In JetPack4,6_R32.6.1, serial@c280000 can send data, but can not recieve data with RS484. But JetPack4.5_R32.5.1 can work

Dear All:

  • 1: In our custom board with Jetson TX2-NX SOM.

  • 2: In JetPack4.5_R32.6.1, RS485 can work normal(recieve data or send data)
    In JetPack4.6_R32.6.1, RS485 just can send data, can not recieve data

  • 3: Enable TX2-NX with /Linux_for_Tegra/bootloader/tegra186-p3636-0001-p3509-0000-a01.dtb

    • serial@c280000 {
    •   compatible = "nvidia,tegra186-hsuart";
    •   status = "okay";
    • };
  • 4: Remove following code from bpmp-dtb port with /Linux_for_Tegra/bootloader/t186ref/tegra186-bpmp-p3636-0001-a00-00.dtb,

    • serial {
    •   port = <3>;
    •   has_input;
    • };
      Result: RS485 can not recieve data
  • 5: Change bpmp-dtb port with /Linux_for_Tegra/bootloader/t186ref/tegra186-bpmp-p3636-0001-a00-00.dtb

    • serial {
    •   port = <0XFF>;
    •   has_input;
    • };
      Result: RS485 can not recieve data

    So, Could you provide some advices for this bug?Thank you very much.
    Best regards!!!

hello 848145724,

those bpmp changes were used to disable BPMP logs,
had you revise the bpmp-dtb and re-flash the target as following, $ sudo ./ -r -k bpmp-fw-dtb jetson-xavier-nx-devkit-tx2-nx mmcblk0p1

Remove or change bpmp-dtb port with /Linux_for_Tegra/bootloader/t186ref/tegra186-bpmp-p3636-0001-a00-00.dtb

when: sudo ./ -r -k bpmp-fw-dtb jetson-xavier-nx-devkit-tx2-nx external , flash end with errors like following picture:


hello 848145724,

it looks the communication issue,
may I know what does $ lsusb shows when you putting device enter forced-recovery mode?

After * I reextracted the driver installation package, following problem disapper.

But everif sudo ./ -r -k bpmp-fw-dtb jetson-xavier-nx-devkit-tx2-nx external success,
RS485 can only send data, can not reciere data.

hello 848145724,

may I know how you check the Tx/Rx, did you use the serial port utility?
is it possible to probe the signaling to analysis this from the hardware side?

1 Like

In custom board with Jetson tx2-nx(same custom board, same Jetson-tx2-nx SOM)

  • flash to JetPack4.5_R32.5.1, RS485 work normally(can send data and recieve data)

  • flash to JetPack4.6_R32.6.0, RS485 just can send data, can not recieve data.

With the same name files, and change same context.

  • Linux_for_Tegra/bootloader/t186ref/tegra186-bpmp-p3636-0001-a00-00.dtb,
  • Linux_for_Tegra/bootloader/tegra186-p3636-0001-p3509-0000-a01.dtb

Hello JerryChang.
first, I’m sorry this is our problem.
our hardware engineer found instability voltage cause this problem.
so after repaire hardware RS485 can send or recieve data.
Thank you very much.

glad to know it works, thanks for the feedback.

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