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Original question:

ISO3082: ISO3082 working in single direction

ISO3082: <break> and data loss problem with ISO3082

Tech Atreyo
Prodigy 20 points
Part Number: ISO3082
Other Parts Discussed in Thread: ISO485EVM, ISO1410DWEVM, ISO1410

Hi,

I am using ISO3082DWG4 for my RS485 circuit. In that, We define chip characteristics in .dts file as per below.

After that, when we establish connection between module and laptop below observation is noted.

Observation: Once we established connection successfully and start sending data using my laptop(running terminal application) to our RS485 module(running cutecom application), we are able to do send receive data from both side but when we send anything from board to laptop it will also send echo of internally. 

Please check below image file which converter we are using to connect laptop.

Also suggest me ideal schemetic for  ISO3082DWG4.

  • 0
    Prodigy 20 points

    Please check my dts file configuration.

    &uart1 {
    pinctrl-names = "default";
    pinctrl-0 = <&pins_uart1>;
    linux,rs485-enabled-at-boot-time;
    rs485-rts-delay = <5 5>;
    rts-gpios = <&pctl 10 GPIO_ACTIVE_HIGH>;
    status = "okay";
    };

    pins_uart1: pins_uart1 {
    sppctl,pins = <
    SPPCTL_IOPAD(11,SPPCTL_PCTL_G_PMUX,MUXF_UA1_TX,0)
    SPPCTL_IOPAD(12,SPPCTL_PCTL_G_PMUX,MUXF_UA1_RX,0)
    SPPCTL_IOPAD(10,SPPCTL_PCTL_G_GPIO,0,SPPCTL_PCTL_L_OUT)
    >;
    };

  • 0 in reply to Tech Atreyo
    TI__Guru 53855 points

    Hi,

    Thanks for reaching out and sorry to hear about the issue.

    I think I understand the problem that you have described but I would like to clarify that ISO3082 is only a physical layer device and all it does is convert logic signal voltage levels to RS-485 compatible voltage levels and vice-versa and it doesn't process or try to understand what data is being sent. Hence, I do not believe ISO3082 will lead to the issue you are describing. 

    ISO3082 does introduce some propagation delay which needs to be budgeted into the code, if that's taken care then ISO3082 shouldn't really be leading any communication issues, assuming the schematic and PCB layout follow the standard guidelines for them to work normal.

    Please do share the schematic and PCB layout so that I can review them and confirm if there is any issue in these.

    Tech Atreyo said:
    Also suggest me ideal schemetic for  ISO3082DWG4.

    You can refer to ISO485EVM for an example RS-485 schematic to ISO3082. Since is also pin-compatible the latest RS-485 device ISO1410, you could as well refer to ISO1410DWEVM. Thanks.

    https://www.ti.com/tool/ISO485EVM

    https://www.ti.com/tool/ISO1410DWEVM


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 20 points

    Hello sir,

    We added delay while defining property(rs485-rts-delay = <5 5>;) of the RS485 in kernel. We also checked with increase and decrease the delay but still not able to get proper and continue data.

    https://www.ti.com/tool/ISO1410DWEVM - Can we refer same schematic for our ISO3082?

  • 0 in reply to Tech Atreyo
    TI__Guru 53855 points

    Hi Atreya,

    Thanks for confirming that you have already tried increasing and decreasing the delay to cover for ISO3082 added propagation delay into overall system.

    Yes, ISO1410DWEVM schematic can be considered as a reference circuit for ISO3082 as well.

    Like I mentioned earlier, I do not ISO3082 to be the cause of the issue as it is only a voltage levels converting transceiver. If adding the isolator into the system is leading to the issue then that would be because of incorrect budgeting of isolator delay into the code/tool. To verify if isolator is causing any issue, I would recommend you to check the input and output waveforms of ISO3082 and see if there is any logic mismatch caused by the isolator. If you do not see any mismatch, then the issue lies elsewhere in the system even though addition of ISO3082 is causing the issue.

    Let me know if you have any further questions, thanks.


    Regards,
    Koteshwar Rao