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ADV 7180 vertical sync issue

Question asked by RichW on Nov 12, 2015
Latest reply on Nov 21, 2015 by RichW

I could use some expert help!

 

We are using the ADV 7180 32 pin version. There are three NTSC output camera's connected via an external multiplexer to a single analog input pin. the digital output of the ADV chip feeds an IMX6 running an MPEG compression algorithm, and finally viewed on a standard LCD screen. When the external camera is changed, the system loses vertical lock ( H lock is preserved) and stable. the 'top of picture' scrolls slowly down the screen over a period of ~1 minute. Once vertical lock is achieved, the picture remains locked until the camera is switched once more and the process starts again. This does not happen every time and there are qualitative descriptions that "it seems to happen more often when the picture is brighter or darker " - which makes me think of an issue with input voltage levels changing and some related effect on loss of sync pulse.

 

-The front end uses a capacitve couple and a resistor divider and follows the application data sheet schematic.

-We note that while there is a horizontal sync pulse available on the horizontal sync pin, there is no vertical sync pin. Reading other FAQs, this seems to be a red flag and may indicate a biasing / drift / electrical issue or an incorrect register setting issue.

- We also note that disconnected analog pins are tied to ground using a capacitor , not a resistor and are therefore floating in a DC sense.

 

Here are the register settings -

 

