Hello.

Let me ask about TMDSFREQ[8:0],TMDSFREQ_FRAC[6:0] of ADV7619.

How does ADV7619 measure TMDS frequency?

Does it use XTAL?

I would like to know accuracy of the read back value.

With best regards.

Kikka

Hello.

Let me ask about TMDSFREQ[8:0],TMDSFREQ_FRAC[6:0] of ADV7619.

How does ADV7619 measure TMDS frequency?

Does it use XTAL?

I would like to know accuracy of the read back value.

With best regards.

Kikka

Hello, Jeyasudha.M-san.

Thank you for your reply.

Of course, I have already checked UG-237. But I am not sure how to measure TMDS frequency.

I would like to know the way how ADV7619 get the TMDS frequency value.

(For example, ADV7619 counts the width of TMDS clock x 128 by XTAL clock)

Best regards.

Kikka

Hi Kikka,

Looking at UG-237, Table 50. From the CHx_BL, CHx_LCF, CHx_LCVS and knowledge or XTAL you can define which standard the input is. Once you know the standard, by definition you know the TMDS frequency. For instance if I know the standard is 720p (regardless of 50 or 60 Hz) you know the TMDS clock = 74.25MHz.

In other words the TMDS clock is not directly related to the XTAL frequency but a derived value from values that are measured from the XTAL clock. Also CHx_BL is the only variable derived directly from counting XTAL clocks.

Hi Kikka,

Have you gone through the UG-237 Hardware User Guide? In this document there is an section talking about TMDS Measurement. I hope this would surely help you. Please check the below link.

http://ez.analog.com/docs/DOC-1881

Best Regards,

Jeyasudha.M