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Linux/AM5718: About the RS485

rei
Mastermind 6155 points
Part Number: AM5718
Other Parts Discussed in Thread: TMDXIDK5718

Tool/software: Linux

Hi,
I'm trying to use RS485 (UART) in the following environment.

OS:Ubuntu 16.04.4 LTS
SDK:PROCESSOR-SDK-LINUX-RT-AM57X 05_02_00_10
EVM: TMDXIDK5718

Question1
Does RS485 (UART2) correspond to "/dev/ttyS1" on Linux?

Question2
I am using TMDXIDK57X-LCD.
Therefore am571x-idk-lcd-osd101t2587.dts is used,
Is RS-485 (UART2) recognized in this device tree?

And I am checking about Pinmux of RS485.

[sdk_install_dir]/board-support/u-boot-2018.01+gitAUTOINC+313dcd69c2^g313dcd69c2/board/ti/am57xx/mux_data.h

Question3
I look at TMDXIDK 5718 Schematic (Page. 29).
I think that the following description is incorrect.
Is this a mistake of OUTPUT?

Line 990: {MCASP5_ACLKX, (M12 | PIN_INPUT | MANUAL_MODE)}, /* mcasp5_aclkx.pr2_pru1_gpi1 */

Regards,
Rei

  • 0
    TI__Guru**** 167581 points
    Hi Rei,

    rei said:
    Question1
    Does RS485 (UART2) correspond to "/dev/ttyS1" on Linux?


    Yes. All these node indexes are defined as in serial aliases in dra7.dtsi.

    rei said:
    Question2
    I am using TMDXIDK57X-LCD.
    Therefore am571x-idk-lcd-osd101t2587.dts is used,
    Is RS-485 (UART2) recognized in this device tree?


    Yes. UART2 is defined in dra7.dtsi, which is indirectly included in am572x-idk-lcd-osd101t2587.dts.

    rei said:
    Question3
    I look at TMDXIDK 5718 Schematic (Page. 29).
    I think that the following description is incorrect.
    Is this a mistake of OUTPUT?


    Probably it is a mistake. However, you cannot directly correct the pinmux setting and use RS485 in Linux. This pin is a PRU pin, not a GPIO. This IDK board design was done a few years ago, and intended to use PRU to control the RS485 direction, but the function is not supported in Processor SDK.