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Original question:

How to disable UART hardware receive in AM335x?

AM3352: Disable UART0

Jacek Kryszyn
Prodigy 200 points
Part Number: AM3352


Hello,

I am maintaining an embedded system which I didn't develop. The core part of it is AM3352. I would like to block UART0. I don't want to allow sending anything to device using UART0, so basically blocking only UART_RX would be ok. How to achieve this?

In one of files with .patch extensions (I presume it is somehow applied during Linux build) I found something like that: 

+uart0_pins: pinmux_uart0_pins {
+    pintrl-single,pins = <
+        0x170 (PIN_INPUT_PULLUP | MUX_MODE0)    /* uart0_rxd.uart0_rxd */
+        0x174 (PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* uart0_txd.uart0_txd */
+    >;
+};
+
+&uart0 {
+    pinctrl-names = "default";
+    pinctrl-0 = <$uart0_pins>;
+    status = "okay";
+};

If I delete it/modify (how?) then my issue will be solved?

Best regards

  • 0
    TI__Guru**** 173781 points

    Hi Jacek,

    Which Processor SDK version do you use?

    The patch you mentioned is to enable UART0. Without this patch on your board DTS file, UART0 would be disabled already.

  • 0 in reply to Bin Liu
    Prodigy 200 points

    Regarding SDK: to be honest - I don't know. The project is based on Buildroot and there are just some bin and elf files included. I don't know much about it.

    Indeed, removing those lines did the trick and after kernel loads, the UART0 is dead, but this is not the exact thing I wanted. Actually, I wanted to disable any possibility to interrput the autoboot process by hitting any key using serial port connection. Is it possible?

  • 0 in reply to Jacek Kryszyn
    TI__Guru**** 173781 points

    Jacek Kryszyn said:
    Actually, I wanted to disable any possibility to interrput the autoboot process by hitting any key using serial port connection. Is it possible?

    Do you mean to not interrupt the U-Boot autoboot process? This is not what you asked in your first post. Please explain at which point your system boot process could be interrupted by key stroke? a boot log might help me to understand what you want.

    By the way, it would be difficult to support you without knowing the U-Boot/Kernel version. This forum only supports TI Processor SDK.