
#define CONFIG_HARDWARE_CONNECTION DJI_USE_ONLY_UART
and also
#define LINUX_UART_DEV1 "/dev/ttyUSB0"
#define USB_UART_CONNECTED_TO_UAV_VID (0x10C4)
#define USB_UART_CONNECTED_TO_UAV_PID (0xEA60)

I have the following connection:
powering USB-C -> X-port -> adapter board -> USB-TTL converter -> Raspberry Pi Zero 2W

I tried to run the compiled PSDK and this error was returned:
0.046 core [Info] dji_core.c:110 Payload SDK Version : V3.13.1-beta.0-build.2277 Sep 16 2025 16:29:14
5.236 adapter [Info] dji_access_adapter.c:358 Try identify UART0 connection failed. Probably because SDK adapter or aircraft not finish init or UART connect error.

Is this error possible because the drone is not connected to the rest of the hardware?
My teacher said that I should move the gimbal without needing the drone itself for development. I just got this HW and the subsequent testing will be on the Matrice 350

[dji-dev]

Agent comment from ZIXUAN LIU in Zendesk ticket #171264:

Dear developer,

Hello, thank you for contacting DJI Innovations.

Thank you for your patience. Regarding hardware connection, you can refer to: https://sdk-forum.dji.net/hc/zh-cn/articles/50341690206105-PSDK-%E5%90%84%E6%9C%BA%E5%9E%8B%E7%A1%AC%E4%BB%B6%E8%BF%9E%E6%8E%A5%E4%BB%8B%E7%BB%8D
The configuration file can refer to: https://developer.dji.com/doc/payload-sdk-tutorial/en/payload-quick-start/run-sample-code.html

Regarding your error, it is a problem with the serial port not working. You can check the following steps:
a. Firstly, confirm if the hardware connection is correct and if it has been connected according to the official instructions. Check if the RX TX is reversed and if the dip switch is in place.
b. Check the configuration in dji_sdk_config. h, for models like M400, it is necessary to investigate this issue. Different connection methods require different software configurations. For example, if connected according to DJI_USE-ONLY1 UART and configured as DJI_USE-ONLY1 USB_SULK_DEVICE, this problem may also occur.
c. Compatibility issue with onboard serial port. If using an onboard serial port, it is recommended to replace it with FT232 or CP2102 to verify if there is any impact from the onboard serial port.
d. Confirm in hal_uart. h whether the configured port is the same as the actual port used.
e. You can replace the development board or run the PSDK program with a Windows virtual machine/Linux device to see if it runs successfully, which can indirectly verify whether it is a device issue.

Thank you for your support of DJI products! Wishing you all the best!

Best Regards,
DJI DJI Innovation SDK Technical Support

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