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Original question:

DS90UH929-Q1: External EEPROM

DS90UH929-Q1: External EEPROM

Nao
Genius 4905 points
Part Number: DS90UH929-Q1

Hi, E2E member

I would like to know the reading sequence of EDID in the External local EDID (EEPROM) mode.

My understanding is here.
1. Connect HDMI Source cable to HDMI port in DS90UH929-EVM.
2. Turn on the RX_5V from HDMI Source.
3. Turn on the External EEPROM on DDC line by RX_5V.
4. Pull-up to DDC line by RX_5V.
5. HPD pin goes to Hi from Low.
6. DS90UH929 acesses to Exteranl EEPROM and reads EDID data to internal SRAM in DS90UH929.
7. DS90UH929 provide the EDID to HDMI Source from internal SRAM.
8. HDMI Source provide the video signal of EDID.

Q1) Is this the correct procedure?
Q2) How long dose it take to Step8 from Step1?

Regards,
Nao




  • 0
    TI__Expert 4555 points
    Nao,

    Some corrections for you-
    2. 5V is transferred from within the HDMI cable.
    3. EEPROM Provided from 5V Supply of Cable
    4. DDC Should have a pullup R connected
    5. The HPD denotes when ca cable is inserted between sourch and sink devices
    6. 929 should be reading EDID from the EEPROM or internal SRAM
    7. This step in the sequence is not needed.
    8. HDMI Source provides the video signal.

    Assuming EDID info has 128 byte data and running at 100kHz I2C:

    100kHz = 10 us
    10us * 9 bits = 90us
    90 us * (4bytes(addr+ R/W command) + 128 Bytes) = 11.88ms.

    Regards,
    Jonathan
  • 0 in reply to Jonathan Nguyen
    Genius 4905 points

    Hi, Jonathan

    Thank you for your feedback but I have some question about it.

    I guess HDMI Source device need EDID data when they go to handshake.

    You say, step7 in the sequence is not needed.

    How does HDMI Source get EDID data in External EEPROM?

    Can HDMI Source get it directly from External EEPROM?

    Regards,

    Nao

  • 0 in reply to Nao
    TI__Expert 4555 points
    Nao,

    The HDMI Source can get the EDID data directly from either the external EEPROM or internal SRAM.

    Regards,
    Jonny
  • 0 in reply to Jonathan Nguyen
    Genius 4905 points

    Hi, Jonny

    Thank you for your quick feedback.

    Correct sequence it here right?

    1. Connect HDMI Source cable to HDMI port in DS90UH929-EVM.
    2. 5V is transferred from within the HDMI cable.
    3. EEPROM Provided from 5V Supply of Cable
    4. DDC Should have a pullup R connected
    5. The HPD denotes when ca cable is inserted between sourch and sink devices
    6. 929 should be reading EDID from the EEPROM or internal SRAM
    7. HDMI Source should be reading EDID from the EEPROM or internal SRAM
    8. HDMI Source provides the video signal.

    You say.
    Assuming EDID info has 128 byte data and running at 100kHz I2C:
    100kHz = 10 us
    10us * 9 bits = 90us
    90 us * (4bytes(addr+ R/W command) + 128 Bytes) = 11.88ms.

    Hence, 929 and HDMI Souce take 11.88ms to receive the EDID data.
    So, we need 11.88ms x 2 = 23.76ms to do Step6 and Step7.
    Is the time from Step 1 to Step 6 so short that it can be ignored?
    Is my understanding correct?

    Regards,
    Nao

  • 0 in reply to Nao
    TI__Expert 4555 points
    Nao,

    I don't believe you need to use the x2 multiplier for Step 6/7. Step 7 is not needed. Once the 929 reads the EDID from EEPROM or SRAM, the HDMI source should provide the video signal after that.

    Regards,
    Jonny
  • 0 in reply to Jonathan Nguyen
    Genius 4905 points

    Hi, Jonny

    Thank you for your quick feedback.
    Without Step7, how does the HDMI Source get the EDID data?

