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TMDXIDK5718: How to use RS485 at J39 in MPU A15?

Leonid Titov
Prodigy 40 points
Part Number: TMDXIDK5718
Other Parts Discussed in Thread: PROFIBUS

Hi Team!

I found that data flow of UART2 is driven by AA3, but i cannot understand how can i control this pin? It is not available for control by GPIO on MPU.

Is it possible to use UART2 (J39) on MPU A15 core? on IPU M4?

Where i can found example of using this port?

  • 0
    TI__Genius 14680 points

    Leonid,

    The SoC pinmux needs to be configured to enable UART2 at the device pins. The pinmux tool can be found at https://www.ti.com/tool/PINMUXTOOL .

    The Processor SDK includes configurations for the development boards, including the AM571x IDK which you can find in <install_dir>\pdk_am57xx_1_0_16\packages\ti\board\src\idkAM571x.

    Best regards,

    Dave

  • 0 in reply to Dave Bell
    Prodigy 40 points

    Dave, thank you for the attention

    Yes, I use PinMix. And now I see that the UART2 pins are configured correctly. My question is about the output that drives DE/nRE - AA3.

    In the default configuration, pin AA3 is not configured. And can not be configured as Gpio.

    I would like to use this channel:

  • 0 in reply to Leonid Titov
    TI__Genius 14680 points

    Leonid,

    Thanks for your patience, and for clarifying your question. I see now that you're asking more specifically on the RS-485 operation and not simply UART2 enablement.

    The IDK was built to support the industrial communications capable on the device leveraging the PRU-ICSS subsystems, and the RS-485 port itself is leveraged in the Profibus slave protocol (available at ). 

    You can see from the schematic snippet that the GPIO signals are from the PRU-ICSS and not the SoC GPIO. So to manage these I/O you need to leverage PRU programming.


    For the AM571x, is there any reference SW for the RS-485 flow control with PRU? This is mentioned in the IDK user guide:
    >>>
    RS-485The AM572x IDK EVM contains an RS-485interfaceon 3-pinheader, J39. This is enabled by the SN65HVD78D Half-Duplex RS-485 Transceiver. The transceiver controls the half-duplex communication and also provides high-voltage transient protection. This interface is attached to the SOC-level UART2 port for RX and TX data. The UART TX data line is monitored by PR2_PRU1, so that PRU code can monitor TX activity and then control the DE and Ren lines into the transceiver.
    <<<

    And we have a whitepaper ( http://www.ti.com/lit/wp/spry265/spry265.pdf  ) proposing the same, however we don't have an example to leverage directly and the Profibus protocol is not available for general source release. For general PRU programming, you can refer to https://www.ti.com/lit/pdf/sprach5 .

    Best regards,

    Dave