SN65DP159: SN65DP159RGZR : unable to write TX_TERM_CTL 0x0B bit[4:3] register

sridhar medichelme

Part Number: SN65DP159

we using SN65DP159RGZR Retimer with following configurations:

    I2C_EN/PIN pin    = High (I2C mode)
    TX_TERM_CTL   = NC

Observations:

(i) The video output is blinking on and off (sync loss) for HD & 3G formats.
(ii) 1080p30 is getting detected as 1080i60.
(iii) Sync for 4K formats is not working at all.

However, when I read bit [4:3] in address 0x0B, they are always “00”.

We had updated the register 0x0B with following settings:

TX_TERM_CTL               : 11 – 75 Ω to 150 Ω,
TMDS_CLOCK_RATIO_STATUS   : 1 – TMDS clock is 1/40 of TMDS bit period,
DDC_TRAIN_SET          : 1 – DDC training disable

and then asserted APPLY_RXTX_CHANGE, register 0x0A[2] .

Even after this configuration, video is blinking on/off and Address 0x0B TX_TERM_CTL status is always “00”.

kindly help us in setting device in HDMI 2.0 mode.

over 3 years ago

0 David (ASIC) Liu over 3 years ago

TI__Guru**** 175781 points

Hi,

When you are in the I2C mode, are you actually writing to the TX_TERM_CTL? In the pin-strap mode, the TX_TERM_CTL bits reflects the value of the TX_TERM_CTL pin; writes ignored when I2C_EN/PIN = 0.

Thanks

David

0 sridhar medichelme over 3 years ago in reply to David (ASIC) Liu

Prodigy 20 points

Hi David,

As I mentioned in the question, We are using the device in I2C mode and we are writing the TX_TERM_CTL along with TMDS_CLOCK_RATIO_STATUS and DDC_TRAIN_SET followed by setting APPLY_RXTX_CHANGE.

We are seeing the write effect in TMDS_CLOCK_RATIO_STATUS and DDC_TRAIN_SET but not in TX_TERM_CTL.
TX_TERM_CTL is always "00".

Thanks,

Sridhar

0 David (ASIC) Liu over 3 years ago in reply to sridhar medichelme

TI__Guru**** 175781 points

Sridhar

Can you please share you schematic?

Are you pulling the I2C_EN high through a 65k resistor?

Thanks
David

0 sridhar medichelme over 3 years ago in reply to David (ASIC) Liu

Prodigy 20 points

Please find the attached schematic,

Yes, we are pulling I2C_EN pin high with 64K9 (almost equal to 65k).

0 David (ASIC) Liu over 3 years ago in reply to sridhar medichelme

TI__Guru**** 175781 points

Sridhar

I don't see an issue with your schematic. I would make sure R539 and R540 are not populated.

You have 10k pullup on SDA_CTL and SCL_CTL, have you tried different pullup resistor value such as 2k or 4.7k?

Are you seeing this issue on multiple DP159?

Thanks

David

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SN65DP159: SN65DP159RGZR : unable to write TX_TERM_CTL 0x0B bit[4:3] register