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BeagleBone Black UART

Dileep D R
Intellectual 620 points

I am trying to enable UART4 modifying DTS file, but still no /dev/ttyO4 found.

Kernel : 4.1

    uart4_pins: pinmux_uart4_pins {
        pinctrl-single,pins = <
            0x70 (PIN_INPUT_PULLUP | MUX_MODE6)    /* uart4_rxd.uart4_rxd */
            0x74 (PIN_OUTPUT_PULLDOWN | MUX_MODE6)    /* uart4_txd.uart4_txd */
        >;
    };

&uart4 {
    pinctrl-names = "default";
    pinctrl-0 = <&uart4_pins>;

    status = "okay";
};

  • 0
    TI__Guru**** 393215 points
    Hi,

    I will ask the SW team to look at your DTS settings. Note that kernel v4.1 is not supported by TI at present.
  • 0 in reply to Biser Gatchev-XID
    TI__Guru 55345 points

    Hello Dileep,

    Could you share the output of this command:

    root@am335x-evm:~# dmesg | grep tty


    Best regards,
    Kemal

  • 0 in reply to Kemal R. Shakir
    Intellectual 620 points

    Thanks guys for your support. Initially I thought UART4 will be mapped to /dev/ttyO4, but actually it is mapped to /dev/ttyS4.

    root@arm:~# dmesg | grep tty
    [    0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=192.168.0.103:/home/dileep/BeagleBone/rootfs_debian ip=1920
    [    0.000461] WARNING: Your 'console=ttyO0' has been replaced by 'ttyS0'
    [    3.004694] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 155, base_baud = 3000000) is a 8250
    [    3.900551] console [ttyS0] enabled
    [    3.905163] 481a8000.serial: ttyS4 at MMIO 0x481a8000 (irq = 156, base_baud = 3000000) is a 8250
    [   10.056839] systemd[1]: Expecting device dev-ttyS0.device...
    [   10.972721] systemd[1]: Starting system-getty.slice.
    [   11.023044] systemd[1]: Created slice system-getty.slice.
    [   11.052669] systemd[1]: Starting system-serial\x2dgetty.slice.
    [   11.089042] systemd[1]: Created slice system-serial\x2dgetty.slice.