/* Datasheet recommends */

const unsigned char sensor_init_data[] = {

  0x01, 0xc8,

  0x02, 0x04,

  0x03, 0x00,

  0x04, 0x4D,

  0x05, 0x00,

  0x06, 0x02,

  0x07, 0x7F,

  0x08, 0x80,

  0x0A, 0x00,

  0x0B, 0x00,

  0x0C, 0x36,

  0x0D, 0x7C,

  0x0E, 0x00,

  0x0F, 0x00,

  0x13, 0x00,

  0x14, 0x12,

  0x15, 0x00,

  0x16, 0x00,

  0x17, 0x01,

  0x18, 0x93,

  0xF1, 0x19,

  0x1A, 0x00,

  0x1B, 0x00,

  0x1C, 0x00,

  0x1D, 0x40,

  0x1E, 0x00,

  0x1F, 0x00,

  0x20, 0x00,

  0x21, 0x00,

  0x22, 0x00,

  0x23, 0xC0,

  0x24, 0x00,

  0x25, 0x00,

  0x26, 0x00,

  0x27, 0x58,

  0x28, 0x00,

  0x29, 0x00,

  0x2A, 0x00,

  0x2B, 0xE1,

  0x2C, 0xAE,

  0x2D, 0xF4,

  0x2E, 0x00,

  0x2F, 0xF0,

  0x30, 0x00,

  0x31, 0x12,

  0x32, 0x41,

  0x33, 0x84,

  0x34, 0x00,

  0x35, 0x02,

  0x36, 0x00,

  0x37, 0x01,

  0x38, 0x80,

  0x39, 0xC0,

  0x3A, 0x10,

  0x3B, 0x05,

  0x3C, 0x58,

  0x3D, 0xB2,

  0x3E, 0x64,

  0x3F, 0xE4,

  0x40, 0x90,

  0x41, 0x01,

  0x42, 0x7E,

  0x43, 0xA4,

  0x44, 0xFF,

  0x45, 0xB6,

  0x46, 0x12,

  0x48, 0x00,

  0x49, 0x00,

  0x4A, 0x00,

  0x4B, 0x00,

  0x4C, 0x00,

  0x4D, 0xEF,

  0x4E, 0x08,

  0x4F, 0x08,

  0x50, 0x08,

  0x51, 0x24,

  0x52, 0x0B,

  0x53, 0x4E,

  0x54, 0x80,

  0x55, 0x00,

  0x56, 0x10,

  0x57, 0x00,

  0x58, 0x00,

  0x59, 0x00,

  0x5A, 0x00,

  0x5B, 0x00,

  0x5C, 0x00,

  0x5D, 0x00,

  0x5E, 0x00,

  0x5F, 0x00,

  0x60, 0x00,

  0x61, 0x00,

  0x62, 0x20,

  0x63, 0x00,

  0x64, 0x00,

  0x65, 0x00,

  0x66, 0x00,

  0x67, 0x03,

  0x68, 0x01,

  0x69, 0x00,

  0x6A, 0x00,

  0x6B, 0xC0,

  0x6C, 0x00,

  0x6D, 0x00,

  0x6E, 0x00,

  0x6F, 0x00,

  0x70, 0x00,

  0x71, 0x00,

  0x72, 0x00,

  0x73, 0x10,

  0x74, 0x04,

  0x75, 0x01,

  0x76, 0x00,

  0x77, 0x3F,

  0x78, 0xFF,

  0x79, 0xFF,

  0x7A, 0xFF,

  0x7B, 0x1E,

  0x7C, 0xC0,

  0x7D, 0x00,

  0x7E, 0x00,

  0x7F, 0x00,

  0x80, 0x00,

  0x81, 0xC0,

  0x82, 0x04,

  0x83, 0x00,

  0x84, 0x0C,

  0x85, 0x02,

  0x86, 0x03,

  0x87, 0x63,

  0x88, 0x5A,

  0x89, 0x08,

  0x8A, 0x10,

  0x8B, 0x00,

  0x8C, 0x40,

  0x8D, 0x00,

  0x8E, 0x40,

  0x8F, 0x00,

  0x90, 0x00,

  0x91, 0x50,

  0x92, 0x00,

  0x93, 0x00,

  0x94, 0x00,

  0x95, 0x00,

  0x96, 0x00,

  0x97, 0xF0,

  0x98, 0x00,

  0x99, 0x00,

  0x9A, 0x00,

  0x9B, 0x00,

  0x9C, 0x00,

  0x9D, 0x00,

  0x9E, 0x00,

  0x9F, 0x00,

  0xA0, 0x00,

  0xA1, 0x00,

  0xA2, 0x00,

  0xA3, 0x00,

  0xA4, 0x00,

  0xA5, 0x00,

  0xA6, 0x00,

  0xA7, 0x00,

  0xA8, 0x00,

  0xA9, 0x00,

  0xAA, 0x00,

  0xAB, 0x00,

  0xAC, 0x00,

  0xAD, 0x00,

  0xAE, 0x60,

  0xAF, 0x00,

  0xB0, 0x00,

  0xB1, 0x60,

  0xB2, 0x1C,

  0xB3, 0x54,

  0xB4, 0x00,

  0xB5, 0x00,

  0xB6, 0x00,

  0xB7, 0x13,

  0xB8, 0x03,

  0xB9, 0x33,

  0xBF, 0x02,

  0xC0, 0x00,

  0xC1, 0x00,

  0xC2, 0x00,

  0xC3, 0x00,

  0xC4, 0x00,

  0xC5, 0x81,

  0xC6, 0x00,

  0xC7, 0x00,

  0xC8, 0x00,

  0xC9, 0x04,

  0xCC, 0x69,

  0xCD, 0x00,

  0xCE, 0x01,

  0xCF, 0xB4,

  0xD0, 0x00,

  0xD1, 0x10,

  0xD2, 0xFF,

  0xD3, 0xFF,

  0xD4, 0x7F,

  0xD5, 0x7F,

  0xD6, 0x3E,

  0xD7, 0x08,

  0xD8, 0x3C,

  0xD9, 0x08,

  0xDA, 0x3C,

  0xDB, 0x9B,

  0xDC, 0xAC,

  0xDD, 0x4C,

  0xDE, 0x00,

  0xDF, 0x00,

  0xE0, 0x14,

  0xE1, 0x80,

  0xE2, 0x80,

  0xE3, 0x80,

  0xE4, 0x80,

  0xE5, 0x25,

  0xE6, 0x44,

  0xE7, 0x63,

  0xE8, 0x65,

  0xE9, 0x14,

  0xEA, 0x63,

  0xEB, 0x55,

  0xEC, 0x55,

  0xEE, 0x00,

  0xEF, 0x4A,

  0xF0, 0x44,

  0xF1, 0x0C,

  0xF2, 0x32,

  0xF3, 0x00,

  0xF4, 0x3F,

  0xF5, 0xE0,

  0xF6, 0x69,

  0xF7, 0x10,

  0xF8, 0x00,

  0xF9, 0x03,

  0xFA, 0xFA,

  0xFB, 0xC0,

};

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