    Regards,
    Nao

  • 0 in reply to Nao
    TI__Expert 4555 points

    Nao,

    I'm sorry but I am a little bit confused about your question. The HDMI source is already plugged into the 929 port, so the source does not need to get the EDID data directly. The 929 should handle formatting the HDMI source based on what was read from the EDID data.

    Regards,

    Jonny

  • 0 in reply to Jonathan Nguyen
    Genius 4905 points

    Hi, Jonny

    Thanks for reply.

    Our customer's product is here.
    HDMI port ----- DS90UH929 ----- DS90UH940 ----- Display
    There is the EEPROM that has EDID data between HDMI port and DS90UH929.
    Users of this product can connect some camcorders or DVD players etc at HDMI port.
    I think some camcorders or DVD players(HDMI Source) need the EDID data in order to know the display resolution and data timing.

    Our customer wants to know the time to the HDMI Source provides the video signal from connect HDMI Source cable to HDMI port.

    Regards,
    Nao

  • 0 in reply to Nao
    TI__Expert 4555 points
    Nao,

    I apologize for the confusion. Yes the HDMI Source will take the info from the EDID and adjust the video signal accordingly to the EDID. The 929 doesn't do anything with the EDID other than allowing the HDMI source to access the content and then forwarding the video data to a corresponding deserializer.

    So to answer your question, the first calculation I mentioned should be your correct answer (11.88ms).

    Regards,
    Jonny
  • 0 in reply to Jonathan Nguyen
    Genius 4905 points

    Hi, Jonny

    Thank you for your quick feedback.

    Does following sequence correct?
    1. Connect HDMI Source cable to HDMI port in DS90UH929-EVM.
    2. 5V is transferred from within the HDMI cable.
    3. EEPROM Provided from 5V Supply of Cable
    4. DDC Should have a pullup R connected
    5. The HPD denotes when ca cable is inserted between sourch and sink devices
    6. 929 should be reading EDID from the EEPROM to internal SRAM
    7. HDMI Source should be reading EDID from the internal SRAM
    8. HDMI Source provides the video signal.

    Regards,
    Nao

  • 0 in reply to Nao
    Genius 4905 points

    Hi, Jonny

    I thought about the sequence again.

    Is it correct in the sequence below?

    NOTE: I changed Step 5 and Step 6.

    1. Connect HDMI Source cable to HDMI port in DS90UH929-EVM.

    2. 5V is transferred from within the HDMI cable.

    3. EEPROM Provided from 5V Supply of Cable

    4. DDC Should have a pullup R connected

    5. 929 should be reading EDID from the EEPROM to internal SRAM

    6. The HPD denotes when ca cable is inserted between sourch and sink devices

    7. HDMI Source should be reading EDID from the internal SRAM

    8. HDMI Source provides the video signal.

    Regards,

    Nao

  • 0 in reply to Nao
    TI__Expert 4555 points
    Nao,

    The 929 doesn't do any reading from EDID. It will only either provide the external EEPROM or internal SRAM for the EDID info to be placed. From there, the HDMI source should read from the EEPROM or SRAM of the 929 and then display the correct video data.

    Regards,
    Jonny
  • 0 in reply to Jonathan Nguyen
    Genius 4905 points
    Hi, Jonny

    It looks like we've crisscrossed our mail.
    Sorry for confused you.
    Please tell me correct sequence?

    Regards,
    Nao
  • 0 in reply to Nao
    TI__Expert 4555 points

    Nao,

    1. Connect HDMI Source cable to HDMI port in DS90UH929-EVM.

    2. 5V is transferred from within the HDMI cable.

    3. EEPROM Provided from 5V Supply of Cable

    4. DDC Should have a pullup R connected

    5. The HPD denotes when ca cable is inserted between sourch and sink devices

    6. HDMI Source should be reading EDID from the internal SRAM or External EEPROM of DS90UH929

    7. HDMI Source provides the video signal.

    Regards,

    Jonny

  • 0 in reply to Jonathan Nguyen
    Genius 4905 points
    Hi, Jonny

    Thank you for your feedback.

    Regards,
    Nao