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[ADV7281A-M] Required register settings when input is selected.

Hi,

I have two questions about required settings when input is selected.
I summarized the questions to an attached file "Question_ADV7281A_M_register_setting_for_input_select.xlsx".
Please refer it.

Thank you!
Best regards.
Tamu
XLSX

Parents
  • Hi Tamu San,

            As per expert comment "If changing video mode for example changing from differential CVBS to single ended CVBS then we need to do a software reset of the ADV728x by writing 0x80 to User Map register 0x0F & we have to perform ADI recommended script.  
           If you are not changing video mode for example switching from Differential In Ain1,2 to Differential In Ain 3,4 then a software reset of the ADV728x is not needed. Also you can simply change the INSEL register instead of running a script.

    Please refer below expert comment procedure when changing the video mode,
    In the mentioned thread, you have discussed with part specialist https://ez.analog.com/video/f/q-a/6953/mipi-csi-2-tx-power-up-down-sequence-of-adv7282-m


                        -  Turn off the MIPI CSI-2 output off using the CSITX_PWRDWN bit.
                        -  If changing video mode [e.g. changing from differential CVBS to single ended CVBS] do a software reset of the ADV728x by writing 0x80 to User Map register 0x0F. Then perform ADI recommended script.
                         - If you are not changing video mode [e.g. switching from single ended CVBS on Ain1 to  single ended CVBSon Ain2] or differential to differential  then a software reset of the ADV728x is not needed. Also you can simply change the INSEL register instead of running a script.
                        - Turn on the MIPI CSI-2 output from the ADV728x by using the CSITX_PWRDWN bit.

    Thanks,

    Poornima

  • Hi Poornima-san,

    Thank you for your reply.

    Of course, I have understood the expert comment at the thread you indicated: ez.analog.com/.../mipi-csi-2-tx-power-up-down-sequence-of-adv7282-m
    because it was my question.

    As I mentioned in my attached file "Question_ADV7281A_M_register_setting_for_input_select.xlsx",
    in this case, switching from Differential In Ain1,2 to Differential In Ain 3,4.
    And my customer has to use "Fast Switch Script" because their project is for Automotive application.

    Actually, my customer tried to simply change the INSEL register when switching from Differential In Ain1,2 to Differential In Ain 3,4,
    then, it caused it took over 2 seconds until it had locked and he can see the video at the display.
    So he should use "Fast Switch Script", but we don't know which settings are OK at only initial setting and we don't know which settings are also required at input select in the "Fast Switch Script".
    So I asked two questions at this time.

    Please refer the attached file "Question_ADV7281A_M_register_setting_for_input_select.xlsx",
    and could you answer the question 1 and 2 in the file?

    Thank you!
    Best regards.
    Tamu

  • Hi Tamu San,

            I believe, If switching input from Differential In Ain1,2 to Differential In Ain 3,4 we can change only the INSEL register instead of configuring the remaining registers because the remaining configuration is already configured when we give differential input to AIN 1,2.

      Note:  When using fast switching mode it can take up to 250 ms to switch from one single ended CVBS input to another single ended CVBS input or  Differential input.
    If you are switching from a single ended CVBS input to differential CVBS (or YC or YPbPr) inputs, I advise performing a software reset, wait 10 ms and then program the ADV7281 with a recommended differential CVBS script ( or YC script or YPbPr script).

    Thanks,

    Poornima

  • Hi Poornima-san,

    Thank you for your reply.

    About your comment:
    >I believe, If switching input from Differential In Ain1,2 to Differential In Ain 3,4 we can change only the INSEL register instead of configuring the remaining registers
    >because the remaining configuration is already configured when we give differential input to AIN 1,2.

    The "Fast Switch script" includes settings which makes wait time of the clamp a zero, and also includes settings to undo the "clamp wait time".
    So I think that some of the settings in "Fast Switch script" are required when switching from Differential In Ain1,2 to Differential In Ain 3,4, even if the fast switch settings are already configured at the initial sequence.

    Actually, my customer simply changed the INSEL register when switching from Differential In Ain1,2 to Differential In Ain 3,4, then, it caused it took over 2 seconds until it had locked and he could see the video at the display.
    Also actually, he included some of the "fast switch" settings are set again when changed the INSEL register when switching from Differential In Ain1,2 to Differential In Ain 3,4, then, it improved the lock time and it took about 1 second until it had locked and he could see the video at the display.
    So, it's not allowed that simply changing the INSEL register when switching from Differential In Ain1,2 to Differential In Ain 3,4.

    But we don't know which are necessary re-settings and which are unnecessary re-settings in the fast switch script when switching from Differential In Ain1,2 to Differential In Ain 3,4.
    So I have been asking the questions.

    Please refer the attached file "Question_ADV7281A_M_register_setting_for_input_select.xlsx".
    Could you answer the question 1 and 2 in the file?

    Thank you!
    Best regards.
    Tamu

  • Hi Tamu San,

             Here we don't have ADV728xA-M eval board to verify which configuration are required other than INSEL register to check video lock delay.

             As  per RSD document, the following writes should be performed when the user perform fast switch mode and by referring your attached configuration document according to question 2 you have enabled the below configuration.

    So I beleive your settings are good and enough for supporting fast switch mode when changing differential CVBS input .

                            42 0E 80 ADI Required Write; Reset Current Clamp Circuitry (step1)
                            42 9C 00 ADI Required Write; Reset Current Clamp Circuitry (step2)
                            42 9C FF ADI Required Write; Reset Current Clamp Circuitry (step3)
                            42 0E 00 ADI Required Write; Reset Current Clamp Circuitry (step4)
                            42 0E 80 ADI Required Write [Fast Switch]
                            42 D9 44 ADI Required Write [Fast Switch]
                            42 0E 40 Enter User Sub Map 2 [Fast Switch]
                            42 E0 01 Enable Fast Switch Mode [Fast Switch]
                            42 0E 00 Enter User Sub Map [Fast Switch]            


    Thanks,

    Poornima

Reply
  • Hi Tamu San,

             Here we don't have ADV728xA-M eval board to verify which configuration are required other than INSEL register to check video lock delay.

             As  per RSD document, the following writes should be performed when the user perform fast switch mode and by referring your attached configuration document according to question 2 you have enabled the below configuration.

    So I beleive your settings are good and enough for supporting fast switch mode when changing differential CVBS input .

                            42 0E 80 ADI Required Write; Reset Current Clamp Circuitry (step1)
                            42 9C 00 ADI Required Write; Reset Current Clamp Circuitry (step2)
                            42 9C FF ADI Required Write; Reset Current Clamp Circuitry (step3)
                            42 0E 00 ADI Required Write; Reset Current Clamp Circuitry (step4)
                            42 0E 80 ADI Required Write [Fast Switch]
                            42 D9 44 ADI Required Write [Fast Switch]
                            42 0E 40 Enter User Sub Map 2 [Fast Switch]
                            42 E0 01 Enable Fast Switch Mode [Fast Switch]
                            42 0E 00 Enter User Sub Map [Fast Switch]            


    Thanks,

    Poornima

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