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YC Auto in ADV7802

Hi,

I'm currently trying to find an issue with a system we have developed that uses an ADV7802. The YC Auto mode fails with some s-video sources (different analog camera modules), where the s-video is detected as an composite instead. When we use a signal generator as source there is never any problems.

With a short cable between the input module where the ADV7802 sits and the camera module, is works reliably but when the cable length is increased with a couple of meters the ADV7802 starts to fail the detection of the s-video. With a signal generator we have no problem even with 60m cable.

I have checked the signal levels from the source with the automatic detection fails, and haven't found anything that could explain why the automatic detection of the C channels fails.

How does the YC Auto mode work? What is the different criteria that needs to be met for it to detect a source as an s-video or composite?

Any ideas what we should be looking for in the s-video signal that could cause the ADV7802 to fail the YC auto detection?

/BR Johan Karlsson

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  • And here comes the I2C read and writes we do during setup at startup and setup of NTSC video mode after detection of NTSC:

    ADV7802_IO_SLAVE_ADDR  0x21

    ADV7802_SDP_SLAVE_ADDR 0x41

    ADV7802_CP_SLAVE_ADDR  0x31

    ADV7802_VDP_SLAVE_ADDR 0x11

    # Init @ startup

    Slave address 0x21, Read address:  0x04, Data: 0x2C

    Slave address 0x21, Write address: 0x04, Data: 0x24

    Slave address 0x21, Write address: 0x0C, Data: 0x80

    Slave address 0x21, Write address: 0x0D, Data: 0xE1

    Slave address 0x21, Write address: 0x0E, Data: 0x04

    Slave address 0x21, Read address:  0x38, Data: 0x30

    Slave address 0x21, Write address: 0x38, Data: 0xB0

    Slave address 0x21, Read address:  0x10, Data: 0xB0

    Slave address 0x21, Write address: 0x10, Data: 0x90

    Slave address 0x21, Write address: 0x40, Data: 0xC2

    Slave address 0x21, Write address: 0x48, Data: 0x48

    Slave address 0x21, Write address: 0x47, Data: 0x48

    Slave address 0x31, Read address:  0x86, Data: 0x0B

    Slave address 0x31, Write address: 0x86, Data: 0x09

    Slave address 0x41, Write address: 0x00, Data: 0x7F

    Slave address 0x41, Write address: 0x12, Data: 0x00

    Slave address 0x41, Read address:  0x54, Data: 0x04

    # Setup of NTSC after detection

    Slave address 0x21, Write address: 0x0D, Data: 0x41

    Slave address 0x21, Write address: 0x0E, Data: 0x0E

    Slave address 0x21, Write address: 0x01, Data: 0x00

    Slave address 0x21, Write address: 0x02, Data: 0x01

    Slave address 0x21, Write address: 0x36, Data: 0x40

    Slave address 0x21, Write address: 0x00, Data: 0x0C

    Slave address 0x21, Read address:  0x38, Data: 0xB0

    Slave address 0x21, Write address: 0x38, Data: 0xB1

    /BR Johan

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  • And here comes the I2C read and writes we do during setup at startup and setup of NTSC video mode after detection of NTSC:

    ADV7802_IO_SLAVE_ADDR  0x21

    ADV7802_SDP_SLAVE_ADDR 0x41

    ADV7802_CP_SLAVE_ADDR  0x31

    ADV7802_VDP_SLAVE_ADDR 0x11

    # Init @ startup

    Slave address 0x21, Read address:  0x04, Data: 0x2C

    Slave address 0x21, Write address: 0x04, Data: 0x24

    Slave address 0x21, Write address: 0x0C, Data: 0x80

    Slave address 0x21, Write address: 0x0D, Data: 0xE1

    Slave address 0x21, Write address: 0x0E, Data: 0x04

    Slave address 0x21, Read address:  0x38, Data: 0x30

    Slave address 0x21, Write address: 0x38, Data: 0xB0

    Slave address 0x21, Read address:  0x10, Data: 0xB0

    Slave address 0x21, Write address: 0x10, Data: 0x90

    Slave address 0x21, Write address: 0x40, Data: 0xC2

    Slave address 0x21, Write address: 0x48, Data: 0x48

    Slave address 0x21, Write address: 0x47, Data: 0x48

    Slave address 0x31, Read address:  0x86, Data: 0x0B

    Slave address 0x31, Write address: 0x86, Data: 0x09

    Slave address 0x41, Write address: 0x00, Data: 0x7F

    Slave address 0x41, Write address: 0x12, Data: 0x00

    Slave address 0x41, Read address:  0x54, Data: 0x04

    # Setup of NTSC after detection

    Slave address 0x21, Write address: 0x0D, Data: 0x41

    Slave address 0x21, Write address: 0x0E, Data: 0x0E

    Slave address 0x21, Write address: 0x01, Data: 0x00

    Slave address 0x21, Write address: 0x02, Data: 0x01

    Slave address 0x21, Write address: 0x36, Data: 0x40

    Slave address 0x21, Write address: 0x00, Data: 0x0C

    Slave address 0x21, Read address:  0x38, Data: 0xB0

    Slave address 0x21, Write address: 0x38, Data: 0xB1

    /BR Johan

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