TMDS181: TMDS181 0Bh question

Yu Seven

Part Number: TMDS181

Dear Support

We want to use address 0Bh Bit 4:3
We find an issue.
When HDMI don't input, we can't write but can read it, When the input and output signal is ready, we can write and read.
It is a bug or application limit?
If we want to write it when HDMI don't have input, How can we do?

over 6 years ago

0 David (ASIC) Liu over 6 years ago

TI__Guru**** 177396 points

Seven

Are you using the EyeScan SW for the read/write? If so, then this is a SW limitation, not a bug.

Thanks
David

0 Yu Seven over 6 years ago in reply to David (ASIC) Liu

Intellectual 450 points

Hi David
I know it is a limitation, not a bug, but we need to use it,
When input and output is not ready
It's possible?

0 David (ASIC) Liu over 6 years ago in reply to Yu Seven

TI__Guru**** 177396 points

Seven

Please let me give me couple days and let me look into it.

Thanks
David

0 David (ASIC) Liu over 6 years ago in reply to David (ASIC) Liu

TI__Guru**** 177396 points

Seven

I was not able to find a register bit in the TMDS181 register that can cause TX_TERM_CTL bit to be set without the input being connected.

Thanks
David

0 David (ASIC) Liu over 6 years ago in reply to David (ASIC) Liu

TI__Guru**** 177396 points

Seven

One additional clarification, you are able to write to the register and change the TX_TERML_CTL bits. It is only when reading back, it will be read back as 0 if input is not connected. If input is connected, then you will able to read back the written value.

Thanks
David

0 Yu Seven over 6 years ago in reply to David (ASIC) Liu

Intellectual 450 points

David

Did you mean 0Ah Bit 2 write to 1 can be active?

APPLY_RXTX_CHANGES, Self-clearing write-only bit.
Writing a 1 to this bit will apply new TX_TERM, HDMI_TWPST1, EQ_EN,
EQ_ADA_EN, VSWING, Fixed EQ Value settings to the clock and data lanes. Writes
to the respective registers do not take immediate effect.
This bit does not need to be written if I
2C configuration occurs while HPD_SNK are
low, I
2CPD_EN = 1 or there is no HDMI clock applied and SIGN_EN is high.

0 David (ASIC) Liu over 6 years ago in reply to Yu Seven

TI__Guru**** 177396 points

Seven

No, I am still referring to register 0x0Bh Bit 4:3. The test I did in the lab shows I can write to these two bits without the cable connected. But in order to correctly read back the value of these two bits, I need to have the cable connected.

Thanks
David

0 Yu Seven over 6 years ago in reply to David (ASIC) Liu

Intellectual 450 points

Thanks David

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TMDS181: TMDS181 0Bh question