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TMS320DM8168: RSEN signal importance for HDMI working

Bhasha Vyas
Prodigy 110 points
Part Number: TMS320DM8168
Other Parts Discussed in Thread: TXS0102, DM8107

Hi all,

We  have been  facing a issue in one the device which uses DM8168 processor.

When we connect the HDMI cable to the port , Video is working OK but audio is not working.

On study of technical manual found that there is system status register (SYS_STAT) which can be read to find the  status of HDMI detection.bit#2 for the register in for RSEN.

What is the significance of RSEN  ? How is it depended to the hardware connection of HDMI port? From where is this signal generated?

Please do help

Regards, 

Bhasha.

  • 0
    TI__Guru**** 170625 points
    Hi Bhasha,

    RSEN indicates that there is a receiver detected. If RSEN is not active then it is unlikely anything else will function.

    RSEN is documented in DM816x TRM. For additional info regarding HDMI RSEN, you might check HDMI 1.3a spec.

    See also below e2e threads:

    e2e.ti.com/.../180091
    e2e.ti.com/.../257973

    Regards,
    Pavel
  • 0 in reply to Pavel Botev
    Prodigy 110 points
    Hi Pavel,

    Thanks for your reply,

    I have checked the threads referenced by you above,

    In our design we are not using any such HDMI protection chip. For the differential line of HDMi we are using Common mode choke with ESD protection , TXS0102 Transciever IC for I2C lines and resistor divider for HP and CEC lines( as the DM8107 Processor's HP and CEC lines are not 5V tolerant.

    We are using similar design with DM8168 in our other design which works firne and or reading the SYS_STAT register we get "87" on HDMI cable insertion. But, We get "83" with DM8107.


    Also is there any document which can explain the Rsen signal generation and other related information.

    Please do give link for document if any.

    Similar design
  • 0 in reply to Bhasha Vyas
    TI__Guru**** 170625 points
    Bhasha,

    Seems like you have a HW malfunction of your custom board. I can not find any (other than TRM) documentation which provides more info regarding RSEN signal.

    What I can suggest you is to double check DM816x datasheet (section 9.9 HDMI). Check also DM816x silicon errata (Advisories 2.1.35, 2.1.57, 1.1.27, 1.0.14).

    Make sure also you are using the latest PSP 04.04.00.02, where we have some HDMI fixes:

    processors.wiki.ti.com/.../TI81XX_PSP_04.04.00.02_Release_Notes

    Regards,
    Pavel
  • 0
    Prodigy 110 points
    Hi Pavel,

    One more thing i wanted to share is I am getting HDMI audio and video as expected even though the result on reading "SYS_STAT" register is "83".

    Regards,
    Bhasha.
  • 0 in reply to Bhasha Vyas
    TI__Guru**** 170625 points
    Bhasha,

    You can also explore if the below bits are as expected:

    INTR1[5] RSEN
    INT_UNMASK1[5] RSEN
    TMDS_CNTL2[0] RSEN

    Regards,
    Pavel